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The Solensia Cat Owner Feedback Page

Ron Hines DVM PhD

If your cat received a Solensia® injection(s) – or if you just want to share your thoughts on this new medication – please send your comments to me at yourpetsfriend@gmail.com and I will add them to this page. It is always nice to know your cat’s name and the region of the world where you and your cat(s) reside. RSH   Your comment in black, Owner updates in green My comments in purple   Scientist’s Comments in orange

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For Firey’s, February 21 positive update after his 5th Solensia injection, see his original 12/11/23 entry. Sadder ones for LaFonda Velveteen as well as Indi. 

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April 1, 2024

Hi, My 17 year old cat, Bear, had a Solensia injection last month. In the 1st week [thereafter] he seemed to be much more limber and took running jumps onto the bed. Before he would scramble up onto it. So I was delighted. Then a couple of days later he vomited every day for 4 days. 1 day 4 times! Then I noticed a rash and scabs around the whole underside of his neck, like a half circle. I washed and creamed it twice a day but it hasn’t gotten any better 3 weeks later. He still vomits occasionally too. He’s also started biting me which he’s never done before. Going by how the drug works, these symptoms make perfect sense because it prevents the nerve growth factor working. But NGF is needed for so many other biological needs. I’ve also read [on Facebook] some amazingly good reactions where it’s given the cat a new lease of life, but it seems to be pot luck. You’re playing Russian roulette. Needless to say Bear won’t be getting another shot.

J. H., London, England

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March 29, 2024

My cat [Frizzy] is a male 18+ years old and he has had 5 Solensia shots since October 2023. He is able to move better and gets up and down steps more easily, is more agile. The biggest side effect that I notice is scabbing under his chin on his neck and on his ear. The scabbing under his chin gets worse for 2 weeks after the injection and then starts to improve about 3+ weeks after the injection. I think I’m going to stop the Solensia for a bit, let’s see how he does but I’m almost positive that its causing the scabbing under his chin.

S.B., Spokane, Washington

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March 13, 2024

My cat, Sammy, is a spayed 17 year old who could not tolerate steroids anymore. She has had one injection [of Solensia] and is due for a second today. For the first three week post injection she was like a 10 year old cat. Racing up the stairs, wanting a lot of lap time, interactive. Her appetite dropped some and there was a definite withdrawal time for the steroids. She has had some vomiting and lack of appetite. This is a concern because she has never been a water drinker, no matter what I’ve tried (fountains, leaving out cups, flavoring the water, filtered, unfiltered, bone broth etc). I’m going to ask today if there is a way to mildly stimulate her appetite or treat for nausea. This approach is really the last chance for her and if it doesn’t work, she and I will just soften into the old age world and do the best we can for comfort. It has been incredible to see Sammy be herself again, without the steroids on board. No matter how this turns out, I’m grateful to have had a reminder of who she really is. I’m a bit frightened of outcomes, and this is really the best we can do for now, short of stopping and accepting the pain, which for her was debilitating. 

B. B., Helena, Montana

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March 10, 2024

My cat Lucky is 19 years old. Around 7 months ago he suddenly became lame in his hind legs. After an x-ray, our vet said it might be due to bone growths in the spine compressing the nerves. He suggested a CT followed by surgery, but that the symptoms might come back. We decided to not put our elderly cat through risky spinal surgery. We settled on prednisolone treatments which allowed him to walk again. However it was not meant to be a long term treatment due to [the drug’s] side effects. We tried unsuccessfully to wean him off of the prednisone. Gaba did not do much for him either. That was when Solensia was recommended. After one injection, we gradually lowered his prednisone dose to 0.1mL/day, and Lucky was still able to walk around, albeit a bit wobbly. This wasn’t possible at a prednisone dose of less than 0.7mL/day before Solensia, so we continued the injections. Lucky has had 4 injections to date. I have definitely noticed his balance becoming a bit worse this month. As well, I recently noticed a scab developing under his armpit. So I am quite worried Solensia is losing its effect in addition to side effects developing, but I hope he can continue to benefit from Solensia for a while longer.

C.U, Ontario, Canada

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March 10, 2024  

My sweet pusser, Callie, is 9-10 years old. Several months ago she stopped sleeping with us and would go upstairs & hide under my son’s bed. Her senior [lab test] panel came back normal. We already had a ramp at the end of our bed for our dog & Callie started using it versus jumping. She only responded to pain when her hips are manipulated. Our vet treated her overnight for dehydration intravenously. I started wet food & bought her a fountain for extra hydration. Callie is due for her fifth Solensia injection this month. I have mixed feelings about doing it again. I’ve recently noticed her back leg is now “gimp” when to my knowdege it wasn’t before. I can tell in her eyes [that] she’s spacey & she’s retreating/hiding. Sometimes, she looks at me like she has no idea who I am. She is eating her new wet ID stress food like a mad woman. Something tells me to stop the medication. My frustration also comes from the clinic being bought by a corporation/chain. The commutation is horrific. Hopefully, this cat Mama knows best.

J. M., Alabama

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March 6, 2024

We have 4 cats, 2 are senior kitties.  Sebastian is 20 and Belle is 17 years old.  We have tried Solensia with both of them for almost a year now. With Belle we could definitely see an improvement. She was moving more and seemed content which is great as she also has IBD, Feline cognitive dysfunction (CKD), hyperthyroidism and is blind. We adopted her at almost 13 [knowing] all these concerns. With Sebastian however, we stopped using [Solensia] on him. We didn’t notice many changes while he was on it. We had hoped to and we were afraid to stop it since maybe his benefits were so small and we had a hard time seeing them. About 2 months ago we started taking Sebastian to weekly acupuncture and laser therapy. We saw more changes after his appointments than we ever saw with Solensia. We are now hoping to also try Adequan with Sebastian in addition to his weekly acupuncture sessions.  His arthritis is in his vertebra/spine and he can’t take any pain medications due to taking prednisolone for IBD and the start of CKD (stage 1 our vet said).  Fingers crossed as Sebastian is a happy cat otherwise and loves people, eating and as much attention as he can get!

J. B., Duluth, Minnesota

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March 4, 2024

My korat cat, “Kitty” was 18 years old when he first started getting Solensia because he was limping on one front leg. My vet conclud[ed] he had arthritis and also that he had kidney disease. He has been taking Solensia now for 2 years. The 1^st injection worked wonderful, no limping anymore and more comfortable moving around. However he did start scratching his ears to the point that they were bleeding. My vet sent an email to the Zoetis, [they replied] ” This is the first time it happens they never heard [of] such a reaction”. The funniest [thing,] my previous vet, when I informed him about the scratching 2 years ago, contacted them and it was the same answer.… [So] I decided to get him Solensia every 2 months because a month and a half after Kittys injections, he would begin to limp again. He would be lethargic for 7–10 days after each injection. Also, he drank like he was parched after each injection. The vet said that was because of his kidney problem. [With time] he ended up being lethargic for longer than 10 days, moved less and howled at the sofa or toward the wall. Sometimes he does not [acknowledge] me. He is in his own world. I know he can see because I tried a few tests, but he doesn’t react to me calling him or being in front of him. I kept him on Solensia because it helps him moving around easily. [I do not want him] to be in pain. But the last times he got it, he had some kind of seizures and can barely walk. He does eat [his normal amount] but has lost 1.5 kg. He is due to have his injection this week but I really don’t want to have it done. I just sent an email to my vet asking if we could dilute Solensia with something and give him half of it. I would like to say to every cat owner who is happy with Solensia that I was extremely happy too at the beginning but I fear that it is at risk, seeing what happened to my cat.

C. W., French, but living in London, UK

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February 25, 2024

We have two 16 year old cats, Stella and Luna. Stella was having some shakiness in her back legs and not wanting to jump. [Our veterinarian suggested] Solensia. So Stella received several doses. We did notice some improvement in her mobility and abilities. The shakiness in her legs disappeared. At first we did not notice subtle behavioral problems that were beginning. One was loss of hearing. But then we started our second cat, Luna on Solensia. We did that even though we really had no concerns with arthritis in Luna. We were just hopeful that it would help a geriatric cat. After Luna’s first injection of Solensia, we started noticing that her left hind leg was started to give way, and she was having difficulty walking. After her second injection both of her legs became lame. She stopped jumping. She fell down every time she wanted to walk. It also affected her entire personality. She was drowsy and wanted to sleep. These are the same things that we were noticing in Stella. She too became an entirely different cat – not eager to participate in any activities. She just wanting to sleep alone. [they stopped the Solensia] Unfortunately Luna’s neurological function continues to be abnormal. But it has improved a bit. She has her good days and her bad days. Stella is now urinating and pooping all over the house. In addition, she is not answering when we call her name and doesn’t hear us when we open her bag of treats. Our two cats were on medication for hyperthyroidism prior to beginning Solensia injections. [In our opinion] Solensia is not a benign drug. It has significant adverse effects that are underrated and underreported.

B.K., Professor, Medical School, Davis, California

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February 25, 2024

Hello, My 14-year-old cat, Bebe started showing signs of arthritis. She was unable to jump very high, and her walk changed. You could tell she was in pain. We did a senior blood panel just to make sure she didn’t have anything else going on like diabetes or weakness her back legs. After [the tests] came back with everything normal, we started giving her Solensia. Bebe has been taking Solensia now for right at a year. She has had a tremendously good response. She chases her own tail like she’s a kitten again! However, she’s been 11 pounds her whole [adult] life. Last October and November she weighed 10.7 pounds. But by December, she only weighed 9.9 pounds. So at that point we decided to move her annual visit up and meet with our vet. They ran the senior bloodwork panel again and everything came back fine. They did a physical exam and couldn’t find anything that would cause the weight loss. We have seen that she’s drinking a lot more and she seems very hungry, but continues to lose weight. The vets entire opinion was to rerun the bloodwork but I’m wondering if it might be that it’s the Solensia that is causing her to lose weight. That could be just as unhealthy as the pain. Do you have any thoughts on how to progress? I know you can only give so many opinions, but I wonder if it’s worth bringing this up with the vet or if it’s just silly for me to think that.
Thanks,
D. B., Chapin, South Carolina

2-25-24 Dear Ms. B, There are so many illnesses that can cause cats to lose weight. The two most common ones in older cats are hyperthyroidism and failing kidneys. Both cause an increase in thirst. I assume that a T4 test was part of Bebe’s senior laboratory test panel. If Bebe were my cat, I would follow that up with a Thyroid panel (fT4 , T3 &  TSH test, perhaps a T3-suppression test as well). I would also repeat her BUN, creatine and urinalysis. However, it is common for the weight of older cats to begin to decline at ~ 11–12 years of age – even when your vet’s examination, laboratory and other test procedures can find nothing specifically wrong. At that same age, a cat’s ability to absorb fat and to digest protein begins to slowly decrease too. So if her kidneys or thyroid gland are not the underlying cause, a higher quality higher protein/fat diet might be helpful. The characteristics of her stool might give your veterinarians some clues as well. To read more about the many causes of weight loss in older cats, ask me for Williams 2015.pdf. I cannot tell you if Solensia has anything to do with her weight loss. One could discontinue it for a month or two and see. But those are all things you need to discuss with your local veterinarians. 

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February 19, 2024

Hello Dr. Hines, My cat Simba is a nearly 16 year old orange tabby. I’ve never had any concerns with his health – regular check ups and labs were always clean. I noticed he was peeing outside his litter occasionally and my vet chalked that up to osteoarthritis, then recommended Solensia. We started Solensia in Sept 22′. I didn’t notice any real change. In Dec 22′ he developed scabs on his neck and chest. I took him to the vet, she attributed it to allergies and gave me a steroid cream – all while continuing our monthly Solensia injections. The scratching was incessant and the scabs turned into open sores. I continued the steroid cream, cleaning with medicated pads, and oral antibiotics 2x a day, and continued the Solensia. This treatment plan was traumatic and made Simba hide 20 hours a day under a chair and there was never any improvement. Come April of 23′ I decided to look up Solensia and came to find that skin reactions were common. So immediately discontinued the injections. Gotta say I’m disappointed my vet wouldn’t have come to this months earlier. Anyway, once Solensia was cleared out of his system he was completely back to his normal self. However, now, February 24′ Simba had a dilated pupil in one eye so I took him in. After a thorough examination, a LARGE mass (essentially his entire body cavity) was found. I do not know the extent of the mass without him undergoing surgery which I’ve decided against. But I cannot help but think Solensia… I would never recommend this drug.

L., Vancouver, BC

2-19-24 Dear Ms. L., I was so sorry to read about Simba’s experience. No one can scientifically say that Solensia was involved. One of the most common tumors of elderly cats is lymphoma. Sometimes their superficial lymph nodes are enlarged. More often they are not. When an eye is involved, the most common cause is B-cell lymphoma. But I agree with your decision on conservative treatment. I would not suggest surgery, chemotherapy, radiation therapy or new age treatments if Simba was my cat or my patient. None are curative. None have been shown to increase longevity and all are very stressful to a cat and its owner. Some oral prednisolone might be palliative, but that would be for your local veterinarians and you to decide. RSH

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February 16, 2024

Hello, I started my 15 year old kitty on Solensia. He wasn’t limping but was slow going up and down our stairs, and he did struggle a bit to jump on the bed. I didn’t notice much difference [in that] after the shot. But shortly after his second shot he went into acute kidney failure. He has had mild kidney disease [several] years. [But] for the most part he was pretty healthy. I didn’t think there was a connection and neither did my vet. It could have just been a coincidence as he’s old and things like this do happen. We stopped the injection while we got him stable and on antibiotics to treat the infection. We started doing sub Q fluids every 2 days. He seemed to do fine for a couple of months, so we tried Solensia again. And once again, shortly after his second shot, he started straining and peeing blood. He had crashed again. I can’t say for certain that Solensia caused this, but it seems like it could have, and, if not, it’s very coincidental. Needless to say [he won’t be getting] any more [Solensia] injections. I don’t know if there’s much info on Solensia causing kidney failure, do I report this?

J.

As J. mentioned, there is no way to determine if Solensia played any part in her cat’s kidney issues. If her cat needed antibiotics and had blood in his urine, it is very unlikely that he was suffering from common feline age-related kidney decline. All his prior urinalysis results were said to have been normal as well. In any case, if it were my cat, I would let Zoetis know. R.S.H.

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February 13, 2024

We tried Solensia for our two cats. In one it was successful, in the other it was not. Jasper is 16. He has been getting Solensia shots for a year. He is very arthritic and has muscle wasting, but otherwise he is healthy. Solensia caused a huge improvement in his willingness to move around the house. He is now able to climb a few stairs to our bed and to enjoy the sunshine [from his] cat window bed.  He did develop a thin spot in the hair about 2 inches in front of his tail upon starting Solensia, but it has not gotten worse. Patrick our other cat was much younger, probably 9 or 10. He had multiple health issues. First he caught histoplasmosis which was not diagnosed for over a year until he developed sores on his joints. Patrick recovered from that, but then he caught toxoplasmosis. He also had kidney issues and a poor appetite. Patrick began limping, with no apparent source of pain. My vet suggested we try Solensia because it had relieved pain in Jasper. Patrick got one shot, and it did seem to cure the limping, but he also got very “spacey” and would stand still, staring into the distance, as if he forgot where he was or what he was doing. He also got itchy. He licked and scratched the skin around his neck bald. I don’t believe Patrick was arthritic. My layman’s conjecture is that if a cat does not have an overabundance of nerve growth factor due to arthritis, then Solensia may work differently on their nervous system. Over the next six weeks, Patrick gradually stopped eating and drinking and got very weak. I don’t blame that on Solensia because he had been doing poorly for over a year. Our vet gave Patrick a peaceful journey over the Bridge last summer.

A.H., Rural Central Valley, California 

3-11-24 Jasper is doing okay! The shots still seem to be effective and his weight is stable at just under 10 pounds. His February shot was 6 weeks after the January shot, and by week 5 he was noticeably moving less and not getting on the bed.  The muscles in his back legs are getting much smaller. He hobbles around taking very short steps, but he’s still up walking around 5 or 6 times a day. For now he’s hanging in, and we’re glad to have him. 

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February 13, 2024

My 13 old Siamese cat Alice developed arthritis over the last 2 years. It reduced her mobility and she couldn’t jump higher than 40 cm. I took her to the veterinarian [for] some laser therapy sessions and physiotherapy [because] I knew they had absolutely no side effects (thanks to laser I solved a problem I had with my knees). Alice’s blood tests were perfectly normal, but her X rays showed signs of arthritis. [So] we started to treat her with laser and physiotherapy. I also need to add that Alice has skin allergies [that have been] successfully treated with Apoquel for a couple of years with no side effects. After a couple of weeks on Solensia [which the vet suggested] she got better, but still had problems jumping. I was assured [Solensia] had absolutely no side effects and great results. The same day Alice had the first [Solensia] shot, I was surprised at the reaction. A few hours after the shot, the same day she had her laser and physiotherapy, she was playing and jumping as if she was a kitten. A few days later we stopped treating her with Apoquel because she didn’t scratch anymore. I was quite confused because one of the side effects reported for Solensia was scratching. After her 2^nd Solensia shot, she vomited and did not show any improvement. She just [acted the same as] before we started with the Solensia. Because I saw her scratching [again] I [put her back on] the Apoquel. A few days after her 3^rd shot I noticed she also had developed a rash near her ear and no improvements at all in her mobility, just stable. I found your webpage and realized there are no studies on the long term effects of Solensia and that the number of cats it has been tested on (only for 3 months) is really low and no information is provided about their age, health issues etc. [So] I decided to stop the Solensia and continue with the laser and physiotherapy [because] it worked and had no side effects. Thanks again,

M.C., Treviso, Italy

Dear M.C., I believe that you are correct in that there are no published studies on the long-term effects of frunevetmab (Solensia) on cats. Nerve growth factor, the biomolecule that Solensia reduces, obviously has beneficial effects in adult life, or God would not have created and maintained its presence through adulthood. Zoetis is an offshoot of Pfizer. In humans, tanezumab, Pfizer’s human equivalent of Solensia was refused approval in 2020 by the FDA and the EMA. That was because people receiving it needed knee or hip replacements sooner than those that did not receive it. But Pfizer still trying to obtain FDA and/or EMA approval by changing the suggested dose. (read here) And again, they are only looking at the effects of that drug over an 8 to 24-week period. During that time, one side effect was neuropathic itch.

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February 9, 2024

Hi Dr. Hines, I was glad to find your website and be able to read other’s experiences with Solensia. My cat Molly is around 14 years old. She has had about 13 Solensia injections since December 2022. She has hyperthyroidism (treated) and CKD (stable) and I believe has very bad arthritis. Prior to Solensia, she would only allow head pets and got very upset when we would try to [stroke] her back. However, she has been like that her whole life. Up to the past month, Solensia had been working really great for Molly. And she even started allowing us to pet her back, which led me to believe she didn’t previously like it due to pain and not just because she’s sassy. We noticed the difference almost immediately. She went from only sleeping on her floor bed to getting on our bed and back [on] the window [ledges?]. She could also jump on the bed without pulling herself up with her claws. (For the record, she does have stairs.) But a couple of weeks ago, I noticed Molly’s hind hocks were very swollen. I made an appointment with the vet and kept an eye on her. Later in the day I noticed she was now walking on part of her front ankle sometimes. After the vet visit on Feb. 4th, the doctor was stumped. She said that she thought it looked like either septic arthritis or immune mediated polyarthritis. She consulted another doctor and that doctor agreed. She said her front elbows were also very swollen. She goes back for X-rays this Sunday (Feb 11th). We decided to start her on antibiotics (Doxycycline) and see how she does. The doctor was concerned about starting steroids first in case it was septic arthritis and would make it worse. Molly is still eating, drinking, and using the litter box normally. Her behavior is also normal and has not changed. She does not seem to be in any more pain than normal, but she does take gabapentin twice a day as part of her arthritis treatment. Just yesterday she started frequently walking on her ankles instead of just occasionally. While we wait for our x-ray appointment, I took Molly to a different clinic for a second opinion yesterday. These doctors were also stumped. They recommended proceeding with the x-ray and if they couldn’t come to any further conclusions after that, to do a joint tap and have the fluid tested. I cannot say for sure and obviously, I don’t have any solid proof, but my suspicion is that Molly’s body is reacting in some way to the Solensia. That isn’t to say that it is a bad drug. I haven’t come across any other cases like Molly’s. We are discontinuing using Solensia on her. Her next injection would be Feb. 20th. So, we have about 11 days to go before it should wear off. I’m hoping we will see improvement after the Solensia wears off as we have not yet seen any improvement from antibiotics yet. Hopefully, I can report back to you with some news of improvement in a few weeks. Best, 

R. M., Portland, OR

2-11-2024 Experimentally, gabapentin (Neurontin) which Molly is also receiving can cause dose dependent leg puffiness and weakness. R.S.H. (read here)

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February 8, 2024

Dear Dr. Hines, Our two 17-year-old boys, Pingu and Pumpkin, are both showing signs of arthritis. In Pingu the symptoms are still fairly mild. He is active and playful for a cat his age, but you can see that his front paw bothers him when he jumps down from a high surface or sprints too fast. We tried him on Solensia for 3 months, and saw no improvement in his symptoms, but no negative side effects either. [So] we discontinued the Solensia because it wasn’t helping him.

Pumpkin’s symptoms were more severe: He was moving very little, his back legs were stiff when he did move, and they trembled when he was laying still. He didn’t want to sit in my lap anymore, but would sit next to us to be petted. Pumpkin did very well on Solensia for the first 6 months: He was much more active, flexible, jumping up on things again, grooming himself more, the tremors were gone, he was back on my lap, and has miraculously decided after knowing him for 13 years that my partner’s lap is now also acceptable 🙂 He’s on his 7th shot now, and has, unfortunately developed a scab by his ear which he keeps scratching open, and his belly is showing bald patches where he is over-grooming. At the same time though, we discovered fleas on both cats: I have no idea where they came from as they barely go outside and it’s winter here. We treated them for the fleas yesterday, and I very much hope they were the cause of Pumpkin’s itchiness and baldness because Solensia has otherwise been fantastic for him. I will update to let you know whether the flea treatment has solved the problem.

C. C., The Netherlands

Please do.

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February 2, 2024

[Solensia] has been a godsend for my 16 year old, Maine Coon cat, Indi, She could only take about 3 steps before Solensia and her legs would fall out from under her and she’d have to sit for a while before she could take another few steps. After Solensia, within 2 or 3 days of the first injection she was walking from room to room. I [had] already purchased stairs for her. She used to go up 2 steps and stop and then 2 more steps. Now she’s just walking up them. She’s not flying around the house like a kitten. But I cannot believe the difference and no side effects I’m aware of – none like I’ve been reading. I think the side effects I’ve read about are minimal and not usually life threatening. So I think it’s worth a try. If there is an allergic reaction, then don’t do it again. But I’m shocked at how good this stuff is so far. I know Some pet parents who say their cat died shortly after the injection. We have to keep him mind that these are old cats and it doesn’t necessarily mean [that they died from Solensia]. Old cats [could always be] on their way out at any time. [Anything] that makes them feel better is worth it. Indi would just sit. Now she’s lying on her side and relaxed. I’m so happy.  She has oral cancer and she’s end-of-life. But she’s still walking around, she’s still eating and she’s still purring. And she’s still cuddling so it’s all good for me.

D. W., Friendship, Wisconsin

2-4-2024: She [had] been in good spirits and eating well swallowing whole kibble and treats and licking wet food and mousse a lot and drinking water.  But just today cant eat because her jaw is so swollen and the cancer is growing into her mouth under her tongue and inhibiting her ability to use her tongue.  Shes hungry and Im devastated.  I started feeding her by hand and with a dropper and will give her fluids to keep her happy and feeling ok until she decides to stop eating. At least she can still get around. The timing sucks. 3-2-2024: Indi crossed over the Rainbow Bridge this past Wednesday. I am devastated. I read a lot of the reviews about Solensia and it sounds like certain cats are allergic to it and there is no way yet to identify which cats might have a reaction. I am grateful for Solensia. It definitely helped her get the most out of her last few months D. W.

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January 30, 2024

Hi Dr. Hines! Our 17 year old girl, LaFonda Velveteen, is in good health outside of some dental issues. She will be 18 this summer. She got her first shot of Solensia on 30 December, 2023, for what the vet believed was OA. She was limping on one front paw, and when the vet palpated the paw, we could hear crackling noises. At the same visit, she was given an injection of dexamethasone as well. I saw an almost immediate improvement in her mobility. But about a week later, her appetite decreased a lot, and she became lethargic, often crying at the ceiling, or vocalizing in weird spots, for no apparent reason. By mid January, she developed a very hard, asymmetrical mass behind her right ear, going up onto the top of her skull. It is roughly the size of a US quarter coin, and perhaps 1/4 inch thick. It rose quickly but has grown no bigger. Took her back to the vet on January 19th and everyone was puzzled by what the mass could be, as it was hard as a rock and could not be moved around, at all. She flinched and tried to bite me, when I first found it, but by the time the vet saw her, she had stopped acting as if it hurt when we touched the mass. That day, we found that she had also lost a whole pound of weight, since the end of December. She was given a shot of triamcinolone and sent home with some mirtazapine ointment to put in her ears, to help her appetite. She has started to look and act confused, lying in the same spot for hours and hours, and her pupils are always dilated. She looks absolutely miserable and does not want to be groomed, especially around her tail end, which she used to enjoy. She has no trouble finding the litterbox or the water bowls or her fave spot on the bed. She has stairs to get on and off the bed, so she does not have to climb. She no longer jumps up or down, at all. I plan on holding off on the 2nd Solensia shot, until we can be certain that these oddities are not side effects of it. I would like to think these symptoms will wear off, eventually, though I’m not sure how long the Solensia stays in a cat’s system. I am hoping that they do wear off, as it is distressing to see her looking so miserable and lost.

K. C., Terrell, Texas

2-22-2024 Hi Dr. Hines, I’m following up with you on our cat, LaFonda Velveteen. Unfortunately, the lump on the back of her head continued to grow in spite of all the treatments they tried, and then spread to her upper lip, resulting in a bleeding mass that the vet thought was cancer. She stopped eating and drinking, entirely and was unable to even sit up on her own. So we chose to humanely euthanize her. I will never know whether the issues arose from the Solensia, or just organically, but at least she is no longer suffering. Thank you for your hopes. I wish I could have reported better news. Yours, K.C.

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January 29, 2024

Hi, my 16 yr old diabetic cat, Scooter received his first Solensia injection 1 week ago along with a Convenia shot for a possible upper respiratory infection. He had had Convenia shots before with no side effects. All seemed to be going well until [the] 6th day [when] my cat stopped eating and started vomiting. On day 7, he was still not eating, vomiting seemed to stop, but last night had an explosive diarrhea. Today, he is still not eating. [I am] taking him to the vet this morning. Seems like he had a bad reaction to it. I will not give [it] again. I will give you an update after the vet appt.

P.B., Boulder, Colorado

January 15, 2024

The email about R.Y.’s cat Tonka seems to mirror events since my 13 year old short hair cat, Lilly, began her treatment with Solensia. Lilly had her first Solensia injection towards the end of November 2023. All seemed fine, she was soon scampering around like her old self. She had her second injection 4 weeks later and within a week Lilly was scratching, twitching her ears constantly and over grooming. She developed sore spots just inside her ears, a scab under her chin and developed ‘cat acne’ on her chin. My problem is that I also began introducing a new variety of gastrointestinal food to Lilly in the middle of November (before she had her first Solensia injection). So Lilly has been eating her original gastrointestinal food with about a third of it replaced with the new variety. I stopped the new food immediately on noticing the scratching symptoms but now don’t know whether the cause is Solensia or a food allergy. Lilly is due her next injection in a few days, I’m wondering whether to postpone this.

C.D., ****ordc@gmail.com, United Kingdom    

1-15-24 It is always difficult or impossible to identify which change causes a problem when two or more changes are made simultaneously. The only way to do so is to discontinue the changes one by one, wait about two weeks, and see if the problem resolves or at least improves significantly. I do not know the severity of Tonka’s gastrointestinal symptoms or their underlying cause(s). Ask your veterinarian what he/she thinks about that. If she were my cat, I would put off administering further Solensia injections. Arthritis is debilitating, but it is not life-threatening. Whereas bad reactions to drugs can be. The next email is one I received from a very astute research scientist friend of mine who is also a veterinarian. Much of it will probably be incomprehensible to you (it was to me). So the links to Wikipedia and relevant NCBI research articles furnished by Dr. Pan were my additions:

Jan 6, 2024 Dr. Hines, Your opinion about histidine [a precursor of histamine] is absolutely a potential mechanism [of pruritus/itch]. I did some literature searching, and it looks like monoclonal antibody – associated pruritus is not uncommon. Many are observed in cancer therapy [drugs]. (1) (2) (3) (4) (5) (6)  I don’t think there is a settled mechanism of pathogenesis, and it is likely multifactorial. The most common mechanism is the aberrant binding [not normal or expected] of antibody to non-target cells, such the PD-1 on T-reg and EGFR on keratinocytes and hair follicles, and results in unwanted apoptosis of these cells. Similarly, since frunevetmab [= Solensia] is a nerve growth factor antibody and nerve growth factor is richly produced by keratinocytes in the skin, it is highly possible [that it might] result in an immune response against [those] skin cells and cause pruritus. (7) I hope this makes sense.

Richard (Yi) Pan, Columbia, Missouri, USA

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January 8, 2024

Hello Ron, My 15 year old cat, Kit, suffered from hyperthyroidism [for which he took methimazole] but was quite well with a slight discomfort from arthritis. I would take him for a walk through the park every day which he loved just to keep everything moving and keep him happy. On 4th December 2023, he had an appointment to renew his thyroid medication and have his [periodic T-4] blood test. His blood [results] were fantastic and we thought we would have him for a few more years. Unfortunately the vet suggested Solensia would make his arthritis more comfortable for him since it had worked well for her other clients. So we agreed to one injection to see how he got along. They took him to the back, shaved his neck for the bloods and gave him the Solensia injection. As soon as we got home, his voice changed to a moaning and he started being lethargic and not interested in [his] usual things. A week later, a noticeable lumps had grown around his neck and shoulders, which by day 11 were preventing him from eating and drinking altogether. The vet put him on antibiotics in case it was an infection. By 15th December 2023, he could not move, eat or drink and was growling in pain to touch. Sadly on this day I had to have him put to sleep because the pain he was experiencing was devastating. So less than 2 weeks after 1 Solensia injection he is dead. I have since spoken to other friends whose cats had hyperthyroidism and were given Solensia and were dead from a stroke within the week. Perhaps Solensia doesn’t agree with hyperthyroid medications and hasn’t been tested for this [possibility] previously. 

Warm regards, J.T. on the Gold Coast of Australia

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December 31, 2023

Hello dear, My cat Brucie is 21 years old, FIV positive and has hyperthyroidism (under control). The vet always comes to treat him at home as he would be too stressed at the clinic. A month ago my vet said he has something very good for his arthritis.That it would be without risk and would do him so much good. So Solensia was given. Initially, after 48 hours, he was more energetic, jumped on the window sill. I was over the moon. However, he started to change, no more sleeping in front of the radiators, he hid in the back of the wardrobe, started hissing all alone and at his food bowls, drank way too much water, did not react to his name. He scratched nonstop and tried to bite himself (he no longer has any teeth). Then it got worse, he hissed then fell over and remained on the floor his left hind leg unable to move for like a minute at a time then continued on to hide. This happened about 5 or 6 times. That was the worst reaction, I did think he had a stroke because his ears also twitched a lot. The veterinarian came and stated his reactions are very slow, pupils too wide, he has a slight arrhythmia and prescribed antiepileptic medicine (which I have not given him yet after reading the Solensia feedback). He said it has nothing to do with Solensia but as the 1 month injection was due, and I was hesitant, said that he cannot take any responsibility. So I said no to the 2nd injection. This was last week and he only hissed 2 more times after that but did not fall over anymore. He jumps on the bed and sleeps a lot more now. It seems the effects are wearing off but I am still really scared. The vet said what we read on the Internet is not scientific and cannot be trusted, if a bus had hit him it would have been blamed on the Solensia also (!). I would not recommend to anyone injecting Solensia, based on my experience. 

H.A., Brussels, Belgium

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December 27, 2023

Our 14 yr old cat, Alice, was [given] Solensia on June 15, 2023. She had reactions starting day one. She was lethargic and did not eat or drink or move for three days. She growled when we touched her [ ]. We had never experienced anything like this with her before. Several weeks after the injection she was still limping but was mostly back to normal. She itched and pulled out hair excessively but the most troublesome new development were her teeth and gums. She had to have two teeth pulled as a result of gingivitis less than a month after the injection. [Near] the end of September Alice developed a fast growing lump near her hip. After antibiotics and steroids did not help and an x-ray verified no broken bones, a fine needle aspiration was done and sent to pathology. The week of Thanksgiving it was confirmed to be a malignant injection site sarcoma on the side she was administered the Solensia. It has now been two weeks since the mass was removed and [the tumor] has already begun growing back. Gulf Coast Oncology is fully booked and our appointment isn’t until February. I have so much guilt. The injection was sold as a beautiful thing to help our senior cat with her osteoarthritis pain. Don’t give your cat any new medications until you do your research. 

T. M., Lake Jackson, Texas

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December 24, 2023

My cat, Cleo is 16 years old and had a normal blood [test] panel last year. She was offered to try Solensia about 3 months ago during her annual check when upon questioning from her vet it sounded like she had OA pain (less movement, less grooming, limping). After the first 2 shots we saw noticeable improvements in her mobility and the frequency of grooming. Then after the 3rd shot a month ago, we noticed increased lethargy. Then a week ago she lost her appetite. She also started doing some middle of the night yowling and kicking out glass patio door (so maybe some signs of dementia?). I took her in and the vet said she had a fever and gave her fluids and checked her labs. The labs returned and she has decreased red cells and platelets, a non-regenerative anemia. Negative testing for infections or FeLV so possibly bone marrow cancer or immune mediated anemia. She has had 4 days of oral steroids now and seems to be improving a bit but waxing and waning. I’m not sure how much of this is coincidental but I fear that the solensia may have had something to do with it. So if she recovers from her current status I won’t be continuing solensia. 

J. O., San Jose, California

12-28-2023 Hi Dr Hines, Just wanted to give you an update that we put Cleo down 2 days ago. She was just getting very lethargic and her back legs started to stumble, She may have been light headed with the anemia she had. She also stopped eating in the mornings which is unusual for her. I dont know if it was Solensia related or just a coincidence but just thought Id give you an update. Thanks I am so sorry to read that about Cleo. But thank you for letting me know. As you mentioned, these are all old cats, and, like old people, they tend to have multiple chronic health issues, and it can be impossible or nearly so, to know how medications do or don’t interact with these issues. Best wishes, Ron                                      

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December 22, 2023

Hi there

My almost 16 year old cat, Bella, was given one shot of Solensia for arthritis. She is half abyssinian and half moggy [mixed shorthair]. Within two weeks she was itching her head.  Four days later she had lesions across both side of her forehead and right around and under both ears.  At its worst she had almost no skin left on her forehead and cheeks, but yet continued to scratch, even though it must have been so painful.  She was treated with steroids and antibiotics but to be honest nothing solved it until the Solensia got out of her system and we are only just coming out of it now.   For four weeks she had a collar on to stop her itching and we had to keep her sedated every day on Gabapentin to try to help.  I wish I had done my research prior to the treatment.  The only side effect I was advised of was potentially itchiness on her back.  It was horrific and not something I will ever allow in any of my animals again.

Thank you for raising awareness of this. Kind regards

D. B., Auckland, New Zealand

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December 11, 2023

My cat, Firey, is an older (15?) neutered male. We took him to the vet 2 months ago because he had signs of arthritis. Pulling himself up onto chairs and beds, but also searching for safe places. We think [perhaps] to curl up and die without being attacked. The vet confirmed arthritis in one hip and offered the option of daily inexpensive tablets (I don’t remember what) with frequently bad side effects or Solensia, a monthly injection, which is what we chose. Firey’s response has so far been VERY positive, but having read some of the emails published here, we will be watching closely for adverse changes. After the injections, Firey resumes his daily patrols of our rural location. He carefully gets up on beds and chairs, but without reluctance. He just looks for the easiest route. This tapers off over the 4 weeks. Apparently there are 2 units in a package – Firey is getting only one unit. I started looking for information because he has started having very satisfying sexual relations with stuffed toys! A completely new behaviour. We took Firey to the vet 2 months ago prepared for that to be “the end”. We look at the 2 months since as a bonus, 2 months where he has been on top of the world. If you could see him after he “has his way” with the stuffed toys – he’s a very happy boy!

R. T., Younghusband, South Australia

12-12-23 This toy romance report might not be as far-fetched as you might first suppose. (read here & here) RSH

1-22-2024, An update on Firey. Firey just had his 4th single unit injection of Solensia. During the 3rd month, no adverse developments have been observed. He continues to freely patrol our rural location.The new (since Solensia) sexual behaviour with stuffed toys continues unabated. Fingers crossed. R. T., Younghusband, South Australia

February 21, 2024, Firey has had his 5th single unit Solensia injection. The 2nd, 3rd and 4th injections were administered by vet nurses. This time we got a vet to conduct a checkup before the injection, looking for adverse symptoms. None were found, so the injection was administered. During the 4th month, Firey has been moving freely. He has not been patrolling as much, but the weather has been hot and like us, he has been spending more time inside.His sexual interests continue.

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November 8, 2023

Dear Mr Ronald,

My cat Pinky B: is 19.5 YO. For the past 5 years he has been treated with Convenia every few weeks for a polyp in his middle ear (the only treatment which still seems to help). For the past 2 years he has started to develop dementia (with ups and downs of disorienting, yowling, sundowning, general distress and confusion). He also suffers from osteoarthritis for the past 5 years. He was treated with gabapentin for 1.5 years. It helped but had harsh side effects especially lethargy. So we stopped. This year he’s on Neurogen pet ultra (we’re in Italy), CBD occasionally and lion’s mane, all 3 seem to have good affects. But he is still deteriorating with pain and cognitively. His first shot of Solensia was on November 2nd. His reaction felt almost magical ️ we were so thrilled.. 2nd shot was this Tuesday. Since then his cognition has gotten worse than before the 1st shot. Yowling, lethargic, stiff mobility, lack of balance, overall seems very gloomy. I do see a slight improvement this morning and am filled with hope that he will overcome this. Obviously am very unsure as to whether I should give Solensia another try. This seems too dangerous, especially having read testimonials on the page.

G. S., Bologna, Italy
December 25, 2022  Last Friday we had to help my baby Pinky to cross over. He had his ups and downs mentally and physically, but the direction was an obvious downhill. At our vet’s suggestion we tried cortisone for the pain, for two weeks but it didn’t seem to do much. Even prior to the 1st Solensia shot, he was at a disadvantage [being] a near 20 year old kitten with dementia episodes and noticeable osteoarthritis and sometimes needing to help him stand when in the toilet. Two nights before the decision, I started accepting it was time. My Pinky, my love of 20 years – half my lifetime.. I’m so broken.

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December 6, 2023

My cat Coco is a 17 year old male Himalayan. He started Solensia in the summer of 2023. At first, it was great. He seemed more mobile and I noticed him going up and down stairs easily. After the 3rd dose though, he developed intense itchiness and subsequently scabs all over his neck and head and side of his body. The sheer movement of his back legs needed to scratch himself surely did not help his arthritic hips. He lost a lot of hair. Also, he was insatiably hungry and vocal. (I know opposite of other cats who lost appetite). I decided to stop the Solensia. It was good but the side effects made me have to stop. He is a CKD stage 2 cat so Metacam is out. I now am relying on gabapentin, buprenorphine, and CBD for his pain. I am looking to start glucosamine/chondroitin or another supplement after I do some research. I was pissed I had to take my cat to the vet for Solensia shots (he is so stressed going to the vet). I am more than capable of doing a sub q shot. Anyways, I tried to research some side effects of Solensia and there was limited data. Seems like a great treatment, but not for all cats. His itching and scabs stopped after Solensia was ceased. Coco’s appetite was insatiable on Solensia. His appetite is normal now too.

L. R., Vancouver, Canada

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December 2, 2023

My 17 year old boy, Pancake (turning 18 in April) was recommended Solensia for his arthritis around July of 2023. At first he responded great and was moving around more. After the 2nd or 3rd time taking him I noticed he was losing weight at every appointment (about .2 – .5 pound a month) and at home he was acting like he was starving. I asked them every time about his weight and if that was a problem. I was told he is overweight anyway and is probably just loosing pounds due to the extra walking. I decided to make a senior exam appointment and do a full panel because that just didn’t seem right to me. It came to our attention after doing his blood work that he has early stage 2 ckd (chronic kidney disease) I did not see any decline in his health or weight until starting the Solensia shot. I am now doing research about it and find that there isn’t much research on this drug especially in cats with ckd. My vet then told me to continue the shot since it is helping him move around. After reading all these posts and deep diving into the data and studies on this drug I do not think I will be continuing with this route. 

K. H., Grand Rapids, MI 

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November 27, 2023

My 14 y/o cat Helios was recommended Solensia for the calcium bridging he has in his back [ankylosis]. He is otherwise in good heath aside from a few teeth that need attention and a slight heart murmur which makes him not the ideal candidate for the sedation needed to sort out the teeth. After the first Solensia shot on October 7th, he seemed sleepy for a while. But then he was running around like a kitten so I thought it was fine and helping him. He had his 2nd shot on November 10th. He seemed fine at first but then I started noticing scabs on his face and chin. 2 weeks after the shot he started limping on his left front leg. Yesterday I noticed he has a big lump on his front leg by his chest and this morning I found his left front leg very swollen! It’s twice the size of his other leg! I am stopping these injections immediately! My vet who is usually awesome didn’t mention any of these side effects when Solensia was recommended to me. I feel awful that it has hurt my little buddy. Helios is now very lethargic and I am concerned about what else this has done to him. 

Lisa From BC Canada

11-28-23   I took Helios to my vet yesterday for a re assessment. He feels that the lump and swelling of his leg is somehow related to the Solensia because it showed up so soon after the 2nd shot with no prior indications of any problems and normal bloodwork. He gave him a steroid shot that lasts 2 days to help with the swelling. He thinks that the Solensia should be out of his system in the next 2 weeks. Helios lets us touch the swollen area and the lump without any sort of [pain] reaction. My vet now recommends we use CBD to help Helios with his discomfort and mobility issues. Vet said he will check in with me in 2 days to see how things went with the steroid shot. If things have not changed by the time the Solensia is out of his system we will do x-rays and blood work to find out what is going on. L.A.

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November 18, 2023

Rosa, our 15 year old cat started Solensia in July 2023. The first injection had her scaling the fence, and tightrope walking along the top. Rosa seemed so much happier to be more mobile. But this October after her last injection she didn’t seem to pick up so quickly as the previous months and started turning away from her food. Numerous trips to the vets revealed everything seemed to be fine. The vet gave her medication – mirtazapine to help stimulate her appetite. At that time the vet did not link this weight loss to the Solensia. Rosa started eating again, just small amounts. We knew she was due for another Solensia injection last Tuesday, so this was booked in, and the vet wanted to check her weight as she had lost some over the period she had not been eating. Rosa arrived home that day with a bounce in her step and clawing the scratching pole quite happily. She had been separating herself from her sister over the final weeks – which was very unusual. The following morning, she didn’t get up…but did eventually to use the dirt box. She then went to lie in the sun another usual routine. While I was doing my art, I found her then tucked into a corner, and somewhere in that time she lost control of her bladder twice…struggled to get to the dirt box to pass a poo. I was amazed her whole movement had changed she could hardly walk or stand. We rushed her to the vet, who said, this change maybe neurological. The vet who had seen her the previous day came in and said – goodness she’s gone downhill since yesterday. At that time, we thought the only solution to help her was to let her go to be at peace. Since Rosa’s passing (Wednesday 15^th November) my gut told me something was not right. Why did this happen so quickly? I started to search Solensia and found other people had experienced similar things with their cat using this product. I acknowledge others have had no issues. If we had held onto her a bit longer, would Rosa have got through this? Looking back, it seems to fit with other experiences, and given the chance, seeing the signs and had we had more information we would have stopped the medication earlier on. For anyone else considering this medication I would say please do your research first so you can make your choice. We miss Rosa so much – Daisy her sister is so lonely.

C. G., New Zealand.

11-19-23 Dear Ms. G,  Thank you for letting me and others know about Rosa’s experiences with Solensia. I am so sorry to read about her passing. Solensia is a venture into poorly understood science. Veterinarians and physicians just do not know yet what the side effects of inhibiting nerve growth factor the way this drug does might be. God did not produce NGF without important reasons for doing so. That is why similar drugs have not yet been approved for human use by the FDA or the EMA. 

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November 5, 2023

My 18 year old female kitty Porkchop has osteoarthritis in her hips and shoulders. One night before I knew how severe it was, she was laying on me and fell to one side cuz her shoulder couldn’t hold her. Then she kinda fell off the bed and started to walk and I noticed her opposite hip/leg wouldn’t work. She laid there for 20 mins before she could get up. The vet did a neurological exam and she was perfectly normal. Then they did an exam on her limbs and she growled in pain with the same limbs I saw not working for her. They suggested Solensia. I never wanted to see that happen to her again so I said yes. After the second shot she was back to her old self. Playing harder, Running faster, jumping and being her crazy self. Now, after maybe 8 shots, it seems to not work anymore. Her hips are unstable again and her right back leg has a limp now. I was so hopeful and now I’m so discouraged. 

E. L., Grand Rapids, Michigan

11-25-23 Hello, sorry for not getting back sooner. Yeah so after two shots I saw the full effects. Porkchop was back to her old self and had stability in her hips again and played, ran, jumped like normal. Now 8-9 months later she’s limping and her back right leg is weaker. They did what they can do in regards to a feline neurological exam back then and she was normal. I was concerned about [perhaps] a stroke but I guess she did not have one according to them. When they did their exam on her limbs and felt her body they could definitely feel the muscle mass loss and arthritis due to her age. When they stretched her limbs she growled when it came to the arm and leg that had stopped working briefly. They were stiff and painful but after the shot they became more loose and she didn’t growl. It just sucks watching your animal grow old. E.L.

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October 25, 2023

My cat Butterscotch has terrible arthritis. He is 20 years old and is otherwise in generally good shape with very mild kidney decline. My vet recommended Solensia so we tried it. After the first shot, he started to move around much better and I thought it was a miracle. After the second shot, he was slightly better but not the same level of improvement. On the third month, Butterscotch got his third shot. Since that shot, he is confused and lethargic.  It seems like he has dementia. His limping is now much worse. I am not sure what is happening. He had a physical right before the first shot and was okay. His food has not changed. I have decided to stop his shots and see what happens. As with most clinical trials not every adverse reaction is observed. But something is definitely not right.

S.L., Livonia, Michigan

You are right. There seem to be extreme differences in on how Solensia affects cats. As I mentioned to previous cat owners, the most important thing I would like to learn is, are these negative effects – when they occur – permanent or temporary and what would be the best way to treat or prevent them. Solensia reduces your cat’s level of NGF. Less NGF in the body reduces pain. Perhaps where it’s given, how frequently it’s given and what other meds are given are more important than we thought. One needs a certain amount of NGF to retain one’s mental abilities and nervous system. (read here) Perhaps the suggested dose is just too large for some cats. That does not explain why some cat’s arthritis pain gets better, and some appear to get worse. The EMA warned that the potential existed for cats to develop antibodies against Solensia. That could cause the drug to lose its effectiveness. But that does not explain how they could end up worse than before they took it. Zoetis easily has the wherewithal to explain this problem and, perhaps, even solve it. But it will take neuropharmacologists and pathologists to do so. And since they already have FDA and EMA permission to market Solensia, they have no motivation to do so. Zoetis is an offshoot of Pfizer. Pfizer wanted to market a similar drug, tanezumab, for human arthritis. In March 2021, the FDA voted 19 to 1 against that drug’s approval. But for different reasons. They are not as rigorous when it comes to meds for our pets. R.S.H.  

Dear S.L, I do have some potentially good news for Butterscotch: 10-26-23 M*** M*** 9:40 AM (4 minutes ago) Good morning: I want to provide you with an update on our male cat Jeter. Almost two months after discontinuing the Solensia injections, Jeter has returned to his preinjection self. He is jumping without hesitation. He has regained lost muscle mass in his hind quarters. He is more alert and energetic. For Jeter; we made the correct decision to discontinue the Solensia injections. J.M. & M.M, Las Vegas area

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October 24, 2023

My about 12 y.o. tabby cat, Josie, has a degenerative spinal cord and bone spurs. Her decline has been incremental for over a year and we have managed her symptoms best with prednisone (2.5mg daily). We have tried other pain meds and anti-inflammatories before when we were treating it as an [ ] acute injury.That just didn’t work for her. On Oct 2, 2023 we tried Solensia and began to taper down her prednisone. I was not seeing an improvement by day 6. I also noticed a scab on her chin that I thought she got from her sister but it was a weird scab. So when I saw someone else here post about a scab I thought it seemed more reasonable that it was a side effect of the drug. [ ] Once she was a week off prednisone and 2–3 weeks post injection she got very lethargic and unstable. She was unable to move more than a foot or two in each step before falling. Before the shot she would sometimes crouch or look wobbly but was always able to recover or get to where she was going. [Our] vet had me resume the daily 2.5mg prednisone and we did for 4 days waiting to see the vet again on Oct. 23. During that visit the vet recommended putting her down. [ ] I want to give her 6 weeks post injection. The vet gave her a steroid shot and then antibiotics in case it is a rare bacterial infection. She has been using both heated cat beds available. In the 36 hours since the shot I have seen her respond positively to get back to where she was, able to jump on the bed or couch and walk around. If she can get back to where she was or even a slight decline I think we will not put her to sleep until something else changes. She is brave and loves to be around her people, eat her treats and lay in the sun. If we can keep those elements in her life I am hopeful we can survive the Solensia shot set back. K.L., Josie’s mom, Connecticut

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October 24, 2023

My 18-year-old Siamese mix/moggy, Chris, has been receiving monthly Solensia injections since July 2023. In a few weeks he’ll receive his fifth dose. Before Solensia, Chris would only get up from his bed to eat and use his litter box. His gait was always stiff and his pace slow. Since starting Solensia, I have seen an incredible change in his behavior. Although he still cannot jump, he takes brisk walks around the house. He is brighter and more alert. He also takes more regular trips to the litter box, rather than holding it as long as possible to avoid the pain of getting up. He has also not had an outside-the-box accident since the injections began. I’m over the moon about his progress and hope he continues to benefit from the drug. 

H.S., Massachusetts, USA

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October 11-2023

I wanted to share my experience after getting my 16 year old cat Sage his first Solensia injection to try to help ease his arthritis pain. The injection was recommended by the veterinarian after we ruled out thyroid issues for his meowing and apparent discomfort. He was given the injection on October 3rd. Within 48 hours he declined into a cat completely unrecognizable to me. I had Sage since he was just 8 weeks old and up until this injection he was alert, playful, loving and still active. He could get into his window hammock and loved napping in his cat tree. Over the course of a week after the injection he began pacing the edges of the apartment endlessly, day and night and would just stop when he hit a wall. No reaction, just stuck and staring at the floor. I found him stuck in corners, trapped under furniture and after 3 days it seemed he could no longer see or hear. He didn’t know who I was and didn’t react to his brother. They were littermates and raised together…always wrestling, grooming each other and sleeping together. He now had barely any reaction to his brother grooming him and his brother clearly knew something was wrong. Sage was walking right through water dishes and food bowls as if they weren’t even there and began going to the bathroom on the floor which he had NEVER done once in his entire 16 years of life. completely alert to completely mentally disabled and blind in a matter of days. On the evening of October 9th I found him slumped over and unresponsive behind my hamper and he passed shortly after that. The vet office didn’t give me any kind of warning except for mild soreness at the injection site. I’m devastated and would have just kept him on gabapentin forever to keep him comfortable if I had known the true risks.

D.D., Brooklyn, NY

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October 8, 2023

After my cat Tonka’s first Solensia injection I noticed a scab on his neck under his chin. I didn’t connect it to the Solensia. I thought he just scratched himself. I took him for his 2nd shot on schedule 4 weeks later. Within a few days he was scratching himself constantly and had crusty scabs all over his head and neck. They have developed into sores and he is miserable. If I had known I would not have gotten the 2nd shot. Tomorrow another trip to the vet to see if there is anything to ease his condition. He is 16 years old and was born at my house. I was a foster mom to rescue cats. He is my constant companion.

R. Y., Denver, Colorado

10-9-23 Dear R.Y., In the studies Zoetis submitted to the FDA and EMA to gain drug approval, they enrolled 182 cats, thought to have arthritis, to receive Solensia®. Of those cats, they reported to the EMA that focal pruritus (focal itchiness), dermatitis and alopecia (hair loss) “were common”. EMA defines “common” as more than one cat, but less than ten cats in a group. They also required the boilerplate statement “Do not use in cases of hypersensitivity to the active substance or to any of the excipients” (other ingredients). A very silly statement because we all know that it is impossible to know that ahead of time. In addition to its active ingredient, frunevetmab, aka Solensia contains histidine and polysorbate to keep the ingredients in solution. Histidine can be converted by skin mast cells into histamine.  (read here) Histamine release underlies the urge to itch. Both of those extra ingredients (aka excipients) have, on occasion, been associated with histamine-related itch. (read here) If any of this has anything to do with Tonka’s scabs is something I cannot tell you. Should post injection histamine release be part of his problem, perhaps an oral pre and/or post Solensia antihistamine might be in order. At the first signs of post Solensia itchiness, perhaps claw caps would also be in order. Those are decisions best made by you and your local veterinarian. Best wishes to Tonka and you, R.S.H.

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September 23, 2023

Hi: Our 17 year old cat developed arthritis after recovering from FIP with the help of 84 daily injections of the FIP medication. We heard about Solensia and asked our vet.  She thought it was a good idea. After the 1st injection, Jeter improved.  After the 2nd injection Jeter’s arthritis became much worse. Thank goodness we found this website.  We are discontinuing the injections immediately. Do you know if the negative reaction will reverse itself once the injections are discontinued? Thank you, J.M. & M.M., Las Vegas area

Dear M, I wish I could answer that question. At this point, no one really knows. If Zoetis knows, they are not publicizing it. Solensia (frunevetmab) is an anti-nerve growth factor, an antibody that deactivates a compound, NGF, that in adults plays an important part in sensing pain. To gain FDA approval for Solensia, Zoetis provided Solensia to 182 cats for monthly treatment, and provided indistinguishable sham vials without frunevetmab to 93 cats. Of those receiving Solensia, 12 cat owners reported abnormal behavior in their cats. That included anxiety, hiding, lethargy, inappropriate urination, disorientation, vocalization, or aggressive behavior. Eleven reported post-injection lethargy in their cats, less than a third of the sham cat owners did. Eight of the 182 cat owners whose cats received Solensia reported that their cat’s lameness got worse. Only two of the owners of cats that received sham injections reported that their cat’s lameness (arthritis?) got worse. Solensia and other anti-nerve growth factor medications decrease the amount of nerve growth factor (NGF) in your cat’s body by binding to it. NGF has a protective effect on the brain. (read here) The good news is that when the effects of the injection wears off, I hope that Jeter will return to his same old self. At least the monkeys supposedly did. (1,   2)  

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September 22, 2023

Hi, my 17 year old cat Emma has had 3 shots of Solensia, the last one three weeks ago and now she cannot walk at all. Lameness is listed in Solensia trials and I wish I had found it before I gave my vet the go ahead. Will it wear off after a month? She had no other health issues other than her lameness.

I.T., in the UK

9-26-2023 Is Emma feeling any better yet? 9-30-23 Hi, Emma was PTS on the 28th of September because of a massive worsening of arthritis. Our Vet believes it was an adverse reaction to solencia. At the time of passing she couldn’t walk. 10-23-23 I was sorry to get that news. No one has yet reported to me yet that these side effects wear off. Ron                                                                                                                   

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September 16, 2023

[Her cat, Gwai was 18 years old. She had “mild” arthritis since she was 5 or 6 years old]: I didn’t see any obvious improvement from the Solensia really. The decline after [my cat’s] third Solensia injection was immediate. What my cat, Gwai could do in the morning, she couldn’t do in the afternoon. […] It was like watching someone with brain or nerve damage, or some kind of motor neuron disease. Everyday she would lose more ability to move – she would crawl to the kitty litter unable to lift her limbs properly and I would hold her upright so she wouldn’t tip. Within days she would drag, using only her front legs to get off her heat pad to under the table to wee on wee mats.  In the last days she weed where she was. On the last day [she was] unable to move the bottom half of her body. She was retaining fluid, her limbs were a bit puffy, her back legs inert and stiff. During this time she remained alert and communicative.  She passed on the 7th July. In retrospect, there were earlier signs  – particularly after the 2nd inj., she slowed down, stopped jumping on furniture or onto my knee, didn’t want to walk up stairs, more weight on the front paws than back.

Kind regards, Jackie, Melbourne, Australia

9-17-23 Dear Jackie, I am very sorry to read what occurred with Gwai. Might you tell me how old she was? Was she of a purebred breed? How did your veterinarians account for her rapid decline? Did they suspect some form of spinal tumor, or perhaps cardiomyopathy causing an aortic saddle thrombus to form? Do you feed your cats a diet that is rich in quality red meat? A lack of the taurine present in quality red meat has been known to cause cardiomyopathy in cats that results in clots lodging in the aortic bifurcation to their hind legs or the brain or both. (read here & here) That is not to say that Solensia was not in some way implicated. I just want to understand Gwai’s case better. Best wishes, RSH

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September 13, 2023

Hi, I wanted to let people know about my pet Simba’s experience with Solensia. Simba has arthritis in his hips. He was 13 years old at the time he received his first Solensia shot in August 2022. He received another Solensia shot in October 2022 and December 2022. I’m not exactly sure when he started with symptoms,  but, after crying at night, he started walking around in circles. This was every night. He seemed deaf.  He didn’t acknowledge his name. I took him to the vet after he had had another shot of Solensia in Jan. 2023.  I told her his symptoms and she took his blood pressure. It was high. She said he was acting that way because of his high blood pressure. He just lays there on the floor with his head cocked sideways. He acts like he has dementia. May close his eyes and never puts his head down. He had just had another shot on September the 2nd. 

E.M. @aol.com 

9-17-23 Dear Ms. M., I do not know if Simba’s mental issues are due to Solensia or not. At animal hospitals, blood pressure readings are often elevated due to the “white coat” syndrome – just like in people but worse. Simba is 13, that’s 68 in cat years, and at that age, quite a few health issues tend to begin. If Simba’s blood analysis and physical exams are normal, the only way I know of to possibly identify what is going on is to withdraw each medication that Simba is currently taking one by one, wait a month, and see if you see an improvement in his mental state. There are hardly any medications for humans or pets that do not have potential side effects. You have to decide if the side effects are worth the relief that a medication provides. Veterinarians can’t do that for you. Only you can do that. If you decide to do that, and see any changes, please let me know. Best wishes to you and your cats, R.S.H.

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September 1, 2023

My 12-year-old cat was having arthritic symptoms so I took her to the vet and he recommended trying Solensia. She had her first injection and within days her arthritis seemed a lot better. About five weeks later she had a second injection and within hours her pupils were very dilated and movements very slow. She would not eat or drink, or use the litter box consistently. To say the least, I was extremely worried. We would find her hiding and not wanting interaction or to be disturbed. After about 10 days she started to feel better but very slowly….. We are convinced it was the Solensia, but the interesting factor is that on the first shot she was just fine, and then reacted to the second one. […] Needless to say, we discontinued this treatment, I wanted to let you know what happened in case other people experience the same thing.

L.D., Sent from my iPhone

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August 26, 2023

Hello, my cat got her first Solensia shot about a month ago.  At first everything was fine…and it seemed to help her to limp less.  However, I’ve noticed cognitive changes that I have not seen before..almost like dementia.  She stares into space and has other small cognitive quirks she didn’t have before.  In reading comments on this page, it seems others have noticed cognitive changes as well.  Now, I’m afraid to continue to get these shots.

*****ry@gmail.com, Tennessee

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August 24, 2023

My cat is 2.3 kg and 8 years old, spayed, with a 4 year history of pain from osteoarthritis. She has been on and off gabapentin. It is now 3 weeks following her second Solensia injection and [she] appears more interested in being groomed and jumping from higher surfaces, so I hope to continue the treatment. One thing I am unsure of is she seemed unwell for about 4–5 days following each injection. She is very calm and playful at vet appointments so that leaves me to associate either the Solensia or a coincidental event to her symptoms. Immediately following the appointment she is lively, then day 2-6 [after] she eats less, drinks a lot of water, reduces litter box use to once a day or less (typically 4x daily), itches her eyes and ears aggressively (lasting throughout the month but no sign of alopecia or skin inflammation), is lethargic, and avoids people (typically social). At the last occurrence, I was quite alarmed and brought her to the clinic who did not see it as a concern. I would like to hear if there are other [who’s] cats have shown similar symptoms during treatment, and if the duration/severity of such symptoms changed over time with regular Solensia injections.
B.K., Canada

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August 23, 2023

Spider, [my] 17 year old Siamese has had 5 monthly [Solensia] injections. It has given him years in youth and mobility! I’m sooo pleased and he is moving around freely and a happy little old man! In fact, he seems to get more than the usual 4 weeks out of the treatment! N.P., Carolina Shores, North Carolina

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July 5, 2023

My darling 16 yr old tuxedo, Cleo, received [a] Solensia injection on Jan 24, 2023. Within 48hrs, she was completely altered – much like someone with advanced Alzheimer’s. Totally disoriented and anxious, she paced incessantly unable to recognize obstacles in her path, often walking into corners [and] urinating uncontrollably. She didn’t respond when we spoke to her, petted her, etc…she was unable to sleep and indifferent to treats. None of these behaviors had ever happened [before]. We hoped and prayed the effects would ‘wear-off’ and she’d return to her affectionate, spunky self, but she continued to deteriorate and, after 3 weeks, crossed the Rainbow Bridge.  Allison in NJ

I cannot tell you if Solensia caused this problem. A trip to your veterinary hospital in itself can have negative emotional effects, and elderly cats, like elderly people, often have more than one health issue that can be exacerbated by stress or make them more susceptible to drug side effects. The greater the number of actions a drug has on the body, the greater the variety of possible unwanted effect affect will be. Solensia is unlikely to be any different. Solensia (frunevetmab) is a monoclonal antibody that affects the nervous system by decreasing nerve growth factor (NGF). Nerve growth factor has an enormous number of critical, essential functions in the body. (read here) So, lowering its level in your cat’s body is going to have effects on all of them. Hopefully, the positive effects in your cat will outnumber the negative ones – if any – when they occur. Only you will be able to judge that. Whatever effects Solensia might have on your cat should cease once it is out of its system.

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June 11, 2023

Hello!  Just wanted to let you know that my 13 year old tortie, Zoubi, received her 2nd Solensia injection 2 weeks ago and she is doing amazingly well. She is navigating stairs and revisiting almost all of her old hangout spots. She is herself again. She had some mild diarrhea for the first several days after her 2nd inj which has firmed up fairly well.  Interested to see what happens from here.

6/12/23 After the first inj we saw mild improvement after 2 weeks, moderate at week 3, and significant at week 4. She also gets chiropractor adjustments at each visit which she seems to actually enjoy. She peaked at week 4, and after the 2nd inj had a small backslide. Not sure if it was the diarrhea or if the inj was wearing off. She was back to doing pretty well one week later and amazing at week 2.  She is running up and down the stairs almost too well.  Without the pain, I am aware that she will cause more wear and tear on her joints more quickly, which is a concern of mine, but I am siding with quality of life. She is a big girl at 17+ pounds and receives the 2 vial dose. I am keeping a diary to track her progress. Today she seems a little off. But she had a day or two the first month where she seemed off as well.  Will keep my eye on that. 

C.M., Atlanta, GA area

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June 6, 2023

I was nervous to try a relatively new treatment. I adopted a senior kitty, Mr. Muffins, so didn’t know his baseline, but he was sleeping 18–21 hrs and could spend 8–10 hrs on the same spot.  I noticed his respirations were on the high end, and a google search said that could indicate pain. He appeared to have a limp from the time I got him, but recently started taking two to three hesitations before hopping up on the couch. I went to the vet thinking a physical exam or x-rays, but they recommended Solensia just by my description. I was a nervous wreck the first 24 hrs — he also got a rabies booster, and looked like he felt pretty crummy.  But by day 7, I noticed he was awake more often. Week 2 he was moving around a bit more, with more frequent ups and downs on furniture.  Week 3 he met me at the bottom of the stairs when I got home, and RAN up the stairs when the door opened.  Week 4 he was slowing down a bit, but still was fast enough to elude cuddles…twice.  The increase in type of movement may not be dramatic at this point, but the ease of movement is significant. He appears more comfortable, and those respirations seem slower.  We got the second shot today with no issues.

9/2/2023  So sorry I missed the 60 day update.  But Mr Muffins is going in for shot 5 next week.  He is doing very well on Solensia.  Today he actually did ‘zoomies’ and was running in circles chasing a toy.  He has no hesitations in jumping up on his favorite sofa now, and overall seems to be living a more comfortable and active life.  We have had no complaints.  If anything, I notice he runs out of steam day 25 or 26 (he is right at 15 lb weight), and seems to get same day relief on the day of his shot.

J**********@gmail.com

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April 17, 2023, at 3:43 PM K.S. wrote:

Hi!   I have 2 cats – Callie is a diabetic 13 year old and Tuna is a non-diabetic 15 year old. I started Tuna on Solensia a month ago and am already noticing a difference as we near her 2nd injection in 4 days. She has much more energy and is basically back to bouncing off the walls when she gets the zoomies, isn’t having issues of tipping over in the litter box when pooping, and no longer has trouble jumping or using stairs. Today I spoke with my vet about symptoms I am noticing in my 13 year old- she has never been much of a zoomie cat but recently has become more playful as her diabetes numbers have lowered. In late 2022/early 2023, she went through several hospitalizations for hypoglycemia and then DKA (diabetic ketoacidosis), and is now back on the mend and stabilizing in her glucose levels. I rarely see her jumping up on furniture, and if she does, she takes very measured and calculated methods to get down. I would like to try the Solensia injections in my diabetic cat but can’t find any information on potential effects with diabetic cats. Just curious if anyone has had a diabetic cat on this injection and if they had any issues around diabetes and keeping glucose levels under control? Thanks for any insight!

K. S., Greater Minneapolis/St. Paul, Minnesota.

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On Wed, Aug 3, 2022, at 10:21 AM B.L wrote:

Hi, My sweet cat’s name is Lilly. She is 16 years old and has significant arthritic pain. She is a trooper and still climbs on things but is VERY sensitive if anyone pets her on her backside, closer to her tail. She is scheduled for her first injection in 2 weeks. I’m nervous about potential side effects – from anaphylaxis to uncomfortable itching and fur loss. She has had kidney insufficiency. (she is also hyperthyroid) I understand the studies were only based on 3 months of the medication. What if it exacerbates her kidney disease? I’m really interested to know how other cats have tolerated this medication and if it helped them. I plan to update this after she received her first injection – if I go through with it. Hope some people write in with their experiences soon and hope this medication helps all of our fur babies.

Michigan, USA

February 18, 2023, Dear Dr. Hines, Lilly is doing really well! She has now had 6 injections of Solensia and her pain is much diminished. She is getting up and down stairs better now and climbing more than before the Solensia was started. She can easily jump onto the couch now without hesitation. She no longer flinches at all when anyone pets her back side or when her vet examines her. She was very sensitive there before. He stage 2 kidney disease has remained stable. The hyperthyroidism is well managed, and she is finally gaining a little weight. She seems happy overall and is a delightful kitty. Best, Lisa and Lilly

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On Tuesday, Aug 9, 2022, at 3:34 PM E.M wrote:

Dear Dr. Hines, I am not an expert in the field of Nerve Growth Factor and pain. But I am aware that anti-NGF therapies might have beneficial effects in pain management. Increased concentrations of NGF have been reported in chronic pain conditions such as interstitial cystitis, prostatitis, arthritis, pancreatitis, chronic headaches, cancer pain, diabetic neuropathy, and non-cancer pain. Several early clinical trial have not reported consistent efficacy for anti-NGF drugs in treating pain. However, as you pointed out, Solensia, an anti-NGF monoclonal antibody therapy, has been approved to control feline OA pain. I am not aware of studies investigating the effect of this drug on brain function. So one can only speculate what the effects of lowering NGF level might have on brain function in cats. In primate, rodents and human, a lack of NGF or alterations to it cognate receptors (p75NTR and TrkA) result in cognitive decline in the aged and Alzheimer’s disease brain. Reducing NGF in brain will also have a deleterious effect upon the cholinergic neuron basal forebrain cortical projection system that is dependent upon NGF for its survival. Decrements in NGF would likely activate a cascade of events leading to either cell death in the brain, not to mention the possibility of the formation of brain lesions (plaques and tangles) and long-term alterations to inflammatory mediators within the central and peripheral nervous systems. Since the trigeminal system expresses the NGF low-affinity p75 receptor, reducing NGF may result in unwanted actions.  There may be unexpected actions that are specific to the age of the cat and its medical history.

Take care, E. M., PhD, Chair in Neuroscience, Translational Neuroscience and Neurology, Arizona

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