Pain Control In Your Dog And Cat
Ron Hines DVM PhD
You should never give your pet any of the medications I write about without expert, hands-on advice from your local veterinarian. Do not give doses higher than recommended. Do not give your pet medications that are just sitting around your house and do not mix medications without first discussing it with your veterinarian. Any medication that is powerful enough to stop pain is also powerful enough to cause serious side effects when it is given to an animal for which it was not intended or in too large a dose.Your veterinarian job is to supply you with options and medications, your job is to decide which ones give your pet the most relief. Best wishes, RSH
If we love a pet, we know that it experience the same pain that we do. I will never be able to prove that, scientifically; but all of us who care for animals know instinctively when our pets are troubled, uncomfortable or in pain. The intimate bond between a pet and its provider mean that you are the most likely person to notice those signs when they are present. It’s you, not your veterinarian, who needs to be your dog or cat’s advocate when it is receiving veterinary care. And its you, not your veterinarian, who should decide when pain medications are working and when they are not. When they are required and when they are not.
Some pain is temporary (acute) and some is persistent (chronic). Your veterinarian has more medications at his/her disposal to treat acute pain in your pet than to treat chronic pain. Acute pain results from surgery or sudden damage to any of the major organs, muscles or bones of your pet’s body. Surgery, accidents and sudden organ inflammation are the most common cause of acute pain. Degenerative joint disease (arthritis) and cancer are the most common causes of chronic pain in pets.
All pain-relieving drugs are called analgesics. It’s not just a matter of making your pet more comfortable – controlling pain actually allows your pet to get well sooner. Whenever it is possible, it is better to give pain-controlling medications early rather than waiting until the pain becomes severe.
Pets and humans experience the same pain and react the same to pain-relieving medications. We can’t ask your pet how it feels; but we can ask human patients how much better they feel after receiving pain-control medications. That’s why, whenever I can, I make my decisions and recommendations on what works best in people. Even then, pain is such a complicated phenomenon. So many things go into how you or your pet is feeling that it is extremely hard to decide the actual effect of any one thing. Even your pet’s sex ( read here & here ) sunshine ( read here ) and age ( read here ) influence reactions to pain. I am convinced that dogs breeds that were bred to fight or perform heroically are more tolerant of pain. (It occurs in other animals as well). ( read here )
When you take your pet to an animal hospital, your pet will be preoccupied, worrying about the strange scary environment. It may ignore the pain that you noticed at home. This can be very frustrating for owners who tell me “but he was limping at home!”
Signs of pain are more subtle and hard to notice in cats than in dogs. The most common sign of pain in cats is a reluctance to move. Some will hiss or growl when a painful site is touched. Others just become unresponsive to your affection. There are cats that become aggressive and belligerent when they are in pain and most will eat less. Many will groom more. Some carry their ears lower and others just meow pathetically.
In any pet, behavioral change, trembling, hiding, restlessness panting, salivation, licking of the lips , dilation of the eyes , aggressiveness, increased heart rate, loss of appetite, a tucked up tummy, lameness and limping or self-mutilation can all be signs of pain.
It is hard for veterinarians to judge the severity of your pet’s pain, When I am uncertain, I often pinch the front toe of a pet that might be in pain to judge the severity of its pain. If the cat or dog reacts to the toe pinch as I would, then I assume the severity of its other pain is probably less than that of the pinch. We only have crude methods when our patients can’t speak.
Pain alone can actually change the results of blood chemistry analysis . Dogs and cats in pain can have elevated blood sugar. Their blood cortisol ( a natural corticosteroid ) and white blood cell numbers often increase too. Pain can also interfere with your pet’s immune system, increase the risk of infections and slow the healing of wounds and surgical incisions. So removing your pet’s pain is not just a matter of making it feel better – its important for it to get better. The total elimination of pain may be impossible or even undesirable in your pet. Any medication that effectively blocks pain has undesirable side effects as well. But we can minimize pain in your dog and cat with a number of medications.
There are five major classes of medicine that can be used to control pain in dogs and cats. Cats do not metabolize many of these drugs as well as dogs do, so safe options for your cat will be fewer and your veterinarian will be more cautious.(ref)
All of the medications I discuss must be used with extreme caution in cats. You and your veterinarian must weigh the advantages of pain medications in your cats against the possible damage that might occur.
There are some general rules when using pain control medications in dogs and cats. The first is to give the medication early, before the pain becomes too intense. The second is to give lower doses of two or more pain control medications that have different modes of action rather than a higher dose of a single medication. Often, what we call a “second tier” medication that is weaker but has fewer side effects is added to a “first tier” medication that is more powerful (but more dangerous) in order to keep the first tier drug dose low.
Doses need to always be kept to the bare minimum that gives your pet acceptable relief. Older patients generally need lower doses less frequently than younger, more robust, pets. Its also wise to check your pet’s kidney and liver function before and during the use of most pain control medications.
The Non-steroidal Anti-inflammatory Agents (NSAIDs) :
This section pretty much repeats the information in another article I wrote on managing arthritis in older dogs. That article discusses safer, non-drug , option to help pets in pain. You can read that article here.
Cats do not tolerate the long term use of NSAIDs of any kind well. The only approved NSAID for cats through 2020 in the United States is meloxicam (Metacam®) ; and it is only approved for a single post-surgical injection to relieve pain. The dose must be exactly correct for the cat’s weight. If it is given longer to cats, it has been known to cause severe kidney damage. Some of these unfortunate cats can be saved with intensive intravenous fluids given for a number of weeks, but some of them can’t
The Side effects Of All NSAIDs
NSAIDs are all very effective in treating chronic pain. They work better when the pain is due to inflammation, such as arthritis, than when it is the nerve-generated pain of spinal cord related issues. All newer NSAIDs work well in dogs. All are relatively safe when they are given according to the manufacturers directions. But all have the potential to produce, occasional, severe side effects. Usually, those side effects occur when too much was given, when it was given too frequently, or when it was given combined with certain other medications. But sometimes, serious side effects occur when the NSAID was given exactly as the FDA-approved label on the product suggested.
All NSAIDs can have negative (harsh) effects on your pet’s digestive tract. Although NSAIDs can affect many of your pet’s organs, its stomach and intestines are the most sensitive. When digestive tract problems do occur, your dog will probably loose its appetite. It may develop diarrhea and its stool may become dark and tarry (from digested blood). NSAIDs also have the potential to slow your pet’s blood clotting process.This can leading to uncontrolled bleeding. Even pets that have no visible bleeding problems when taking NSAIDs have a slower blood clotting time. ( read here ) NSAIDs do affect blood supply to your pet’s kidneys. So on rare occasion they have the potential to make existing kidney problems worse and possibly cause new ones.
NSAIDs should not be given when your pet is on certain other medications. (Such as prednisone, dexamethasone or other corticosteroids) If your pet is taking phenobarbital for seizures, its liver function needs to be carefully monitored and the doses of heart medications (enalapril, benazepril, etc.) might need to be adjusted.
It is safest to have a “rest period” between switching from one NSAID to another. We are never certain how long some of these drugs linger in your pet’s system. I always try to give NSAIDs with food. You won’t see the drug effect on your pet immediately. Wait up to 8 hours to see full effects of the first dose and up to 10 days to see its long-term effect on your pet’s pain.
No one has ever proven that any one of the newer NSAIDs is more effective than another. But if one brand does not appear to be effective in your pet, try a different one. Absorbability and formulations differ between manufacturers and products. However, if you pet has had a severe side effect to any NSAID, be extremely cautious if you attempt to use another. If you give an NSAID medication in liquid form, be sure to shake the bottle well.
NSAIDs will, on rare occasion (perhaps one in 1500 dogs, no one really knows) , cause severe gastrointestinal bleeding liver or kidney damage. When it is the intestines that have been damaged, the pet will stop eating, vomit and have diarrhea and its gums might become pale (anemic). The problem with liver or kidney damage is that by the time signs are visible to you, the damage has already been done. Intestines are capable of rapid healing – livers and kidneys are not. When it is the liver that is affected, the dog’s gums and the whites of its eyes may turn yellowish in color (jaundiced). When the kidneys have been damaged, the dog might become depressed (uremic). You can read about kidney disease and uremia here.
Although these type of problems are rare, they do occur and they are never “rare” when they occur in your pet. It is nearly impossible to predict which pet might experience these severe side effects. They can occur suddenly and without warning – but usually within the first few weeks of use. Dogs differ in how they metabolize NSAIDs. Fast metabolizers dispose of the drug rapidly – sometimes too rapidly to benefit from it. Slow metabolizers allow the drug to build up to toxic levels in their system. The vast majority of dogs are somewhere in the middle – and safe.
A few dogs develop a dry eye problem ( keratoconjunctivitis sicca ) due to NSAIDs. These are often pets that already had marginal tear production and when it occurred was usually the NSAID drug, etodolac (Etogesic®), that was implicated. ( read here )
It is safest when all dogs that plan to be on an NSAIDs program have a blood chemistry/hematology profile run prior to beginning their pain medication program. That is especially helpful when base line liver and kidney test values are checked prior to beginning these medications. That is so your veterinarian will have a reference point to refer to if drug issues develop later on. It is safest to have those same tests repeated every six months to monitor how your pet is handling its pain-relieving medications.
Inform your veterinarian of any change in your pet after it begins NSAID treatment. When serious side effects do occur, it is often that too much of the medication was given for the pet’s body weight, that its body weight dropped or that the pet was given additional medications (such as aspirin or Advil®). But occasionally, side effects occur when you give these medication at exactly the dose suggested and prescribed. When that happens, the dose needs to be lowered below the manufacturer’s suggested dose or another medication needs to be substituted. Don’t start giving NSAIDs after mid-week. Start on a Monday or Tuesday, so your regular veterinarian will be available if problems occur. Emergency hospital visits are never pleasant.
I know I began with really scary side effects. Just remember, NSAIDs have an excellent track record for safety in dogs. Recent studies using activity monitors found that these medications boosted the activity level of arthritic pets by about 20%. The use of any drug is a trade-off between risks and benefits and the NSAIDs are no exception. The only way you will entirely avoid the risk of medication side effects is to use treatments that don’t do anything one way or the other – like Wellness-New Age medicine, naturopathic, homeopathic, complimentary and chiropractic medicines and therapy.
These alternative therapies do have real benefits for some pets and their owners – they keep the pet safe from the side effects of real drugs they did not really need, they avoid the dangers of over-medication and they offer comfort and emotional support to worried owners, concerned over the health of the pets they love.
What Are The Most Popular NSAID Medications Available For My Pet?
All NSAIDs decrease the body’s production of prostaglandins, one of the main drivers of pain associated with inflammation. They do so by blocking enzymes involved in prostaglandin formation (COX enzymes).
Modern NSAIDs are selective in which COX enzymes they block. The earlier, “first generation” NSAIDs, ones, like aspirin and ibuprofen, are not selective in which of the COX enzymes they block. The block the good with the bad, so they produce greater side effects. That is why I don’t suggest that you give any of them to your dog and certainly not to your cat. The only one I discuss later is piroxicam (Feldene®) because there are pet owners around the world who can’t afford the safer, but more expensive, newer ones designed for dogs.
These more modern NSAIDs block a specific COX enzyme (COX-2) that is chiefly involved in the production of inflammatory prostaglandins. These are the NSAIDs you see advertised on the internet and sold by veterinarians for dogs. There is no proof that any one brand is more effective, or causes less potential side effects than another.
The Newer NSAIDs:
Don’t expect to see the full effect of any of the following NSAID medications for about a month after you begin giving them. ( read about that here )
Rimadyl® (Pfizer Pharmaceuticals, carprofen, Novox® etc. generic)
This was the first modern NSAID to become available for dogs in the United States (in 1997). It comes in an injectable form, caplets and chewable flavored tablets. It was initially sold by Pfizer and is now marketed by the Pfizer spin-off, Zoetis. Carprofen is off patent and available in a variety of generic brands.
Deramaxx® ( Elanco Pharmaceuticals, deracoxib )
This medication was released in the United States for use in dogs in 2002. It is still widely used in dogs to treat the pain associated with osteoarthritis. The flavored tablets provide about 24-hour control of pain and inflammation with a single, daily dose
Metacam® (Boehringer Ingelheim Pharmaceuticals, meloxicam, Mobic®, Mobicox®-Canada )
Boehringer Ingelheim was already studying this drug in 2000 as a potential anti-inflammatory drug in humans ( read here ) It was available for use in dogs in Europe and Canada from the early 1990s and in the US, from 2003. It is one of the few NSAIDs approved for one-time, one-injection, use in cats.
Previcox® (Boehringer Ingelheim Pharmaceuticals, firocoxib , Equioxx®=horses)
Previcox was Merial Pharmaceutical’s entry into the dog NSAID market. Since Merial was bought out by Boehringer, Boehringer now markets two competitive products. Previcox® was been approved in the United States in 2007 (although it was already being used in European dogs in 2004). It comes as a chewable tablet. Although Merial developed the product specifically for dogs, it does not appear to be any better than carprofen or meloxicam in preventing pain or lameness ( read here ) .
Flunixin meglumine (Banamine®, Schering-Plough, etc)
Flunixin meglumine is a potent injectable NSAID, which is particularly good for intestinal pain. In the United States, it is approved only for use in livestock. Veterinarians have use it off-label to treating the pain associated with parvovirus intestinal disease in dogs and for treating post-surgical and stomach pain. It must be used very cautiously in cats. It is only FDA-approved for use in livestock.
Zubrin® (tepoxalin, Schering-Plough/Merck/Intervet)
This NSAID was initially investigated as a possible anti-cancer medication. Several years later it was developed as a possible anti-inflammatory drug for humans. It is no longer approved for use in the United States due to the numerous complains the FDA received regarding its side effects. I am unsure of the drug’s current status in Europe or the UK.
EtoGesic® ( Etodolac Ft. Dodge/ Wyeth human form= Lodine®, also generic)
Of all the NSAIDs approved for dogs, dry eye (although quite rare) is most associated with EtoGesic®. ( read here ) If your dog is one of the breeds particularly susceptible to dry eye, or if it has already experience dry-eye in the past, a schermer tear test prior to beginning EtoGesic® would be wise. .
Other Pain Control Options
In a 40-dog study, tramadol was not effective in relieving the pain of elbow and knee arthritis in dogs. ( read here )
Tramadol is a medication that receives a lot of attention as a possible safer alternative to NSAIDs or narcotics for pain control in your pet. It’s side effects seem to be considerably less than the potential ones of NSAIDs, traditional narcotics or corticosteroids. The medication is inexpensive. Unlike NSAIDs, tramadol is thought to work directly on pain sensation within the brain, not on the source of the pain itself. Veterinarians have been dispensing tramadol in an attempt to control post-surgical pain and, sometimes chronic pain. You can’t ask your pet if a drug is effectively reducing their pain. Tramadol appears to help some people experiencing long-term pain but not others. We know less about possible long-term toxicity when it is used in cats. Perhaps will turn out to be an effective alternative to NSAIDs. Pets with liver or kidney disease or taking anti-anxiety medications probably need to have their doses of tramadol lowered. In humans, its pain-relieving abilities were no better than Tylenol®.
Gabapentin is sometimes effective in controlling chronic pain in humans, particularly the neuropathic pain of spinal cord injuries. It might have a place in chronic pain management in pets as well. The one study I know of that looked at its use in dogs with acute pain, found it was not helpful. ( read here ) Another study looked at its use in cats subjected to thermal pain. It was not helpful there either. ( read here ) Gabapentin is not an FDA-approved medication for pets but it is occasionally dispensed.
Methocarbamol is a centrally acting muscle relaxant, not a pain-killing analgesic. But veterinarians occasionally dispense it when they think that muscle spasm might be a part of your pet’s pain problem. It is a safe medication. So if your pet suffers from spinal pain, you might discuss incorporating methocarbamol in its treatment plan.
Like muscle relaxers, corticosteroids (glucocorticoids) do not control pain. They are, however, the most potent anti-inflammatory drugs known. All of the synthetic corticosteroids (prednisone, prednisolone, dexamethasone, etc.) mimic the effects of the body’s own cortisol which is produced by your dog or cat’s two adrenal glands. (There is an explanation of that process in my article on Cushing’s disease) Corticosteroids, through their down-regulation of inflammation, tend to reduce pain. However, all corticosteroids have major side effects when given over extended periods of time. These changes include, weight gain, fluid retention , increased thirst and urination, thinning of the skin, bone loss, liver changes, decreased resistance to infectious disease, mood swings, and increased blood sugar. When there is no alternative to their use, they should be given in the minimal amount that will control inflammation and they should not be given more than two or three times a week – at most. Corticosteroids are a legitimate end-of-life option when owners and pets want a few more pain-free months together.
Controlled Substance Medications (Narcotics)
Injectable and oral forms of opiates are rarely dispensed for pets in the United States. In the US, the Drug Enforcement Agency (DEA) frowns on any long-term use of opioids, fearing they might be diverted to illegal human use. The DEA lists all the strong opiates as CII (Class-2 narcotics). Most veterinarians fear prosecution by the DEA and use them as briefly in pets as possible. Because cats are deficient in glutathione liver enzyme, the half-life of some opioids in cats may be prolonged and doses must be considerably smaller.
Opiates or opioids are the most powerful pain-relieving compounds available for pets. They all mimic natural brain chemicals that limit the perception of pain. However, they are highly addictive and should be reserved for pain that will not respond to other medications. . Also, with time, doses have to be increased to obtain comparable pain relief. Side effects can include bizarre behavior similar to the euphoria (joyous feeling) seen in humans taking these meds, depression of breathing , physical dependence, slowed heart rate constipation and itching. Opiate narcotics may also cause contraction of the pupils of the eyes, sedation and unusual taste in foods. In humans, they are generally given to alleviate the pain of terminal cancer or painful nerve conditions. In pets, they are given to lessen post-surgical pain, and the pain of trauma, or to combat the pain of arthritis and cancer when all other medications fail.
Fentanyl Patches (Duragesic® Janssen Pharma)
Veterinarians use this narcotic to alleviate post-surgical pain in pets ( read here ) and to treat the pain of terminal cancer. It is about 100 times stronger than morphine. Only a few veterinarians dispense it for severe arthritis when NSAIDs fail. Most would rather gain a few more months of pain-free life for your pet by giving it corticosteroids. However, fentanyl has advantages in many dogs and cats over corticosteroids in relieving end-stage pain. Fentanyl is not a drug to be used in your pet lightly. It is not, and never will be , a first line treatment for arthritis. But it can be a last ditch treatment for your pet to gain precious pain-free time. After a fentanyl patch is applied to your pet’s skin, its intense analgesic (pain-canceling) power can block pain for up to three days. There is a price to pay for that. Fentanyl is an opioid narcotic. All opioid narcotics can cause mood changes, sedation or restlessness in pets and humans. They are also powerful depressors of respiration and the nervous system, so your pet can pass away from respiratory failure (not breathing adequately) or circulatory collapse if the dose is too high or your pet is already too debilitated and weak. There is an antidote for these effects – Naloxone (Narcan®). So pets placed on fentanyl should be hospitalized under close watch for the first 48 hours after beginning the patch or the dose should begin very low and only be increased very gradually over a period of weeks. All control narcotics can cause mood change (dysphoria), whining and restlessness or depression and these are the side effects that bother pet owners most. Sometimes these problems lessen over time as the pet becomes used to the medication. Dogs that are running fevers can absorb the drug too quickly from the patch and any form of external heat (such as a heating pad) – can release it suddenly. Other drugs your pet may be taking can also influence how fentanyl affects your dog (Cushing’s disease and cognitive dysfunction medications, mood-altering drugs, tranquilizers, sedatives etc.). Dogs are resistant to the effects of all opioids. So typical human doses have no bearing on what an effective dose will be in your pet. Being a federally controlled substance, there is a lot of paperwork involved for your veterinarian and you will have to deliver and pick up the fentanyl prescription in person at your pharmacy.
Patches may cause irritation to your pet’s skin where they are applied. That problem tends to get worse with time, but it can be managed with soothing ointments. The patch is very dangerous if your pet swallows it. There is a great deal of variation between pets in the amount of medication they will absorb so always begin by giving your pet less than you think it will need.
Butorphanol (Stadol®, Torbutrol®, Torbugesic-SA®, Ft. Dodge/Wyeth)
Butorphanol, a mixed pain-receptor blocker is weaker than many narcotics, so, it is less likely to cause some of the respiratory depression that stronger narcotics might produce. Because of its greater safety, it is a bit more loosely regulated by the DEA (C-IV). Butorphanol is not used much to treat chronic pain in pets because its effects are so short-lived. This is one of the few opioid drugs that works consistently well in cats. It can be administered by injection or intranasal spray. It has been given to dogs and cats by injection, up to three times a day. It takes about 20 minutes for its pain-controlling properties take effect and lasts for about eight hours. It can also be given by mouth. It causes fewer side effects than traditional opioids narcotics. Occasionally, butorphanol will cause eye dilation, confusion and pain at the site of injection – especially when given to cats. It is not considered to be useful in the management of chronic pain. Compounding pharmacies can prepare a trans-dermal gel of butorphanol that can be applied to the inner surface of your pet’s ear or a shaved spot on the neck. The injectable liquid butorphanol has also be given orally to cats. Since it has no taste, cats will not fuss about a bitter taste. It is not absorbed well when given in this manner to dogs. Possible side effects are loss of appetite, vomiting, incoordination, and restlessness. Butorphanol is also a good cough suppressant. It’s effects are similar to codeine. It is a good post-surgical medication for cats.
Buprenorphine (Ceva Animal Health, Vetergesic® Buprenex®, Temgesic® )
Buprenorphine has been used to relieve post-surgical pain in dogs. ( read here ) It is a medication with few serious side effects at accepted doses. It works best when pain is no more than moderate. It can be given as oral drops, by injection or it can be prepared by compounding pharmacies as a transdermal patch to be administered through the skin – similar to fentanyl.(ref) Although these patches take up to six hours, to work, they can maintain a pain-controlling effect for 6-12 hours. With subsequent patches, pain control becomes more uniform.
There are many other approaches to short-term relief of surgical pain in pets that I do not have the space or time to cover. On of them are nerve blocks with long acting numbing agents, like bupivacaine. ( read here )
God did not give our pets exceptionally long lives. But he did bless them in other ways: They do not worry about tomorrow or fret about yesterday like you and I do. They live in the here and now. That, and their devotion, is why we love them so much. Sometimes, all your pet really needs in its autumn years is extra love, and some of the non-drug suggestions in my article on arthritis .