Feline Asthma And Chronic Bronchitis In Your Cat

 Why Is My Cat Coughing?

Asthma And Chronic Bronchitis In Your Cat

Ron Hines DVM PhD

Although both asthma and chronic bronchitis are lower airway diseases (obstruction occurring deep within your cat’s lungs), some believe that asthma and chronic bronchitis are different diseases that just happen to have similar signs and have similar treatments. I believe that both are just minor variations of the same underlying problem – a hyperactive pulmonary immune system. Feline asthma and feline chronic bronchitis are also referred to by some as feline allergic bronchitis. Some veterinary specialists might suggest that a fluid washing sample (BALF) be taken from your cats lungs. If the debris obstructing your cat’s lung channels contain mostly eosinophils, the pathologist reviewing your cat’s case is likely to call it asthma. If eosinophils are scarce and neutrophils predominate in the sample submitted, the pathologist is more likely to called it chronic bronchitis. The BALF test is known to be prone to errors, but luckily, the same medications help with either condition.

What is Feline Asthma?

When your cat develops asthma, a chronic inflammation of the smallest air passageways in its lungs (the bronchi  and bronchioles) is occurring. It is a form of allergy quite similar to what asthmatic humans experience. During flareups and to a lesser extent between them, the walls of these passageways thicken and narrow. In that situation, inhalation makes them collapse even more, making it difficult for your cat to catch its breath. Not all cats that are having difficulty breathing have asthma. Read about some of those other possible causes  here   &  here). All degrees of feline asthma exist. The symptoms often wax and wane with good and bad days. Triggers for the bad days can be a number of things: house dust mites, chemicals, smoke, stress, dust, pollen, mold. The few studies to identify which triggers are most common in cats were performed using allergy blood tests. Those tests are known for their inaccuracy. (read here)

As I mentioned, although your cat feels better between flare-ups, the lung passage changes that bring on its periodic attacks are ever-present. Those changes consist of increased mucus secretions, thickening of passageway walls, inflammation and an ever-present exaggerated reaction to antigens and irritants that all air contains (= hyper-reactivity and bronchoconstriction).  Because the cat’s entire immune system is hyper-reactive, some of these cats to have itchy skin as well (feline atopy). The lung changes in your cat that eventually led to asthma and bronchitis probably began much earlier than you were aware of. It is rare for this disease to affect young cats severely enough to arouse your concern. That is why it is unusual for a cat to be presented to a veterinarian for an in depth pulmonary (lung) examination before it reaches 3-5 years of age. Some veterinarians and cat breeders believe that Siamese and Himalayan breeds are particularly prone to feline asthma/chronic bronchitis issues. 

What Signs Will I See If My Cat Has Asthma?

As I mentioned, the signs of feline asthma vary from mild to very severe. It depends on how long the problem has been present in your cat, the moment in time when the cat is observed as well as the individual peculiarities of your cat’s immune system. In mild cases or between crises, a mild cough or a squeaky wheeze might be all you notice. Owners sometimes tell me that their cats are less active and playful – probably due to difficulty catching their breath after exercise – but many cats only show a reluctance to move about after exertion or during severe, periodic attacks. You can view videos of typical asthma attacks on

A common error cat owners make is to mistake the cough for a hairball problem. If your cat is a short haired variety,   if brushing does not help eliminate hairballs in a longhair cat,  if petrolatum-based fur ball treatments do not help or if no hair is vomited up subsequent to gagging, asthma or chronic bronchitis needs to be considered as a more likely cause. A small amount of hair in the vomit is not necessarily a sign that the gagging and cough is due to hairballs – asthmatic cats often gag and vomit some hair as well.

The signs of advanced asthma or an asthmatic crisis are considerably more dramatic. These cats are obviously having problems obtaining enough oxygen. Attacks often begin suddenly. These cats are intent on their difficulty and pay little attention to other things around them. They breathe very intently and deliberately and their breaths are labored, rapid, and involve the muscles of their abdomen as well as those of their chest. Expiration – as well as inspiration – of air is difficult for them. When severe, they breath with their mouth open.  It is common for these cat to have their front legs extended forward – as if praying. Without medical oxygen at hand, attacks like these are occasionally fatal. It is very important that cats in this situation not be disturbed unnecessarily in ways that compound their difficulties.

Are There Other Cat Diseases  That Might  Be Mistake For Feline Asthma Or Bronchitis?

Yes:

Heartworms

The symptoms of a heartworm infection are quite different in cats than they are in dogs. (read here) In dogs, the signs of heartworm disease are generally signs of a failing heart. In cats, the signs are generally of lung inflammation – signs that could be easily confused with feline asthma. It is thought that in feline heartworm infections, those respiratory signs are due to the lung inflammation that surrounds dying immature and mature heartworms. Cats are not the heartworm’s natural host so in cats the worms do not live long. All cats that have respiratory signs similar to asthma or bronchitis should probably have a heartworm antibody test (the antigen test is less sensitive in cats) run as well – particularly if they venture out of doors. Cats rarely have heavy adult heartworm infections; but one or two worms are all it takes to cause respiratory distress.

Lungworms

Cats that hunt are occasionally infected with lungworms (Aelurostrongylus abstrusus and others ). This is another peril of allowing your cat to roam freely. Adult lungworms live in the cat’s bronchioles and adjoining areas – the same location where the inflammation of feline asthma occurs. Cat lungworms have been found to be present in many areas of the world. Mature parasites lay their eggs within the lung channels. The eggs hatch there into active larva. Those larva are coughed up, re-swallowed and expelled in the feces. Snails (and perhaps slugs?) are usually mentioned as the carriers of these larva that then transmit them to new cats when a cat eats them. However, many feel that it is more likely that the small bird and mammal prey of outdoor cats are the prime way that cats become infected. It is known that these prey animals can harbor these living cat lungworm larva if they have ingested cat feces while foraging for their food. A small number of lungworms usually cause no visible symptoms in cats. But heavy infections cause signs identical to those of feline asthma. The increased blood eosinophil numbers that are often seen in asthmatic cats occur in lungworm infections as well. These parasites are effectively killed by fenbendazole. So cats that have a history of hunting probably should be treated to be on the safe side – even if no lungworm larva were found in their feces.  Occasionally, lungworm larva, seen in fluid obtained from the cat’s lungs (The BALF exam; read more about that farther down), confirm the diagnosis.

Intestinal Roundworms

Although rare in typical house cat situations, the intestinal roundworm of cats (Toxocara cati) is quite common when cats are maintained in feral, crowded, or unsanitary conditions. (read here) During a portion of this parasite’s life cycle, the parasite’s larva migrate through the cat’s lungs from where they are then coughed up and re-swallowed. Although quite unlikely in a household situation, that could be confused with bronchitis or asthma. As with asthma and lungworms, abnormally high numbers of eosinophils  in blood samples might also occur when a large number of roundworm larva are migrating through a cat’s lungs. Over time, cats with healthy immune systems usually develop age-related immunity to this parasite that keep adult roundworm numbers low. 

Upper respiratory infections or pneumonia

Cats that cough or gasp because of bacterial or viral infections should have other signs that suggest to your veterinarian that asthma is not the underlying cause of their breathing difficulties. Things like eye and nose drainage, the x-ray distribution of their lung disease and lab work results that indicate an infection. 

There are other situations where a non-asthmatic cat might mistakenly be thought to have asthma. All problems that restrict a cat’s ability to obtain enough oxygen might, at first glance, cause somewhat similar signs. Heart problems are high on that list, but there are others. 

What Tests Do Veterinarian Suggest to Decide If My Cat Is Asthmatic?

The symptoms you describe in your cat to your veterinarian – along with tests to rule out the other possible caused I listed – are the hallmarks of asthma diagnosis. Because the diagnosis of asthma in cats is a rule-out process, your vet might also run tests to be sure that heart failure, chest cancer, or even a foreign object lodged in the pets windpipe are not the cause of its breathing difficulties.  Your veterinarian will want to confirm, through x-rays, that your cat’s films show the typical bronchial wall thickening of asthma and bronchitis. Radiologists often call these telltale signs “doughnuts” (read here) or “tramlines”. (read here)

Even if your cat’s x-ray report is normal, feline asthma is not entirely ruled out. Almost a quarter of cats that do have asthma have x-ray results that do not discover it. When no other explanation for their symptoms other than asthma can be found, many vets put those cats on a trial period of corticosteroids and bronchodilator medications to see if their symptoms improve. Response to medication is a legitimate aid to diagnosis when hospital tests do not give you an answer.  Large veterinary centers, with access to CT scanners, might use those apparatus to obtain a more detailed image of your cat’s lungs. Sometimes, subtle changes that indicate asthma or bronchitis can only be seen that way. 

I am not a fan of using small optical scopes to peer into your cat’s lungs. In the majority of cases they will only confirm what you already know – that the small air channels in your cats lungs are too narrow and/or contain excess mucus and debris. But in perplexing cases, instilling a fluid into those channels and then collecting it back for microscopic examination (BALF test)  will give your veterinarian data to help confirm the diagnosis. Restraining cats that are having serious breathing difficulty can be risky. I would only suggest the procedure in perplexing cases that did not respond adequately to standard feline asthma medication after less invasive tests for things that might mimic asthma had all been attempted. Blood eosinophil numbers are elevated in only 17 – 46% of cats with asthma. 

What Medications And Treatments Will Help My Cat?

Veterinarians rely primarily on the anti-inflammatory effects of corticosteroid medications to decrease the inflammation that is making it hard for your cat to breath. They also rely on bronchodilator medications that relax the walls of the small air channels within your cat’s lungs to make air flow easier. Although neither drug group cures asthma, your veterinarian can usually devise a plan using both types to keep your cat’s problem minimized. Some cats will only need those medications during flare-ups.

Corticosteroids

Helpful corticosteroid medications such as prednisolone, given orally to cats, tend to cause fewer side effects than in dogs or humans.  Many veterinarians prefer dispensing prednisolone to cats rather than prednisone although it is uncertain if one is more effective that the other. Never-the-less, side effects from either can occur. They are dependent on the dose given as well as how long your cat will be receiving the medication. When side effects do occur, they are similar to the ones that occur in dogs (or humans) who are producing too much of their own cortisone (Cushing’s disease). They include  increased thirst and increased urination, weight gain and slowed healing.  (read here) Corticosteroids do not give immediate relief like the bronchodilators mentioned below do. Corticosteroids take 48-72 hours to fully work. Asthmatic cats that are overweight and those with concurrent heart disease or diabetes are at considerably more risk from the side effects of corticosteroids. In the many cats that silently carry the feline Herpes-1 virus, viral relapses might be more common as well. 

Some corticosteroid medications are less readily absorbed into your cat’s general blood stream than others. After inhalation, they do their beneficial work locally within your cat’s lungs. Being localized, those products are less likely to produce systemic (body-wide) side effects. Although it is common to begin critically ill asthmatic cats on an oral or injectable corticosteroid like prednisolone, I believe that it is always preferable to use the less absorbable inhaled corticosteroids when it is practical and your cat is more stable. Inhaled products can be the only safe option for cats with some of the concurrent diseases I mentioned. The most commonly used inhaled corticosteroid in cats is fluticasone propionate (Flovent®) delivered through an Aerokat® Feline Aerosol chamber twice a day. A few cats can be maintained with a single daily therapy session. I would avoid frequent use of inhalation products that incorporate salmeterol, a potent bronchodilator. Save it for veterinarian-managed crisis situations. Other veterinarians prefer the inhaled form of budesonide (Pulmicort®). It is another minimally-absorbed corticosteroid marketed for human asthma, rhinitis and IBD.  I suggest that you always begin at considerably lower than the anticipated effective dose and observe its effect on your cat. Doses and programs are given in the various links I have included in this article; but I don’t want you experimenting without your regular veterinarian’s input and supervision. All corticosteroids are potent medications. For instance, in humans, they have been associated with cataracts. (read here)   In cats they have been associated with diabetes. Corticosteroid use can make blood sugar control in diabetic cats considerably more difficult. That is why I don’t believe that mild occasional asthmatic attacks warrant their use in your pet.

There are obstreperous cats that just will not accept pills (prednisolone and prednisone are quite bitter) or inhalation therapy. For those cats a long-acting injectable corticosteroid medication (methylprednisolone acetate aka “Depo” ) might be the only way to deliver a corticosteroid medication to the cat effectively. Vets like me don’t like to do that. Once a long-acting medication is injected, I have no way to stop its activity or lower the dose if side effects begin. Much safer are corticosteroids like prednisolone that are only active for a day or less. Online custom pharmaceutical companies offer many corticosteroids in cream form that you rub on your cat’s ears (transdermal creams and gels). But it is unknown how much of those products actually enter the cat’s blood stream and what the long term effect of those creams on your cat’s ears might be. 

Some cats can be maintained on these corticosteroids alone and at acceptable doses. Other cats require bronchodilators as well (preferably only intermittently during sudden flare-up situations). The use of both together can decrease the dose of each, which, in some cats with other health issues, is a safer option. When your cat has been taking any form of corticosteroid for an extended time and you wish to discontinue giving it, it is always wise to decrease its dose in a step-wise fashion rather than cease giving it abruptly. Orally administered or inhaled corticosteroids take time (days of repeated use) to produce their effects. So starting to give them or increasing their dose during a sudden attack will not be of much immediate help to your cat. For that, a combination of bronchodilator (and perhaps and injectable corticosteroid like methylprednisolone sodium succinate or dexamethasone) might be a better choice. Cats in those situations need close veterinary monitoring. They may need supplemental oxygen as well until those medications take their effect.  Deciding to give your pet any legitimate medication is always a trade off. Any medication that never produces an unwanted side effect probably never produces a desired effect either. Corticosteroids are legitimate medications. They are powerful medications that need to be administered in only the amount that gives your cat a peaceful and contented life. 

Bronchodilators

Unlike oral or inhaled corticosteroids, bronchodilators work rapidly to ease airflow through your cat’s lungs. They do that by relaxing the small muscle fibers located within your cat’s lung channels (bronchioles). So bronchodilators are the only products (other than oxygen) that might ease a sudden attack of difficult respiration or aid in an emergency situation (sudden bronchoconstriction).  In those situations, the most commonly used medication is probably the injectable bronchodilator, terbutaline. When owners are faced with a serious flare-up, inhaled albuterol (aka salbutamol), given during the emergency but not as an every day medication for your cat is probably the most common medication used. There are cat owners who have dealt with this problem in their cats before and who are comfortable obtaining injectable terbutaline from their veterinarian. After instruction by a veterinary nurse, they administer the injections at home when needed.

The use of bronchodilators in asthmatic cats on a day-to-day basis  is controversial. Some feel it might be a helpful adjunct to daily corticosteroid inhalation. Others believe it makes acute attacks more likely and may actually complicate the situation over time.  But because asthmatic attacks in cats are so unpredictable, it can be a hard decision for you and your veterinarian to make. There is very little in the veterinary knowledge base that allows pet owners or veterinarians to make a more informed choice. I feel that these drugs are best reserved to end life-threatening asthma attacks or in a last ditch effort to save cats that just aren’t responding to corticosteroids. All bronchodilators have the potential to cause rapid heart rate (tachycardia) tremors, low blood potassium-related cramps and even seizures when the dose is excessive for the particular animal. (read here) The FDA approved a combination medication similar to albuterol: formoterol, combined with glycopyrrolate, a medication that dries up excess lung secretions. (read here) It is called a Bevespi Aerosphere®. It too might eventually come to have a place in asthma crisis control in cats – but it is too soon for me to know. Some might be tempted to use nebulizers with their cats during an asthmatic crisis or in cats with chronic bronchitis.   That is probably ineffective. It was once a standard treatment for similar problems in humans, but it proved to generally cause more problems than benefits.

Antibiotics

Bacteria (including mycoplasma) are not the cause of feline asthma. But cats with lung problems such as asthma might be more susceptible to bacterial infections that would make their asthma worse. Lungs that contain excess mucus and debris from the chronic inflammation of asthma are great sites for bacterial to grow, unimpeded by the natural immune system cells and ciliary processes that keep lung channels clean. If your cat is taking corticosteroids, those medications also have the ability to lower your cat’s resistance to infection. So there might be times when your veterinarian feels it would be wise to dispense an antibiotic such as doxycycline, or perhaps a fluoroquinolone antibiotic to see if it improves your pet’s breathing function. Antibiotics have no effect on virus. That is also why boarding a known asthmatic cat during you vacations or taking to a groomer is never a good idea. Hire a pet sitter. 

Antihistamines And Novel Anti-inflammatory Compounds

An article by an Oklahoma State University veterinary professor pointed out that neither cyproheptadine, cetirizine, nebulized lidocaine or maropitant are effective in treating asthma in cats. (read here  &  here)  Yet some veterinarians believe that the common, over-the-counter antihistamine, cyproheptadine (Periactin®) has a place in feline asthma treatment. Others do not. The drug’s most common use in cats is in an attempt to stimulate appetite. Occasionally that appears mildly effective. Cyproheptadine should not be given to cats with any indication of liver problems. Cyproheptadine is an antihistamine, but it appears to have effects in cats that influence mood. (read here) Other antihistamines have not proved very helpful for asthmatic cats.

Omega Fatty Acids

Omega-3 polyunsaturated fatty acids (PUFAs) are thought to reduce inflammation throughout the body. (read here) They appear to be effective in reducing the severity of asthma attacks in humans. So it might be a good idea to include a high quality krill or cold water fish oil supplement  in your asthmatic cat’s diet. I prefer human supplements rather than those sold for cats and dogs because quality control procedures for human-intended products tends to be more thorough than they are for animal-intended supplements. 

Other than the medications I have already mentioned, veterinarians have few treatment options for your cat. There are ongoing clinical trials to determine if a drug approved for human allergies (Dupixent®) might help prevent asthma attacks in people. But being a “humanized” mAb, Dupixent® would not be useful in cats. Zoetis has a patented process to rapidly “felinize” humanized mAb medications. But I doubt that there would be a market potentially big enough for them to attempt it. However if Zoetis ever develops a mAb similar to Cytopoint®  which has been “caninized” for dog but instead “felinized” it to treat cat skin allergies, it is quite possible that it would help asthmatic cats as well. Another ongoing human clinical trial in asthmatics is a new medication named Flamboyant 200/12. I do not know anything about that compound. Generally, new effective medications are first developed for humans and then, if veterinarians are lucky, we find that they assist our pets as well. 

Can I Just Have My Cat Desensitize With Allergy Shots? 

If one could cure your cat of all the specific respiratory allergies that it has, one might theoretically cure its asthma through desensitization shots. However I do not know of a case where that was successfully done in cats. The first problem is that blood-based allergy screening tests (RAST tests) are notoriously inaccurate. Too many false positives. Intradermal skin tests give somewhat more reliable results. They are rarely performed on cats. The second problem is that cats with asthma are probably “hyper-responders” – prone to be allergic to many different things. Even the possibly more accurate intradermal allergy tests are likely to miss a few of them. After attempts at desensitization with  shots or oral antigen mixtures, these cats will most likely become allergic to new things as time goes by. 

What Follow-Up And Monitoring Will My Cat Need?

A successful treatment plan will keep your cat’s everyday respiratory distress to a minimum and the frequency and severity of attacks manageable. After 4-6 months on medications that accomplished that, your veterinarian might attempt to give the medications at less frequent intervals and/or lower dose sizes while observing if your cat remains stable. The reverse if improvement has not been as hoped for. The main difficulty in judging the effectiveness of your cat’s current treatment is that the signs of asthma often wax and wane on their own. Sometimes symptoms are seasonal, sometimes symptoms are linked to specific exposure and sometimes cats get better or worse for no apparent reason. So you can never be 100% certain that your cat is better because of the medication it is currently taking until considerable time has passed. As with all chronic diseases in our cats and in us, drug doses and lifestyle management need to be revisited now and then. Options that were not available once might be available now. A yearly blood chemistry  panel and CBC are wise for cats receiving asthma medications on a day-to-day basis. Blood chemistry and CBCs are also advisable any time there are indications of decline in your cat’s health or a significant weight change.

 

A quality scale to weigh your cat and a weight diary that you keep can often detect health issues sooner than sophisticated veterinary tests or office call visits. Your cat’s appetite is closely linked to its general health. Weight creep-up, which you can manage by restricting its calorie intake (read here), increased appetite, weight gain and fluid retention are common side effects of corticosteroid medications. Compounding that is that some asthmatic cat’s avoid exercise. Unintended weight loss is of concern as well. As I previously mentioned, inhaled puff corticosteroids  tend to cause less of these side effects than those that are given by mouth or by injection.  

Are There Things I Can Do To Make Repeat Attacks Less Likely?

Although easier said than done, try to remove as many possible asthma triggers as possible. Remember that it is unusual for one single item to be responsible for all of your cat’s symptoms. Services that offer air duct cleaning rarely improve room air quality. But using a portable air cleaner and/or upgrading the air filter in your heating/AC system often does improve indoor air quality.

If you suspect that a certain brand of cat litter is one of the causes, replace it for two or three weeks with shredded newspaper or dust-free sand. If the cat’s condition improves you can try new brands of cat litter later. Cats can be sensitive to the strong odors of cleaning agents, smoke, sanitizers, perfumes and the like.  Any of suggestions you see on websites that pertain to avoiding the triggers of human asthma might be beneficial to your cat as well. 

Can My Cat’s Asthma Be Cured?

I do not believe that cats can be cured of asthma. I would avoid any products or professionals that would offer you that false hope. 

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