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What is Feline Asthma ?
Although both asthma and chronic bronchitis are lower airway diseases (= occurring deep within the lungs), in cats, asthma and chronic bronchitis are two different diseases that produce similar signs and have similar treatments. Because of that, I’ll try to explain them both in this single article. The short explanation of chronic feline bronchitis follows the portion devoted to asthma – so scroll down to it if that is your interest.
Asthma in cats, as in us humans, is a chronic inflammation of the smaller passageways of the lungs (the bronchi and bronchioles). It is a form of allergy. When your cat has asthma, the walls of these passageways thicken and narrow. In that situation, inhalation makes them collapse even more, making it difficult for your pet to catch its breath (many things other than asthma can affect the ease and rate of your cat's breathing [ref1, ref2]). All degrees of asthma exist in cats and symptoms often wax and wane with good and bad days.
But although your cat appears better between flare-ups, the lung passage changes that bring on the periodic attacks are ever-present. Those changes consist of increased mucus secretions, thickening of passageway walls, inflammation and exaggerated reaction to inhaled antigens and irritants (= hyper-reactivity and bronchoconstriction).
The lung changes that eventually led to the asthma and bronchitis probably began much earlier, in your cat’s youth. But it is rare for the disease to affect young cats severely enough to arouse owner concern. That is why it is unusual for cats to be presented to veterinarians for a thorough pulmonary (lung) examination before the pet reaches about 3-5 years of age.
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 attacks on .
A common error owners make is to mistake the cough for a hairball problem. If the cat is a shorthaired variety, if brushing does not help a longhair cat, if petrolatum-based fur ball treatments do not help or if no hair is vomited up subsequent to gagging, asthma or bronchitis needs to be considered. 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 as well.
The signs of advanced asthma or an asthmatic crisis (“status asthmaticus”) 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 forelegs 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.
The symptoms of a heartworm infection are quite different in cats than they are in dogs. (ref) In dogs, the signs of heartworm disease are generally those of a failing heart. In cats, the signs are generally of lung inflammation - signs that could easily be 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. So 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 are all it takes.
Cats that hunt are occasionally infected with lungworms (Aelurostrongylus abstrusus and others ). (ref) 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, reswallowed 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 the 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 food. Small numbers of lungworms usually cause no visible symptoms in cats. But heavy infections cause signs identical to those of feline asthma. Even 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), make the diagnosis.
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. Some are discussed here.
Considerably more research has been done by physicians on the underlying changes occurring in human asthma than veterinary research studies of cats with asthma. Although it is tempting for veterinarians and cat owners to consider them close to identical – we really do not know that for sure.
In cats, the problem appears to be closely linked to errors in the pet’s immune system. That is, mistaking common air contaminants for threats to the body. That is also a general definition of allergies of all kinds. Some cats, and some people, are just born with immune systems that are more likely to make those mistakes than others. In feline asthma, antibodies (IgE) are produced against these inhaled contaminants (pollens, mold, insect dander, etc. = aero-allergens). Some cat owners and veterinarians list tobacco smoke, dusty cat litter, fireplace smoke and various sprays and cleaning solutions as triggers. That is plausible - but no hard scientific information exits.
Resident immune system cells (mast cells and eosinophils) then release compounds (cytokines, etc.) that result in inflammation of the tiny passages and channels that make up the lung. Due to this inflammation, those passages become narrower. Their walls thicken. They become occluded with mucus and cellular debris and the cat has difficulty obtaining enough air (oxygen). The smooth muscle that make up a portion of the channel walls can go into periodic spasms (bronchoconstriction). That probably contributes to the flare-ups that you see in your cat. Severely inflamed lungs can also be too “wet” (edematous). That further limits the amount of oxygen the cat is able to obtain. Asthmatic lungs are sometimes described as “hyperresponsive”. That means they react in an exaggerated fashion to the air contaminants that a cat would normally inhale.
For reasons I can not tell you, some cats do not experience these flare-ups frequently. In those cats, the only evidence that there is a problem is a chronic cough.
Despite my simplified explanation that feline asthma concerns antibodies (IgE), eosinophils and mast cells, it is considerably more complex than that and neither veterinarians nor physicians completely understand everything that is occurring. Many compounds and cells play a part in the inflammation that an asthmatic cat experiences.
Any change in your cat’s environment or the contents (or temperature) of the air it breathes are thought to be capable of triggering an asthmatic attack. Episodes of asthma can also be triggered by allergens in the air or stress. Some common allergens are grass and tree pollens, smoke, fumes, cigarettes, dust, and aerosols of various sorts such as perfumes, deodorants and flea spray. When these cats contract bacterial, mycoplasmal or viral respiratory disease their problem can become much worse than it would be in a non-asthmatic cat. Heat, cold and exertion can all trigger an attack as well.
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” (ref) or “tramlines”. (ref)
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 is present, 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. (ref)
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 are only seen that way. But like the procedures I describe next - broncoscopy to peek into the small channels of your cat's lungs and washing out those channels with fluid to obtain samples of the cells they contain (bronchoalveolar lavage cytology BAL) - restraining a cat with breathing problems in the CT apparatus can be risky. The cat is likely to become frightened and agitated and could collapse during the procedure. That is why many veterinarians opt to try proven asthma medications and hold off on these tests unless the response to the medications was not satisfactory.
I am not a fan of using small optical scopes to peer into your cat’s lungs either. At the most, they will 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 for microscopic examination (BAL = BALF test ) will give your veterinarian data to help confirm the diagnosis. As I mentioned, restraining cats for this procedure can be risky in itself. I would probably only suggest the procedure in perplexing cases that did not respond adequately to standard feline asthma medication when tests for things that might mimic asthma had all been negative. If the washings contained primarily eosinophils, little was gained. We would be left wondering why corticosteroids did not improve the cat’s condition. But if the washings contained primarily neutrophils a case of chronic bronchitis would be more likely. If the washings contained evidence of fungus, bacteria, or mycoplasma, we would know what the underlying cause of the cat’s breathing difficulties were as well. (rptref1, ref2)
Eosinophils also circulate in your cat’s blood. But blood eosinophil numbers are elevated in only 17 –46% of cats with Asthma. (ref)
There are also what are called “provocative tests” that have been suggested as means of diagnosing feline asthma. (ref) I would personally find it cruel to subject someone's loved cat to those sort of procedures.
These last tests are generally performed in veterinary teaching institutions where inquisitiveness and scientific advancement have been known trump individual patient outcomes. But if it wasn't for that academic inquisitiveness, veterinary medicine would not have come as far as it has and I wouldn't be able to write this article.
Veterinarians rely 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 medications that relax the walls of the small channels within the lungs to make air flow easier (bronchodilators).
Although neither drug cures asthma, a plan using both can usually be developed to keep the cat’s problem minimized. Some cats only need them during flare-ups.
Corticosteroid medications such as prednisolone, given orally to cats, tend to cause fewer side effects than in dogs (veterinarians prefer to use prednisolone rather than prednisone in cats. When required, dogs and us humans do well on both). Never-the-less, side effects can occur. They are dependent on the dose as well as how long the cat must receive the medication. When side effects do occur in cats, they are similar to the ones that occur in dogs (or humans) who are producing too much cortisone (Cushing’s disease) – increased thirst and urination, weight gain, slowed healing, etc. (ref) (Corticosteroids do not give immediate relief like the bronchodilators mentioned below, they 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 cats that silently carry the feline Herpes-1 virus, viral relapses might be more common as well. (ref)
Some corticosteroids are less readily absorbed into your cat’s blood stream than others – yet still able to exert their beneficial effect when given by inhalation. It is common to begin seriously asthmatic cats on an oral or injectable corticosteroid (like prednisolone). But I always prefer using inhaled corticosteroids when that is practical and the cat is 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 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 the inhalation products that incorporate salmeterol, a bronchodilator, saving them for veterinarian-managed crisis situations.
Other veterinarians prefer the inhaled form of budesonide (Pulmicort®). Both products are marketed for human asthma. Physicians generally consider them about equal in potency – but be cautious when switching between steroids. Always start 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. (ref) In cats, with diabetes, corticosteroid use can make blood sugar control considerably more difficult. So 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 is 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 effectively. Vets like me don't like to do that. Once that 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 act for a day or less.
Some cats can be maintained on corticosteroids alone. Others 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 stepwise fashion rather than cease giving it abruptly. Orally administered or inhaled corticosteroids take time (days of repeated use ) to produce their effects. So giving them or increasing their dose during a sudden attack will not be of much immediate help to your pet. 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.
Deciding to give your pet any real medication is always a trade off. Just about any medication that never produces an unwanted side effect probably never produces a desired effect either. Corticosteroids are real medications. They are powerful medications that need to be administered in only the amount that gives your cat a peaceful and contented life. (ref)
Unlike oral or inhaled corticosteroids, bronchodilators work quickly to ease airflow through your cat's lungs. They do that by relaxing the muscle fibers within the cat's lung channels (bronchioles). So they 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 – is probably most commonly 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, they administer the injections at home when needed.
The use of bronchodilators on a day-to-day basis in asthmatic cats is controversial. Some feel it might be a helpful adjunct to daily corticosteroid inhalation while 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 literature 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 cramps and even seizures when the dose is excessive for the particular animal). (rptref1, ref2)
In April of 2016, the FDA approved a combination medication similar to albuterol: formoterol, combined with glycopyrrolate, a medication that dries up excess lung secretions. It is called Bevespi Aerosphere. It too might eventually come to have a place in asthma crisis control - but it is too soon for me to know.
Some might be tempted to use nebulizers on 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. (ref)
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. Also, lungs that contain mucus and the debris of inflammation are great sites for bacterial growth. 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 see if an antibiotic, such as doxycycline, or perhaps a fluoroquinolone antibiotic might improve the pet's breathing function. It is also why boarding a known asthmatic cat during you vacations or taking them to groomers is not a good idea.
A September, 2017 article by an Oklahoma State University veterinary professor points out that neither cyproheptadine, cetirizine,nebulized lidocaine or maropitant are effective in treating asthma in cats. (ref1, ref2)
Some veterinarians believe that a 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 as an appetite stimulant. I do not recommend that it be given to cats with any indication of liver problems. (ref) Although cyproheptadine is an antihistamine, it has many other effects. Many of those effects influence mood. (ref) Other antihistamines have not proved very helpful for asthmatic cats.
A compound was isolated from rat saliva that is often referred to as feG (aka tripeptid FEG [Phe-Glu-Gly] or feG-COOH). It was found to have anti-inflammatory effects similar to corticosteroids and it seems to lessen the inflammatory cascade seen in a number of allergies. (ref) without many of the side effects of corticosteroids. For a while, it was mentioned as a possible feline asthma medication option. A few studies suggested that it might be beneficial in halting a severe asthmatic attack in cats, but its long term use did not appear helpful. (ref)
In 2014, a new drug, omalizumab (Xolair®) was approved as a treatment for human asthma. It is ‘humanized” antibody that blocks the ability of IgE antibodies to produce an allergic response in people. That is, it is an antibody against an antibody. (ref) These “synthetic” antibodies can themselves cause the body to generate antibodies to neutralize them if they are not designed to be very similar to human tissue (be histocompatable). So Xolair® developed in mouse tissue (ref) was “humanized” . (ref) I assume that these “humanized” antibodies would not be effective in your cat because your cat would recognize them as foreign - but I do not know anyone who has checked this out.
Cats can be tough customers to pill. Some are impossible to pill. So the temptation is always there to have some pharmacy prepare cat medications in a form that can be smeared on the cat's skin (usually the inner surface of the ear). However, no one really knows how much of those custom-prepared medications actually get absorbed – perhaps considerably less than the intended dose, perhaps even more than the intended dose. Only blood level assays – if one can find folks to run them – might determine that. If you resort to using these custom-made products in asthmatic cats, keep that in mind.
I only bring this up because theoretically, if one could cure specific allergies that your cat might have, one might cure asthma through desensitization shots. However, I do not know of a case where it was done successfully in cats.
The first problem is that blood-based allergy screening is notoriously inaccurate. Intradermal skin tests give more reliable results. Veterinarians who are not certified dermatologists are rarely trained to do intradermal skin tests. So they just send your cat's blood sample off to some central lab. (ref)
The second problem is that cats with asthma are probably hyperresonders - prone to be allergic to many things - and even the more accurate intradermal allergy testing procedures are likely to miss at least a few of them. These cats are also the most likely to become allergic to new things as time goes by. But the Cochrane Collaboration that I highly respect has found that desensitization has helped human asthma sufferers (ref) so you might consider it as an option for your cat if other treatments are not working.
Perhaps, in a few cases, lifestyle changes for your cat could avoid the allergens that skin testing might identify even if the cat could not be desensitized to all of them. When test antigens are injected into the skin of your cat to see if they induce an allergic response, one must be very cautious in the amount of those test products that are given because too much might cause an asthma attack.
Consumption of omega-3 polyunsaturated fatty acids (PUFAs) are thought to reduce inflammation throughout the body. (ref) They appear to be effective in reducing the severity of asthma attacks in humans. (ref) So it might be a wise choice to include a high quality krill or coldwater fish oil supplement sold for human consumption in your asthmatic cat’s diet (my preference is for you to give krill oil).
Cyclosporine (marketed for pets as Atopica®) is an alternative option to corticosteroids when veterinarians wants to reduce the production of the antibodies that produce asthma (IgE). But just like corticosteroids, in doing so, one "turns down the volume" of many other facets of your cat's immune system - things like protection against infection and tumors. (ref) Veterinarians and their pet-owning clients might resort to giving cyclosporine if the pet’s response to corticosteroid therapy was insufficient or if any of the side effects of corticosteroids were too severe in a particular pet – say a cat that already had a tendency to obesity, diabetes or heart disease. Cyclosporine can be quite effective in reducing asthma attacks; but it potential for side effects can also be quite substantial - particularly regarding the liver. (ref) Pets on cyclosporine can also have difficulties producing antibodies to protect themselves against a variety of infections. (ref1, ref2) Most cats that receive cyclosporine are given it to deal with skin allergies, but some vets use it in asthmatic cats as well. You can read more about cyclosporine use in cats here , or be content to read the information included with the product packaging here.
I do not believe a cat can be cured of asthma - at least not in 2016. In fact, I would avoid any products or professionals that would offer you that false hope. As I mentioned, if one could identify all the things that irritate your cat’s lungs and avoid them, the number of attacks the cat experiences should drop significantly or cease. But the underlying problem is not in your cat’s lungs. It is a body-wide immune system phenomenon and we do not yet have a method to re-program an immune system once it has made its decisions as to what will unleash its inflammatory IgE antibodies.
But medical knowledge and medical options are advancing in leaps and bounds. More monoclonal antibody medications were approved in 2015 than ever before. (ref) 2016 looks like it will produce a bumper crop as well. Some of these mAbs are already being used in people to block IgE - the type of antibody involved in asthma. (ref) But these are “humanized” medications and I do not believe that there would be a large enough market to develop a product like that that was adapted for your cat (but I would be delighted to be wrong about that).
Medical research has also just passed through the front gate of gene repair with the CRISPR cas9 gene editing tool. (ref) The Broad Institute (rhymes with road) that refined the CRISPR cas9 gene editing technique is also interested in cats. They published the entire cat genome in 2007. (ref) But as with monoclonal drugs, there just aren't enough resources in the veterinary community to expect that to be an option for your cat any time soon.
In sudden asthma attacks, your cat is breathing abnormally because it is not obtaining enough oxygen. It needs that oxygen fast. The two fastest ways to provide it are by providing supplemental oxygen and expanding the diameter of its airways.
Bottled oxygen or an oxygen generator can provide the first and veterinarians have medications that expand the airway passages. They are called bronchodilators. Most belong to a group of medications impressively called β2-Receptor Agonists. These drugs relax the muscle fibers (smooth muscle) that are present in the walls of these tiny air channels. Their effect is dramatic – but they can actually make the problem worse if given for too long or too frequently. But bronchodilators can be lifesavers during an asthmatic crisis. The effect of these bronchodilators is not confined to the cat’s lungs. So cats with other health issues (eg heart disease, epileptic problems, or high blood pressure) have to be even more carefully monitored.
Terbutaline (Brethine®) is one of this bronchodialator class of medications that veterinarians often utilize for cats in respiratory crisis. It can be given to your cat orally or by injection. Another is albuterol (aka Salbutamol, = Proventil®, Ventolin®). Albuterol can be given as a inhalant, as it is in humans for which it was designed. Its effect is more rapid than terbutaline.
Theophylline is not a β2-Receptor Agonist. It belongs in a group of medications called methylxanthines. These compounds also enlarge air passages within the cat's lungs. Vets have gotten away from using theophylline because it is not as effective as terbutaline or albuterol and many feel that it has the potential to cause more adverse side effects than the first two medications. Aminophylline, which is less potent and shorter-acting than theophylline, has the same drawbacks. Both are oral preparations – although they are effective in suppository form as well. Theophylline and aminophylline should not be given at the same time enrofloxacin antibiotic (Batryl and probably other antibiotics that end in -foxacin), ketamine anesthetic or β2-Receptor Agonists are being given.
The vast majority of cat owners and veterinarians do not modify their basic treatment plan frequently once an effective corticosteroid plan has been determined for an asthmatic cat. - One that keeps its everyday respiratory distress to a minimum and the frequency of attacks minimal. After six months or so on a fixed medication dose, one often attempts to give those medications at less frequent intervals and observes if the cat remains stable. The main difficulty in judging the effectiveness of a treatment plan is that the signs of the disease often wax and wane on their own. Sometimes it is seasonal, sometimes cats get better – or worse – for no apparent reason. So one can never be 100% certain that they are better because of the medication dose they are currently on – at least not until considerable time on that dose has passed. But as with all chronic diseases, over extended periods of time, drug doses and lifestyle management need to be revisited now and then.
If your veterinarian began with an oral corticosteroid, such as prednisolone, it might be prudent to see if an inhaled corticosteroid like fluticasone propionate (Flovent©) will keep it stable instead. That is because inhaled corticosteroids are less likely to be absorbed into your cat's blood stream in the quantity that oral or injectable corticosteroids are. That should help minimize the long term side effects of corticosteroid treatment – things like obesity, pancreatitis or diabetes. Remember that inhaled corticosteroids – unlike oral or injectable steroids - take up to 2 weeks to show their full usefulness. So the switch needs to be gradual.
A yearly blood chemistry panel and CBC are wise for cats receiving asthma medications on a day-to-day basis. Blood chemistries and CBCs are also advisable any time there are indications of declining health or a significant weight change.
A scale to weigh your cat and a weight diary may pick up problems even sooner than sophisticated tests or visits to your vet. Appetite is closely linked to your cat’s general health and weight creep-up (which you can manage by restricting calories [ref1, ref2] ) is a common side effect of steroids and some asthmtic cat's avoidance of exercise. Unintended weight loss is of concern as well.
I mentioned earlier that corticosteroids and bronchodilators alleviate the symptoms of asthma but they do not cure the disease. The IgE antibodies and mast cells are still there – they are just suppressed. So a low-level chronic inflammation is probably still present in your cat’s lungs. Chronic inflammation eventually leads to irreversible tissue changes. Some find this a reason to suggest that one never discontinue medications – despite how symptom-free your cat appears to be. There are sophisticated tests (the BWBP test and BALF cytology) that yield information as to what is occurring deep within your cat’s lungs. I do not suggest them in most feline asthma cases because I am uncertain that they yield any information that is helpful in establishing or modifying your cat’s treatment plan. But you can read about those tests – and other unproven medication options veterinarians have contemplated in some of the links I have added to this article.
Although easier said than done, try to remove as many triggers as possible from your cat’s environment. Remember that it is unusual for one single item to be responsible for all of the cat’s symptoms, but asthma triggers are usually fine dust in the air and the debris they carry. 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.
Many of the remodeling and constricting lung changes we see in asthmatic cats – the ones that persist between sudden attacks – are similar or identical to the changes we sometimes see in cats that do not have these sudden asthma attacks but who are still sensitive to debris and dusts that are carried in the air. Both cats have long standing chronic bronchitis. A similar situation occurs in humans. In people, chronic bronchitis is often the result of smoking cigarettes. When these cats do have symptoms, it is usually a chronic cough the owners describe to us. The history you provide to your veterinarian as to occasional asthmatic attacks or the lack of them is really the only thing that points to asthma vs chronic bronchitis as the diagnosis. To confirm one or the other, veterinarians rely heavily on identifying the major inflammatory cell types in the material occluding the cats air passages in telling one from the other. That requires the complex BALF test I mentioned earlier. (reptref)
If the cells brought up with the fluid have a high prevalence of eosinophils, the problem is likely to be asthma. But if eosinophils are scarce and neutrophils predominate in the fluid, it is more likely to be a case of chronic bronchitis. Even then, the BALF test is prone to error. But luckily, the same medications tend to help with either condition