Wednesday, January 8, 2014

Spotlight: Asthma in Cats

Feline Health Spotlight: Asthma in Cats

Many of us humans who have asthma will get it when we're around cats; I know I do. Luckily, they have better drugs for that these days than when I was a child, so I can live with a limited number of cats. Two seems to be my maximum!

But what about cats? Turns out they can get asthma, too, and an increasing number of them are being diagnosed and treated for it.

Only about 1% of all cats are affected by asthma. Doesn't seem like a lot of them, but if yours is one, that's enough! And asthma diagnoses do seem to be increasing as our environments become increasingly polluted. Cats who develop asthma generally start showing symptoms between the ages of 2 and 8 years but the disease will remain with them for the rest of their lives. Females are slightly more predisposed to it than are males. Purebred Siamese and Himalayan cats also seem to have a higher incidence of asthma than other breeds or plain old alley cats.

How Asthma Affects Cats

Asthma is considered to be an obstructive lung disease because it restricts air flow to the lungs. A cat's lungs operate pretty much the same way as a human's. In a healthy cat, the lungs are two expandable bags that fill most of the chest cavity. Inside these bags are airways (bronchioles) through which air is inhaled and exhaled. There are also tiny sacs (alveolae) that extract life-giving oxygen from that air and pass it into the bloodstream, then extract carbon dioxide from the blood that is then exhaled through the airways. A normal cat breathes 24-30 times per minute while relaxed and sleeping.

Just as in humans, asthma causes the small air passages in a cat's lungs (the bronchioles) to become inflamed. The swelling makes it harder for kitty to breathe. Muscles around the bronchi in the cat's lungs constrict and spasm, worsening the problem. The breathing tubes leading to the lungs (the bronchi) slough off cellular matter that gets in the way of air passing through them to and from the lungs.

The lungs of an asthmatic cat also produce mucus, causing the cat to cough and wheeze. Air will become trapped in the lungs, unable to escape due to the swelling. This further restricts the available lung space for fresh, oxygenated air to enter the cat's lungs. During an acute asthma attack, a cat's normal respiration rate can go up to 40 times per minute. These breaths will also seem more shallow, as the lungs are already filled with old air that can't escape and there isn't as much room for fresh air to enter.

In between attacks, an asthmatic cat may appear perfectly normal, enjoying all the things a normal cat does. But when the thing that triggers the cat's asthma is present, an attack will ensue. Asthmatic cats will have chronic, ongoing inflammation in the lower portions of their lungs all the time. Cats are adept at hiding any symptoms of weakness; it's a survival method going back to their wild days. So you may not notice milder symptoms of asthma in your cat, and your first clue that something is wrong will come during an acute attack.

What Causes Asthma in Cats?

Asthma triggers cause the airways leading to the lungs to become inflamed, as described above. These triggers can be any number of things, many of which are also triggers of human asthma:
  • Poor air quality due to pollution, aerosol sprays, or cigarette smoke
  • Physical exertion
  • Cold, dry air
  • Severe heat
  • Allergens: pollen, mold, cat litter dust, cigarette smoke, fragrances, or some foods
  • Obesity
  • Stress
Why some cats have asthma and others don't in the same conditions is as mysterious as why it happens in people. There's likely a genetic factor that causes the cat to be sensitive to certain allergens. Exposure to those allergens produces a bronchitis condition in the cat. Sometimes it's a combination of factors.

An organism called Bartonella has shown in some studies to trigger a type of chronic respiratory infection in cats that looks a lot like asthma. If this is the cause of your cat's symptoms, a simple test can determine this and appropriate treatment can be administered. Asthma itself is not the result of an infection, but a response of the cat's immune system to certain triggers. This is why, in humans, allergists and immunologists typically treat asthma.

Symptoms of Feline Asthma

Cats who have severe asthma are pitiful to observe. They will be wheezy and coughing, just like with humans. You may at first mistake this coughing for the cat trying to hack up a hairball. But no hairball will emerge.

Asthmatic cats may breathe in a distressed manner, hunching their shoulders and extending their neck in what's called a "praying position" as they gasp for breath. Or he may sit up tall to try and "reach" for breath. You may hear a gurgling sound when the cat breathes and his sides may heave in and out. Kitty may breathe with an open mouth in an attempt to get more air into the lungs. Breaths will be fast and shallow, up to 40 breaths per minute.

The cat's chest may look larger than normal due to excess air trapped inside the lungs. When an asthmatic cat coughs, the discharge is typically foamy and mucousy. The cat may even vomit. You'll likely sense panic in your cat, as he knows something is wrong with him. Not being able to breathe is scary for anybody! An asthmatic cat's lips and gums may even turn blue due to oxygen deprivation (cyanosis). A severe asthma attack can be life-threatening.

You may notice the cat's symptoms are worse at certain times of the year, when allergens to which your cat is sensitive are more prevalent. Lack of oxygen will also cause kitty to be weak and lethargic year-round, not just during the season when allergens are present. Over time, this grows worse. During a severe attack, a vet listening to the cat's lungs with a stethoscope may hear cracking and whistling noises from the constricted airways.

Many of these same symptoms can also be indicative of other feline health issues like hairballs, heartworms, hernia, heart disease, third-stage FIP, respiratory parasites (lungworms), pneumonia, or lung cancer. So if your cat exhibits any of the above symptoms, especially in combination, a trip to the vet is in order. While there's no one medical test that confirms an asthma diagnosis, a combination of diagnostic tests that include X-rays of the lungs, blood tests, and perhaps a tracheal saline wash of some cells can reveal telltale signs of it, as well as rule out these other possible causes of the symptoms. Once a proper diagnosis is made, treatment can begin. The cat's reaction to treatment can also help confirm an asthma diagnosis.

Not all cats with asthma suffer severe symptoms, however. Some may only have mild wheezing and a slight cough. This is usually true in all early stages of asthma. But if left untreated, these mild symptoms can develop over time into a more severe form of asthma. Progression from a mild stage of asthma can escalate to an acute attack within hours or months.

Treatments for Feline Asthma 

If your cat has a severe asthma attack, it's critical that you get kitty to the vet as soon as possible. Your vet may give the cat a shot of epinephrine to counteract the allergic reaction. Do not give your cat any human asthma medications, as they are too strong and could prove fatal. Antihistamines and cough suppressants, even if for a cat, may also make the condition worse, so don't try to self-medicate kitty if an acute asthma attack is in progress. 

A vet will likely also put the cat in an oxygen chamber to help him breathe and relax. The stress of fighting for breath can often exacerbate the asthma attack, so just being in an oxygen-rich environment that's free of pollutants is relaxing to a cat undergoing an asthma attack. Vets can also give a bronchodilator like albuteral or aminophylline to dilate the bronchial tubes through an inhaler mask. One brand name of these is Apo-Salvent®.

Again, just as in humans, there is no "cure" for asthma in cats. But the condition can be managed effectively. Believe it or not, there are home-use inhalers specifically designed for cats! Both bronchodilators and corticosteroids such as terbutaline, fluticasone propionate (Flovent®), and cortisone are often administered this way. One brand name of kitty inhaler is Aerokat. It contains a mask and spacer system, just like the systems used for small children or babies. Terbutaline specifically targets the smooth muscles around the bronchi that tend to constrict during an asthma attack, and can be injected under the cat's skin during an acute attack.

A corticosteroid such as prednisone or prednisolone can also be given in pill form every other day for a couple of weeks to minimize inflammation, then tapering off afterward. Corticosteroids help combat inflammation of the cat's airways, but oral versions affect the entire body, sometimes with side effects that can include diabetes and pancreatitis. For this reason, if a cat will accept an inhaled version, those are preferred because the effects of the drugs are localized to the lungs themselves, avoiding the systemic effects. It may take up to two weeks for the full benefit of inhaled corticosteroid treatment to become apparent. Treatment needs to continue, even when the cat appears to be normal again.

Some vets give asthmatic cats shots of methylprednisolone acetate every 2-4 or 5-7 weeks to help reduce inflammation and keep the airways open. Others may give an antihistamine such as cyproheptadine as a continuing treatment. The causes of your cat's asthma will determine which treatments are tried, along with the cat's response to them.

If your cat is overweight, a loss of weight will help, and an exercise program that gets kitty up and moving around will improve lung function. Start slowly, and gradually increase the cat's activity level. One of the side effects of long-term corticosteroid use is a tendency to put on weight, so be mindful of this if your vet prescribes a continuing treatment of such drugs.

Changes to the cat's environment are also called for. Reducing the cat's exposure to cigarette smoke and other environmental pollutants is extremely beneficial. If you smoke, consider switching to an electronic cigarette, which doesn't produce the toxic fumes that will kill your cat (and you!). Avoid having your cat in the room while your fireplace is burning, as the smoke from it can also trigger an asthma attack.

Find a dust-free type of cat litter and avoid those that have an added fragrance. Don't use any litter additives touted as odor-controlling, for the same reasons. You may even have to use shredded newspaper litter for a while, as you rule out additional asthma triggers. 

Change the filter in your air conditioner/heater monthly. Remove air fresheners from your house and use only unscented or natural cleaners. Don't use a carpet deodorizer, which often is a powder that creates dust and adds a fragrance to the rug that can irritate your cat's asthma. 

In winter, a humidifier can help add moisture to the air, making it easier for your asthmatic kitty to breathe. If your cat's asthma is triggered by severe cold or hot air, keep your cat indoors during those times of year.

Vacuum your carpets frequently, and use a machine with a HEPA filter. Empty it after vacuuming each room to avoid transferring any allergens from one part of your house to another. You may even consider adding a whole-house HEPA filter to your heating/air conditioning system to help your entire family breathe easier.

If your cat shows symptoms of asthma, it's important to get it diagnosed and treated. If left untreated, damage to the lungs will be worse (just like in humans!) and result in pulmonary fibrosis (fibrous tissue filling the lungs) or atelectasis (an inability of the lungs to inflate). The cat will grow progressively weaker until the condition proves fatal. Even with ongoing treatment, sometimes a more severe (acute) attack will happen, just as in humans. As you learn to recognize those symptoms, you'll know how to treat them and your asthmatic cat can enjoy many more happy years with you!

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