When Your Cat Has Allergies, You Can Ditch the Itch

Many veterinary dermatologists believe a scratching cat has a flea allergy until proven otherwise. But there are other possible causes.

Cats HATE the "cone of shame."

Fur mowers. That’s what we call them: cats that lick and chew their fur away until they’re bald. Usually when their owners aren’t watching. Sneaky little devils. I owned a severely allergic (atopic) cat once. When she was young and adorable, my boys named her Fuzzball. Turned out to be a misnomer. She spent a good part of her life being “Fuzz-no-more.” There actually was some fuzz. Just no fur.

Feline skin disease remains more of a puzzle than canine skin disease. Many of the skin diseases cats suffer from can mimic one another, so a visual inspection of the cat doesn’t always lead to a diagnosis. Diagnostics and determining the reason for the allergy is difficult.

Cats suffer from inhalant, flea and food allergies just like dogs. These allergies create pruritis (itching), sometimes intense. Owners are often unable to give a history of a cat’s scratching because cats prefer to do their grooming, itching and licking when the owners aren’t looking. Likewise, it may be difficult to differentiate normal grooming from excessive grooming until the cat is actually doing harm to itself. This means the allergy or disease has already been going on for some time, making it more difficult to treat.

The lesions caused by a cat’s scratching can vary from mild to severe. A cat may lick until there are large bald spots, or the pruritis can be so severe that the cat scratches, licks and gnaws until she has created deep ulcers, or “plaques.” This is known as eosinophilic skin disease. These lesions can take months to heal. Treatment can be challenging and lifelong.

Once a cat has been diagnosed with allergic skin disease, corticosteroids are often the first line of defense. Steroids can give the cat relief until we can get to the bottom of the allergy, but corticosteroids have may side effects and should be used with caution. We don’t want the treatment to be worse than the disease.

I keep thinking about all those commercials to treat your heartburn, your depression, your restless legs. After the fast-talker runs through the potential risks of the drug including stroke and cancer, how bad is that heartburn again?

Flea Allergy

Many veterinary dermatologists believe a scratching cat is suffering from a flea allergy until proven otherwise. Often I don’t find a flea on an itching cat like I do on a dog. Cats are fastidious groomers; they eat the flea. If it’s a very mild flea infestation but the cat is highly allergic, you may have a balding cat with no evidence of fleas, not even a speck of flea “dirt” (flea excrement).

I try to persuade owners to institute a flea treatment for several months to absolutely rule out fleas as a cause of the allergy. This is true for indoor cats too. Many houses/apartments have fleas unbeknownst to the owner. Visiting animals can bring in fleas. Fleas can invade basements, screened-in porches, etc. Rarely, you — yes, you — can bring in fleas.

Food Allergy

Same as dogs, you need to do a diet trial if you want to test for food allergy. There is no simple test for food allergy. You need to feed a diet that the cat has never been exposed to before. Make sure that the cat eats this diet, and only this diet, for about three months.

This Is Impossible!

Please, Kitty, ditch the itch!

Cats are finicky. They get bored of the same food.

Cats like to go outside. If your cat goes out, it’s impossible to assume he isn’t “dining out.”

“Grain-free” is not a hypo-allergenic diet. You still need to find a novel (new) protein source and keep the diet balanced.

No other ingredients should be in the diet except the novel protein/carb source. If you have a multiple cat household, they ALL have to eat this darned diet!

Just Stop the Itching!

If you can eliminate the offending allergen, like fleas or food, the itching will cease. You may need steroids or other drugs to stop the scratching until the allergen is discovered and eliminated.

Antihistamines, fatty acid supplements, baths and sprays can help somewhat, but a severely allergic cat will usually continue scratching without medications such as steroids, antibiotics or other drugs (like cyclosporine).

Bathing a cat can have some effect. Topicals are difficult to use in cats since the skin lesions are often widespread and the cat can lick, lick, lick all the medicine away! Cats hate Elizabethan collars (cones). As soon as you take off the collar, the cat often attacks the same itchy area with a vengeance.

For an atopic cat, intradermal skin testing and blood testing are available, but they are not as reliable as the canine tests. This testing often requires a visit to a veterinary dermatologist. Talk this over with your veterinarian if your cat’s allergies are moderate to severe.

Threshold Effect

Cats (and dogs) can be allergic to more than one thing, and to varying degrees. If the allergies are mild, the itching might be insignificant. Say your cat’s “itch” number is 100. This means the cat doesn’t start to itch until it reaches 100. Say the cat has a mild flea allergy that rates an itch factor of 60. Then add to it your cat’s allergy to fish, scoring a 50, and buy a case of fisherman’s stew because it’s on sale. This bumps his itch factor to 110, over the threshold.

If not combined, your cat could probably tolerate a few fleas or a can of tuna, because each would be well under that 100 number. But combine them, and he has crossed his threshold. Your cat has entered the itch zone.

The Problem With Steroids

Corticosteroids are life-saving drugs and treat many diseases. But they have side effects and must be used with caution.

Cats are more resilient to the side effects of steroids than humans or dogs, but they are a huge concern nonetheless. Steroids are very beneficial in the beginning of a disease process, but can lose their power as the disease progresses.

There are many forms of injectable and oral steroids, and your veterinarian will make suggestions based on the severity of your cat’s disease.

If used correctly, steroids can greatly control or eradicate pruritis in your cat. Following medical instructions and keeping track of the medication is extremely important.

Mild side effects include increased thirst and appetite, causing increased urination and weight gain. Continual or excessive use of the drug can cause liver and endocrine problems, including diabetes.

Hey Look! Fluffy Is Fluffy Again

Anything you can remember about when/why/how your cat began to itch can be helpful. If your vet prescribed medications, how well these drugs worked and for how long are also very important.

My easiest-going cat, Snoopy, never had a medical problem until he was 8. One summer, I noticed he had periorbital alopecia (hair loss and a little crusting around the eyes). The lesions went away before I got too excited about them. The following summer, the lesions were much worse. I used a topical ophthalmic ointment containing a steroid and gave him one injection. He improved.

His lesions occurred every year at the same time and only on his face. It turned out Snoopy was allergic to mosquitoes (a fairly common cat allergy). Keeping him indoors at the height of mosquito season and particularly at dusk when the bugs are at their worst controlled the problem.

Let’s hope veterinary research will continue to make strides in helping allergic cats with safer and more effective treatment options in the near future. This is by no means an easy disease to treat. In fact, it can make you tear your hair out.

Photos: andersbknudsen (top), Janet 59/Flickr

Dr. Debora Lichtenberg, VMD

View posts by Dr. Debora Lichtenberg, VMD
Dr. Debora Lichtenberg, VMD, is a small animal and exotics veterinarian who has split her time between a veterinary practice in Pelham, Massachusetts, and her studio in New York City. Dr. Lichtenberg is a graduate of the University of Pennsylvania School of Veterinary Medicine with 30 years of experience. Her special interests are soft tissue surgery and oncology.

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