Cats can have allergies just like humans. Unlike allergies in people, though, a cat suffering from inhaled or ingested allergies will exhibit signs of itching, including scratching, chewing, and biting. One such allergic condition is called feline atopic dermatitis.
What Is Feline Atopic Dermatitis?
Feline atopic dermatitis, sometimes called feline atopy or non-flea, non-food allergic dermatitis, is a common allergic condition seen in cats. In fact, feline atopic dermatitis is the second most commonly-diagnosed allergy in cats, behind flea allergy dermatitis. Feline atopic dermatitis occurs when they inhale an allergen, such as pollen, mold spores, and dust particles, or ingest an allergen, such as beef, chicken, fish, or even dairy. Since allergens can be inhaled or ingested, feline atopic dermatitis may be seasonal or non-seasonal. Seasonal flare ups may be indicative of an inhaled allergen while non-seasonal may be indicative of an ingested allergen, but that's not always the case. Most cats with feline atopic dermatitis are diagnosed in early adulthood as this is when most allergies develop for cats.
Symptoms of Feline Atopic Dermatitis
A cat suffering from feline atopic dermatitis may chew, lick, or scratch all over. Generally, though, the paws, face, ears, axilla (or armpit areas), and the front of the legs are most affected. This is in contrast to the aforementioned flea allergy dermatitis, which causes cats to chew and lick their tail, rump, groin, and thigh area. Of course, it's entirely possible for a cat with feline atopic dermatitis to also suffer from flea allergy dermatitis, so you may see scabby spots and hair loss in both areas.
Unfortunately, as with allergies in people, we don't fully understand why cats get allergies. We can determine what they are allergic to, though, and that can actually help with treatment.
Treatment & Prevention
The first step in treating feline atopic dermatitis is to treat your cat's immediate skin infections. These infections are secondary to their scratching and biting. Your vet will want to take some cytology samples, most often obtained simply by rubbing a piece of scotch tape over a lesion, to determine if a crusty spot has an bacteria, yeast, or both. Bacterial skin infections are then treated with antibiotics while fungal infections are treated with antifungal medications.
To help to immediately relieve your cat's itching, your vet may give an injection of a corticosteroid. Corticosteroids can be very effective in keeping itching and inflammation at bay, but they aren't without their drawbacks. They have side effects with both short-term and long-term usage. They can cause your cat to experience an increase in appetite, thirst, and urination short term, so you may find yourself cleaning out the litter box more regularly and your cat may beg for food more often. Long-term use can lead to organ damage. Your vet can help determine if corticosteroids are appropriate for your cat. They can also help you find the lowest effective dose of corticosteroid for your cat and will want to monitor your cat's bloodwork to check for any changes in organ function.
The most effective long-term treatment of feline atopic dermatitis involves determining what your cat is allergic to. For airborne allergens, your cat's blood can be tested for potential environmental allergies. This involves a simple blood draw from your cat which your vet then sends to a third party lab. Once it is determined what in your environment your cat is allergic to, the lab can create immunotherapy drops that you can give to your cat orally to help build up their immune system.
Some labs can also test your cat's blood for food allergies, but a blood test for food allergens is less reliable than something called a food trial. A food trial involves putting your cat on a prescription, hydrolyzed diet, which helps to determine which protein your cat is allergic to (as cats are more likely to be allergic to proteins versus grains). Hydrolyzed is just a fancy way to say that the protein source is broken down into its individual amino acids, so your cat's immune system won't be able to tell if the protein is poultry, beef, or fish. Your cat will need to be fed this diet exclusively for 8 to 12 weeks as you wait to see if their symptoms resolve. This means no other foods or treats. If your cat's symptoms resolve while they are on the prescription food, their allergies are most likely due to a food allergy. If it's determined that your cat has a food allergy, it is recommended to keep them on the hydrolyzed food for life to prevent allergy flare ups.
Unfortunately, there no current prevention for the development of feline atopic dermatitis. Recognizing the symptoms and keeping up with your cat's flare ups, though, can help keep your cat as comfortable as possible when their allergies are bothering them.