Allergies in Cats

One of the most common conditions affecting cats is allergy. In an allergic state, your cat's immune system "overreacts" to foreign substances (allergens or antigens) to which it is exposed.

These overreactions lead to either itching of the skin, respiratory distress such as coughing or sneezing, or digestive problems such as vomiting or diarrhea.

Gabrielle lost hair around her whiskers due to a contact allergy, but is now recovered thanks to excellent care at City Cats.

Types of allergies
There are four known types of allergies in cats: contact, flea, food, and inhalant. Each of these types have both common and unique attributes.

Contact allergies are the least common of the four types of allergies. They result in a local reaction to the skin, such as irritation from flea collars or types of bedding, such as wool. If your cat has a contact allergy, he or she will be itchy and irritated at the point of contact. Removal of the contact irritant solves the problem. The key is to identify the allergen.

Flea allergies are common in cats. A normal cat experiences minor irritation to flea bites, but a flea-allergic cat, on the other hand, has a severe, itch-producing reaction when the flea's saliva is deposited on the skin. Just one bite to an allergic cat can cause such intense itching that the cat may severely scratch or chew itself to the point of removing large amounts of hair. There will often be open sores or scabs on the skin, opening a risk of infection.

The area most commonly involved is over the rump, just in front of the tail. In addition, the cat may have numerous scabs around the head and neck. These scabs are called miliary lesions because the scabs look like millet seeds.

City Cats recommends using glass or ceramic bowls and dishes, as many cats have allergic reactions to plastic and metal. Feline eosinophilic granuloma lesions that are common, and are most frequently seen in cats with allergies to inhalants, foods, or insects. However, bacteria can be a factor. These lesions are often called a "rodent ulcer" that appears around the lips.

Inhalant allergy, or atopy, is the most common allergy in cats. Cats may be allergic to all of the same inhaled allergens that affect humans. These include pollens (cedar, ash, oak, etc.), grass pollens (especially Bermuda), weed pollens (ragweed, etc.), molds, mildew, and house dust mites. Many of these allergies occur seasonally, such as ragweed, cedar, and grass pollens. However, others are with us all the time, such as mold, mildew, and house dust mites. When humans inhale these allergens, we express the allergy as a respiratory problem; it is sometimes called "hay fever." The cat's reaction, however, usually produces severe, generalized itching. In fact, the most common cause of itching in cats is inhalant allergy.

Food allergies can be difficult to diagnose since they result in itching, digestive upset, and respiratory distress. Cats are not likely to be born with food allergies; more commonly, they develop allergies to food products they have eaten for a long time. An allergy to food most frequently develops in response to the protein present in the cat's diet, such as beef, pork, lamb, or poultry. Eliminating the allergen present in your cat's diet resolves the allergy.

Allergy or irritant?

It can be very difficult to distinguish between true allergens and the many local irritants that can cause itching. Some examples of each:

Note that many things can cause itching that are not allergens, and many of the causes mimic each other in appearance. For example, fleas can cause itching in cats that are not allergic to their saliva. Achieving an accurate diagnosis can be time-consuming, but treatment is essential to ensure relief for your cat.

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Diagnosis

City Cats uses the Veterinary Allergy Reference Laboratory (VARL) for diagnosis of allergy tests. VARL serves veterinary clinics all over the United States and in 23 other countries worldwide in the specialized area of serum allergy testing and preparation of individualized prescription allergen vaccines for allergic dogs and cats. VARL is a dedicated laboratory, concentrating on precisely identifying allergens responsible for their patients’ allergies and formulating allergy vaccines to desensitize them to the identified culprit allergens. 

By using VARL's services, City Cats is able to accurately diagnose allergies in your cat without the risk of false positives that are more common in skin testing. We have their brochure available in our clinic, or you can download a PDF from their website.

Treatment

For contact allergies, removal of the contact irritant solves the problem.

The most important treatment for flea allergy is to keep the cat away from all fleas. Strict flea control is the backbone of successful treatment. Unfortunately, this can be difficult in warm and humid climates, where a new population of fleas can hatch every 14-21 days. When strict flea control is not possible, injections of corticosteroids (cortisone or steroids) can be used to block the allergic reaction and give relief. This is often a necessary part of dealing with flea allergies. Fortunately, cats appear relatively more resistant to the side effects of steroid than other species. If a secondary bacterial infection occurs, appropriate antibiotics must be used.

Treatment for inhalant allergies depends largely on the length of the cat's allergy season. Steroids, given orally or by injection depending on the circumstances, will dramatically block the allergic reaction in most cases. City Cats will instruct you as to the proper use of steroids.

Some cats are helped considerably by a hypoallergenic shampoo. Some allergens can be absorbed through the skin; bathing removes surface antigens and provides temporary relief from itching. Bathing may also allow the use of a lower dose of steroids.

A second form of allergy treatment is desensitization with allergy shots. Once the source of an allergy is defined, very small amounts of the antigen are injected weekly, which should allow the immune system to become less reactive to the allergen. If desensitization appears to help the cat, injections will continue for several years. For most cats, a realistic goal is for the severity of itching to be greatly reduced; in some cats it may resolve completely. Steroids generally would not be used with this treatment protocol, except on an intermittent basis. This treatment approach is not used for food allergies.

Although desensitization is an ideal way to treat inhalant allergies, it has some drawbacks, so discussing this approach with the staff at City Cats will help you determine whether this approach will help your cat.

City Cats recommends testing for food allergy when clinical signs have been present for several months, when the cat has had a poor response to steroids, or when a very young cat itches without other apparent causes of allergy. Testing is done with a special hypoallergenic diet. Because it takes 8-12 weeks for food to leave a cat's system completely, your cat must eat the special diet for 8-12 weeks or more. If a positive response occurs, you will discuss continuing treatment and maintenance options with the City Cats staff. City Cats carries special diets prepared for cats with food allergies.

It is important to note: if the hypoallergenic diet is not fed exclusively, the test will not give meaningful results. This means that no table food, treats, or vitamins can be given during the testing process!

Prognosis

You must understand the treatment instructions given to you by City Cats staff in order to ensure that your cat gets relief from his or her allergy symptoms. Because allergies tend to be lifelong problems, treatment may need to continue for the life of your cat. Watch your cat closely for signs that the condition is recurring.

If we recommend feeding your cat a special allergy diet, be aware that any mixing in of other foods can seriously hinder your cat's recovery. Make sure to discuss any dietary changes with City Cats staff before you proceed.

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types of allergies

allergy or irritant?

diagnosis

treatment

prognosis