What are allergies and how do they affect cats?
One of the most common conditions affecting cats is allergy. An allergy occurs when the cat’s immune system “overreacts” to foreign substances called allergens or antigens. Those overreactions are manifested in one of three ways. The most common manifestation is itching of the skin, either localized in one area or a generalized reaction all over the cat’s body. Another manifestation involves the respiratory system and may result in coughing, sneezing, and wheezing. Sometimes, there may be an associated nasal or ocular (eye) discharge. The third manifestation involves the digestive system, resulting in vomiting, flatulence or diarrhea.
How many types of allergies are there and how are they each treated?
There are four known types of allergies in the cat: contact, flea, food, and inhalant. Each has common clinical signs and unique characteristics.
Contact allergies are the least common of the four types of allergies in cats. They result in a local reaction on the skin. Examples of contact allergy include reactions to flea collars or to types of bedding, such as wool. If the cat is allergic to such substances, there will be skin irritation and itching at the points of contact. Removal of the contact irritant solves the problem. However, identifying the allergen can be challenging in many cases.
The area most commonly involved is over the rump or base of the tail. In addition, the cat may have numerous, small scabs around the head and neck. These scabs are often referred to as miliary lesions, a term which was coined because the scabs look like millet seeds.
The most important treatment for flea allergy is to eliminate all fleas.
Inhalant allergy (or atopy) is common in cats. Cats may be allergic to all of the same inhaled allergens that affect us. These include tree pollens (cedar, ash, oak, etc.), grass pollens (especially Bermuda), weed pollens (ragweed, etc.), molds, mildew, and the house dust mite. Many of these allergies occur seasonally, such as ragweed, cedar, and grass pollens.
Most cats that have an inhalant allergy are allergic to several allergens. If the number of allergens is small and they seasonal, itching may last for just a few weeks at a time during one or two periods of the year. If the number of allergens is large or they are present year-round, the cat may itch constantly.
Treatment depends largely on the length of the cat’s allergy season. It involves one of two approaches.
Steroids will dramatically block the allergic reaction in most cases. These may be given topically or orally depending on the circumstances. The side-effects of steroids are much less common in cats than in people. If steroids are appropriate for your cat, you will be instructed in their proper use.
The second approach to inhalant allergy treatment is desensitization with specific antigen injections or “allergy shots”. On average, approximately half of the cat’s receiving desensitization therapy will experience a significant decrease in their clinical signs. This approach is not used with food allergy.
Although desensitization is the ideal way to treat inhalant allergy, it does have some drawbacks and may not be the best choice in certain circumstances.
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.
The allergy most frequently develops in response to the protein component of the food; for example; fish, beef, dairy, or chicken. Food allergy may produce any of the clinical signs previously discussed, including itching, digestive disorders, and respiratory distress. Food allergy testing is recommended when the clinical signs have been present for several months, when the cat has 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 at least eight weeks for all other food products to get out of the system, the cat must eat the special diet exclusively for a minimum of eight to twelve weeks. If a positive response occurs, you will be instructed on how to proceed. If the diet is not fed exclusively, it will not be a meaningful test. We cannot overemphasize this. NO table food, treats or vitamins can be given during the testing period.
Because cats that are being tested for inhalant allergy generally itch year round, a food allergy dietary test can be performed while the inhalant test and antigen preparation are occurring.
Allergies are a frustrating disease that is often never cured, just, hopefully, controlled. Please call us with your questions and concerns.