An itchy cat can keep you up at night. Sadly, cat's with allergies can often do this until they are missing hair and covered with scabs.
Allergies are complicated and fortunately, our doctors have over a century of combined experience diagnosing and treating them.
The earlier you notice the symptoms of allergy, the easier it tends to be to treat them.
Allergies in Cats
Author: Ernest Ward, DVM
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. Allergens and antigens are simply foreign proteins that the body's immune system tries to remove. These overreactions are manifested in one of three ways:
How many types of allergies are there?
There are four common types of allergies in the cat: contact, flea, food, and inhalant. Each has common clinical signs and unique characteristics.
What is Contact Allergy and how is it treated?
Contact allergies are the least common of the four types of allergies in cats.
They result in a local reaction on the skin from contact with an offensive (allergic) substance. Examples of contact allergy include reactions to shampoos, 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.
What is Flea Allergy and how is it treated?
Flea allergy is the most common allergy in cats.
A normal cat experiences only minor skin irritation at the site of the bite in response to fleabites. The flea allergic cat, on the other hand, has a severe, itch-producing reaction when the flea's saliva is deposited in the skin. Just one bite causes such intense itching that the cat may severely scratch or chew itself, leading to the removal of large amounts of hair. There will often be open sores or scabs on the skin, resulting in a secondary bacterial skin infection (pyoderma). 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 dermatitis, a term that was coined because the scabs look like millet seeds.
The most important treatment for flea allergy is to eliminate all fleas. Therefore, strict flea control is the cornerstone of successful treatment. Unfortunately, this may be challenging in warm and humid climates, where a new population of fleas can hatch out every fourteen to twenty-one days. Topically applied monthly flea products may kill fleas before they have a chance to bite your cat. When strict flea control is not possible, injections of corticosteroids, also referred to as "cortisone" or "steroid shots", can be used to block the allergic reaction and give immediate relief. This is often a necessary part of with the initial treatment flea allergies. Fortunately, cats appear relatively more resistant to the negative side effects of steroids than other mammalian species. If a secondary bacterial skin infection occurs from the flea allergy dermatitis, appropriate antibiotics must be used, generally for two to four weeks.
What is Inhalant Allergy or Atopy and how is it treated?
Inhalant allergy or atopy is estimated to be the third most common type of allergy in cats. It is sometimes referred to as "seasonal allergy" when related to pollens.
Cats may be allergic to all of the same inhaled allergens that affect humans. These include tree pollens (cedar, ash, oak, etc.), grass pollens (especially Bermuda grass), weed pollens (ragweed, etc.), molds, mildew, and the common house dust mite. Many of these allergies occur seasonally, such as ragweed, cedar, and grass pollens. However, others are with us all the time, such as molds, mildew, and house dust mites. When humans inhale these allergens, we express the allergy as a respiratory problem. Atopy is also sometimes called "hay fever". The cat's primary reaction to atopy is severe, generalized itching.
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:
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.
What is Food Allergy and how is it treated?
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. Food allergies are now estimated to be the second leading cause of allergic dermatitis in cats. The allergy most frequently develops in response to the protein component of the food; for example, beef, pork, chicken, or turkey. Vegetable proteins such as those found in corn or wheat may cause food allergies in some cases. 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 by blood tests (IgE) or by feeding an elimination diet or 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. This means absolutely no treats, other foods, people foods or flavored medications during this period. We cannot overemphasize this. Even accidentally providing a tiny amount of the offending protein can result in invalidating the test.
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.
If you have any questions about your cat's allergies please give us a call. We are here to help.