What are allergies?

The word allergy means 'altered working'. Just like humans, cats can have allergies too. Allergies are a common cause of skin disease in cats.

The purpose of the immune system is to keep infectious microorganisms, such as certain bacteria, viruses, and fungi, out of the body, and to destroy any infectious microorganisms that do invade the body. Allergies are caused by an inappropriate response to a substance which would usually be considered harmless. In an allergic animal, the immune system over reacts to the substance & mounts an immune response against it.

Eosinophilic Granuloma Complex & Miliary Dermatitis have been linked to allergies.

In cats there are four types of allergies; insect (most often caused by fleas, but occasionally mosquito bites can cause an allergic reaction), food, contact & inhalant.

Contact Dermatitis:

This is the least common of the four types of allergy in cats. Contact dermatitis is a result of the cat coming into contact with a substance. The cat's fur acts as a barrier, protecting it from allergy producing compounds.

There are two causes of contact dermatitis; allergic & irritant.

Irritant Contact Dermatitis:

Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, medications, solvents, or other chemicals.

Allergic Contact Dermatitis:

The second most common type of contact dermatitis is caused by exposure to a material to which the person has become hypersensitive or allergic. It arises some hours after contact with the responsible material, and settles down over some days providing the skin is no longer in contact with it. Plants, wool, medications are a common cause of allergic dermatitis in cats.

Symptoms of contact dermatitis:

• Non seasonal itching, especially in areas where there isn't much fur. Typical areas include the chin, ears, toes, underbelly & anus.
• Lesions of any type: redness, rash, papules (pimple-like), vesicles, and blisters
• Skin redness or inflammation
• Thickening of the skin

Diagnosis of contact dermatitis:

Your vet will perform a physical examination & take a history. He/she will want to rule out other causes of dermatitis (such as flea bite hypersensitivity) first.

A skin biopsy may be performed.

A patch test may be performed. This involves applying various substances  to the skin, which is then bandaged over. This is then examined at 24 & 48 hours. A positive reaction will be seen as redness & swelling at a specific site.

A presumptive diagnosis may be made by removing your cat from the environment for a week , if lesions begin to heal, then recur once returned to the environment.

Treatment of contact dermatitis:

Identification & elimination of the substance causing contact dermatitis is the best solution.

Corticosteroids may be prescribed to control the itch.

Antibiotics may be necessary to treat secondary bacterial infections.