Scratching The Surface of Skin Allergies
By Dr. Dieter Kohlmaier, DVM
(This article was originally published in the September/October 2011 Issue of Pets Magazine and is reproduced here with the permission of the publisher.)
Skin allergy conditions equally affect males and females, regardless of age or breed. Since there are many causes of skin allergies, I have divided them into four main categories.
Food allergies are very common in dogs - the majority exhibit initial symptoms before the age of three. Dietary protein is the most common source of this allergy, which affects the face, ears, feet, groin, and armpit regions. A chronic ear infection, however, is often the only sign. Cats can also experience food allergies (though less commonly than dogs), which usually presents as skin lesions and itching around the face, neck and ears. The typical way to diagnose and treat a suspected food allergy is to provide a diet that contains protein to which your pet has not been exposed for a minimum of eight weeks, ensuring that no other foods are given. Individual protein can be removed, then reintroduced to determine whether or not they are the cause of the allergy.
Contact allergies are not common in pets, but when they do occur reactions are typically found only at the sites of contact with the allergen, or areas where the hair coat is sparse. Possible allergens include plants, plastic food dishes, wool, carpet deodorizers and cleaning chemicals. The diagnosis of a contact allergy is not easily made, but by eliminating potential sources and identifying any reduction in clinical signs of allergy, we can usually identify the culprit.
Insect Bite Allergies
Insect bites, particularly from fleas, can also cause allergic reactions in pets. Flea allergy dermatitis can occur in dogs and cats that are hypersensitive to the saliva in a fleas bite. The ensuing reaction produces raised bumps or scabs and hair loss along the backbone to the base of the tail. Mosquito bites can also leave raised red bumps, as with humans. Biting flies will target the tips of a dogís or catís ear, and cause thick, dark, scabby lesions that will easily bleed, as well as distinctive head shaking. Control consists of housing the pet indoors and applying insecticides to the ears as a deterrent.
Allergic Inhalant Skin Disease
The most common form of allergy in pets involves allergic reactions to inhaled substances by animals that are genetically predisposed to them. This type of allergy is known as atopic dermatitis, or simply atopy. Atopy affects 10% to 15% of the dog population, and usually appears within the first three years of life. Environmental allergens, house dust mites, pollens (tree grass and weed) and mould spores are mostly to blame. While pets may only experience seasonal itchiness (e.g., with pollen allergy), most often more than one allergic "trigger" exists, and susceptible pets experiences discomfort year round. Lesions can appear in many locations of the body, including the face, ears, ventral neck, chest and abdomen, as well as the lower parts of the limbs (especially between the toes). Pets will often suffer from chronic itchiness, and many will experience secondary chronic skin and ear infections. There are many treatments available for atopy, ranging from essential fatty acids and antihistamines to corticosteroids and newer medications, such as cyclosporine. Some pets get relief through desensitization injections, as long as specific allergens can be determined by skin or blood testing.
Allergic skin disease can be frustrating for the pets, and also for their keepers. Veterinarians can sometimes find it a challenge to obtain a definitive diagnosis, but with patience and perseverance most cases can be "solved". There is no cure for allergies, and lifetime avoidance measures and symptom treatment might be necessary to ensure the allergic pet maintains a high quality of life. Consult your veterinarian to get relief for your pets itchy skin.