Allergy could cause cat's skin irritation

9/22/2007

Dear Dr. Thompson: I have a 6-year-old cat. She has scratched her fur off from her ear, down her neck, to her shoulder. She just had a check-up within the last couple of months. She had a similar spot by her neck. Her vet thought she may have been bitten by something and had an allergic reaction.

ANSWER: First I want to commend you for getting your cat in for her annual check-up. It is the best way for you and your veterinarian to keep your cat healthy and happy for a long time. Skin irritation, called dermatitis, around the ears is a very common trouble spot for cats. If this is a new problem or in a different area, have your veterinarian re-evaluate it. Cats will commonly scratch around their head and face with certain types of allergies. This may be what your veterinarian was alluding to.

These allergies can come from any number of sources, including food, infections, skin mites, or environmental allergies. Even indoor-only cats are susceptible to seasonal allergies from trees, grasses, and weeds. When windows and doors are open, allergens are brought into the house; indoor sources all can trigger these types of reactions.

Cats' fastidious nature exacerbates the problem by grooming pollen and other triggers off the fur. Ear infections can also cause cats to scratch themselves raw around the ears. Your veterinarian will need to check under the microscope to determine what organism is causing the problem. A common misconception is that the only cause of ear infections in cats is ear mites.

Bacteria and yeast can complicate any infection in the ear canal and allergies typically lead to recurring ear trouble. Some species of skin mites can be difficult to detect and lead to long-term dermatitis around the face. I have seen cases in which the cat was miserable from the pain and irritation caused by these mites. Diagnosis is extremely difficult because the mites are nearly impossible to find with the routine diagnostic test called a skin scraping. Often multiple visits are needed to catch the culprit. Trial therapy to eliminate many of these causes may be required. It takes patience and determination by pets, veterinarians, and owners to completely resolve many skin problems.

Dear Dr. Thompson: I have a black lab who will be 2 this fall. He has been biting his paws for the past month and is starting to lose the hair between his toes. I have trimmed his nails so I know they are not bothering him. What would lead him to bite at his feet this way?

ANSWER: Your dog is scratching an itch on his feet the only way he can, by biting, licking, and chewing. In a recurring theme for many pets this fall, allergies are starting to flare. The heavy rains last month led to a resurgence in many pets' allergies. For dogs, feet-licking and chewing are the only symptoms they will show. Dogs' feet come in contact with many environmental allergens. The hair loss you are describing is a secondary infection starting to develop. Your veterinarian needs to evaluate your dog and help determine the best treatment. Early intervention is crucial for any skin infection.

Treatment of the underlying itchiness will help to alleviate some of the problem. Topical sprays, shampoos, and creams are all typical treatments. Oral antibiotics for extended periods may be needed to eliminate secondary bacterial infections.

Your veterinarian may take some diagnostic swabs to make sure you are treating the right problem. I also recommend people with allergic dogs develop the habit of wiping their dog's feet when coming inside. This will help remove some of the topical allergens your dog is coming in contact with. If this problem does not resolve itself with the first couple of hard frosts, you should have your veterinarian evaluate your dog for other sources of allergies.

Questions for Dr. Thompson can be e-mailed to askthevet@theblade.com or mailed to The Blade, Attn. Ask the Vet, 541 North Superior St., Toledo, OH 43660. Dr. Thompson regrets that he cannot answer individual letters.