James R. Speiser, DVM, DABVP, CCRT
June 12, 2015
Cats and dogs can be very hard to live with when they are itchy! Here are some of the most common reasons why they might be scratching:
Allergies
- Inhalant allergies. Dogs are different than people in that pollens and dusts that are inhaled do not bind to cells in the respiratory tract that release histamine and other inflammatory substances, which causes runny nose, sneezing, and stuffiness. Instead, the substances are absorbed and bind to cells in the skin that release histamine and cause dogs to itch. Helpful treatment includes antihistamines, cyclosporine, short courses of steroids, and allergy shots to desensitize pets.
- Contact allergy. Pets can come into contact with substances that will cause a local inflammatory reaction of the skin that is very itchy, similar to poison ivy in people. Having a lot of hair is an advantage to pets, which helps to reduce contact allergies, but they can still occur particularly on the sparsely haired portions of the body where they lay. Topical steroid creams can be effective.
- Food allergy. Proteins in the food can be absorbed and cause itchy pets. A food allergy does not tend to cause upset stomach or diarrhea as much as it can cause itchiness to the skin from a similar mechanism as outlined with inhalant allergies. It’s helpful to test for food allergy and change foods to avoid the protein source that the pet is sensitive to.
Fleas
When fleas bite cats and dogs, the saliva of the flea can bind to proteins in the skin. This combination of proteins will induce an allergic reaction. It does not take an army of fleas to create this effect, no more than it takes a field of poison ivy to give you a poison ivy contact allergy. One leaf will do! Only a few fleas can cause a pet to be very itchy and uncomfortable. Prevention of flea infestation is the mainstay of preventing this allergy, although short courses of antihistamines, steroids, or cyclosporine are effective for severe cases.
Sarcoptic Mange
This is caused by a mite that is received by direct contact with another pet that is infested with the mite called Sarcoptes Scabiei. The mites burrow into the skin particularly around the head, elbows, hocks (the joint bending backward on the hind legs), and other bony prominences, creating an extremely itchy pet! A veterinarian can successfully treat mange. Home remedies are not effective and it can spread to humans in the household.