There are a variety of conditions that can make a dog itch or have hair loss, including autoimmune. endocrine, infectious, and parasitic skin diseases. Therefore, it takes some detective work to identify the cause. A veterinarian may be able to diagnose the problem. Alternatively, they may need to refer your dog to a veterinary dermatologist, who is a specialist in treating skin conditions in animals.
If allergies are suspected, the first thing a veterinarian will usually ask is if the pet is on a flea-control product. Flea allergies are quite common and are the easiest to control. There are many options for flea control on dogs and in their environment. Once flea allergies are ruled out, and if the itch is non-seasonal, food allergies are the next thing to be checked. Food allergies are not related to a season, whereas many atopic allergies start out as a seasonal problem.
Dogs that develop atopic allergies typically show symptoms between 1 and 5 years of age, but food allergies can be a problem at any time. They are high on the list of suspected causes when a dog first gets itchy skin at an age of over 5 years, or less than 6 months. When testing for food allergies, the dog is put on an “elimination diet” for at least 10 weeks. This means the dog is fed food that consists of a protein and carbohydrate that the dog has not eaten before, such as venison, duck, and potatoes.
These special foods, which come in packets or cans like normal dog food, may be found in retail stores. Or, the owner may choose to feed the dog a homemade diet of foods based on recommendations from the veterinarian. Should the dog’s itching subside by at least half, the allergen is clearly being caused by one of the foods that make up its regular diet. To confirm this, the dog owner can reintroduce the regular diet to see if the symptoms return.
To pinpoint the specific ingredients that trigger the allergy, the dog owner should add one ingredient at a time from the regular diet into the special diet. This should be done for at least a week until the itching increases, indicating that the last added ingredient is an allergen. Alternatively, the owner may decide to stay with the special food to avoid causing the dog discomfort each time an allergic ingredient is fed. Either way, while the dog is being tested for food allergies, it should not be given treats, table scraps, or rawhide toys that may contain an allergen.
To check a dog for atopic allergies, veterinary dermatologists use an intradermal allergy test, or skin reaction test. The dog is mildly sedated, a small area on the side of the dog is shaved, and small amounts of potential allergens are injected into the skin on the shaved area. If the dog is allergic to one of the injected substances, the skin will become inflamed at the area of the injection.