Signs

• The first sign of a developing allergy is often itchy skin, either generalized or in the form of hot spots. The dog may lick its paws or abdomen excessively. There may be wheezing or discharge around the nose and eyes. Less frequently, the dog might suffer from vomiting or diarrhea. The symptoms indicate that the dog's immune system is overreacting to exposure to the allergen.
  
  

Fleas

• Fleas often cause allergic reactions in dogs. It is not the flea itself but proteins in its saliva that cause the problem, and this can happen without a major infestation. A single flea bite can cause a reaction. The dog may scratch or chew itself so severely that large amounts of hair are lost, leaving sores or scabs from which secondary infection can occur.
  
  

Inhalant

• Tree and grass pollens, molds and yeasts in the environment can cause allergies in dogs, as can the humble dust mite inside the home. These minute creatures live in all houses, particularly in carpets and beds, and feed on skin scales that fall from both people and animals. Inhalant allergies can be seasonal or year-round, depending upon the allergens involved. The symptoms are usually a generalized itching and irritation of the skin.
  
  

Food

• Although true food allergy accounts for only about 10 percent of allergy problems, it can appear more prevalent. Many dogs occasionally have problems with a particular food ingredient. This may lead to digestive upset, but is easily treated by a change of diet. A true allergy to a food ingredient will commonly cause symptoms such as excessive chewing or scratching. Usual suspects include beef, wheat, soy and dairy products, but many other common ingredients have the potential to become allergens.
  
  

Treatment

• Treatment depends upon the cause of the allergy. If a food ingredient is involved then a veterinarian may suggest an elimination diet. This will reveal the allergens within the current diet and aid in the choice of a suitable replacement. For a flea allergy the most important treatment is a flea eradication program. Where this proves difficult a veterinarian may prescribe antihistamines. A similar approach is taken for house dust mite allergy, where access to problem areas such as bedrooms should be minimized.
  Essential fatty acids, steroids and hypo-sensitizing vaccines have all proved helpful in reducing the symptoms associated with allergies in dogs.