Environmental Factors

• Allergens that produce skin allergies in dogs are found in bedding, carpeting and other soft surfaces in the home. Outdoors, a dog may come into contact with potential allergens from grass, lakes, ponds, streams and swimming pools. Even exposure to rainwater can cause skin allergies in some dogs.
  
  

Food Sensitivities

• Foods that commonly produce skin allergies include corn, wheat, Brewer's yeast, meat by-products and artificial flavors, colors and preservatives.
  
  

Infectious Diseases

• A fungal, yeast or bacterial infection can easily produce canine skin allergies. Infectious diseases, such as ringworm, warrant immediate medical attention from a veterinarian.
  
  

Parasitic Infestations

• Fleas are a leading cause of skin allergies with scabs on a dog. Ticks and mites cause similar problems.
  
  

Neurogenic Conditions

• Skin allergies in dogs that are neurogenic in origin, meaning self-inflicted, sometimes occur after suffering an injury or other trauma. This condition is characterized by constant licking of the area, followed by the development of rash, hair loss and scabs.