Summer is upon us, and that means more pets are arriving to the animal hospital with allergies and corresponding clinical signs.  Oftentimes, their itchy skin and hair loss is related to fleas. These small parasites are frequently found outdoors and can jump on a dog while he or she is sunbathing, taking a walk, or playing ball. An allergic reaction to the saliva can occur in sensitive dogs when a flea bites, leading to intense itching, hair loss, and inflamed skin. This can be incredibly uncomfortable!

If your dog is experiencing itchy skin or losing hair, it is best to see a veterinarian for a thorough physical exam. A flea comb can be used to identify any live fleas or flea dirt (feces of fleas). The most common distribution of hair loss and inflamed skin secondary to flea allergies is on the rear end near the tail base and down the hind legs.  Absence of fleas or flea dirt does not necessarily rule out flea allergy dermatitis. When a dog goes outside, a flea can still jump on, bite, and trigger a reaction.

Flea prevention is essential year-round to prevent infestations and these secondary signs. Once present, fleas can be difficult to treat due to their extended life cycle. Schedule a visit with your pet’s veterinarian if you have any questions or concerns about fleas or preventative options.

Common Causes of Skin Allergies in Pets

Below are three of the most common causes of allergic skin disease in pets.


The most common pet allergy is caused by fleas. Fleas are parasites that feed on a pet, and their saliva can trigger an allergic reaction, resulting in hair loss, redness, and intense itching. Hairless regions near the base of the tail are commonly seen in dogs and cats. Cats will sometimes experience hair loss around their chins as well. If your veterinarian suspects a flea allergy, he or she will check for evidence of live fleas and flea dirt. Your veterinarian will be able to make recommendations as far as an effective topical or oral flea preventative product as well as ways to rid the environment of fleas and their larvae. It can unfortunately take several months to resolve a flea infestation.


Another allergy we commonly see in pets is environmental. This is medically referred to as atopic dermatitis. Something in the environment, whether it is grass, pollen, dust, etc, causes a pet to become itchy after multiple exposures. Hairless regions or redness on the paws and inguinal regions are most common since these are the areas allergens touch when a pet is walking or laying down. These allergies can be a little more difficult to conquer. If further testing beyond a primary care veterinarian is necessary, a dermatologist can perform additional allergen testing and make treatment recommendations.


Some pets also develop food allergies after being on the same diet over time. These allergies develop as the body becomes sensitized from repeat exposure to a certain ingredient within the food. Typically the allergic component is the protein. Resolving a food allergy involves strict diet trials over several months. Recurrent ear infections can also be suggestive of possible underlying food allergies.

As always, if you notice changes to your pet’s skin or coat, it is best to schedule a veterinary visit to get to the bottom of it!