Itchy Dog: Fleas vs Flea Allergies Wellnergy Pets

Itchy Dog: Fleas vs Flea Allergies

It’s springtime and your pet is starting to itch again. Maybe it’s because it’s time for grooming, maybe it’s because our skin is starting to get dry, or maybe it’s fleas. While fleas may cause some level of itch and irritation in a pet, when the itching is excessive to the point of redness, sores, or scabs, allergies or infections may be a secret underlying secondary perpetrator. An allergy to the saliva of the flea can cause excessive itching and inflammation beyond the mild irritation from flea bites seen in pets without flea allergies.

First things first, what are fleas?

Fleas are small, dark brown, jumping insects that feed on blood. They are prevalent throughout the US, and they are the most common external parasite we see in our patients. When we do see them on our pets, however, understand that the fleas you may notice on your pet are only a small portion of the flea population in your home. By the time you spot them, your pet and home are likely already infested.

What is a flea allergy or flea bite dermatitis?

To review our allergy article (link here), an allergy is an abnormal, excessive response to an otherwise non-harmful substance, that may take years to develop. In the case of a flea bite allergy, this substance is a protein in the flea’s saliva, which can pass through your pet’s skin and cause an allergic reaction in your pet’s body. Just as one bee sting can cause a severe allergic reaction in some individuals, rather than just local pain and inflammation, the bite of just one flea may be enough to cause a full-blown allergic reaction in some pets. Therefore, even intermittent flea exposure can lead to a flea allergy response and thus an itchy dog.

What are signs of a flea allergy?

Flea allergies often cause a skin condition called Flea Bite Dermatitis, and can range from superficial, with mild itching, to deep, with severe and intensely painful inflammation and infection of the skin. This condition can cause “hot spots”, which are usually circular, red, oozing, painful skin sores that commonly become infected. In addition, also look for signs of:

  • Intense scratching, biting, and chewing at the skin
  • Excessive grooming/licking
  • Hair thinning or loss (especially at the base of the tail, middle of the back, and on the abdomen).
  • Extensive skin damage, sores, or scabs
  • Crusts, abrasions, pimple-like bumps
  • Presence of Fleas, and flea dirt in various part of the body

How are flea allergies diagnosed and treated?

Because many different skin allergies and infections may look similar, diagnostic tests to rule out different diseases requiring different treatments are important in the diagnosis and treatment of flea allergies, along with looking at clinical signs. However, if suspected, there are many medications your veterinarian my prescribe to help soothe the scratching and treat secondary infections, such as oral antibiotics and anti-inflammatories, topical antibiotics and anti-inflammatories, and special shampoos. Additional skin and coat supportive diets and supplements may be recommended for long term care at home to help as well, such as Wellnergy Pets collection of skin and coat supplements to help with your pet's skin inflammation, itch, and irritation:

Aggressive and long-term treatment of fleas themselves is also an essential part of treatment for flea allergies. Treatment needs to be consistent, otherwise, flea allergy-related skin issues tend to recur for life, as just one flea bite for some pets can start an allergic response. In addition to continuous flea medication use, treatment of the environment is important to prevent your pet from being re-infested or re-exposed.


I hope this article helps to clear up and confusion between the difference in mild flea related itching and the severe itching and skin disorders that correlate with flea allergies. If you suspect your pet is dealing with fleas or flea allergies, please visit your local veterinarian. As always, feel free to reach out to our team on Facebook, Instagram, email, or in the comments section below if you have any other questions.


About the Author:

Dr. Zonram Liao D.V.M.Dr. Zonram Liao D.V.M. is a Southern California native, and earned his undergraduate degree from University of California, San Diego before obtaining his veterinary degree from Ross University School of Veterinary Medicine. He is not only a firm believer in the use of supportive care supplements to improve the health and happiness of his patients, but also is a strong advocate of the benefits of preventive care medicine for his patients as well. During his free time, Dr. Liao enjoys spending his time outdoors fishing and hiking, playing basketball, watching movies, cooking, traveling, and trying new foods.

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1 comment

WOW that was so informative!

Elton J.

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