But I never see fleas!

Many pets suffer from allergies, and it can be a real battle to find the cause. If you have never seen a flea, believing your veterinarians when they suspect flea allergy dermatitis can be difficult. However, flea allergy dermatitis is one of the most common reasons dogs and cats itch. Even in the absence of fleas, these critters could still be responsible for an itchy pet!

Sometimes veterinarians suspect flea allergies due to the presence of flea dirt.  This is flea excrement that looks like small brown-black specks on your pet that can be found by inspection of the skin and coat. Flea dirt gives a reddish tinge when placed on a damp paper towel, differentiating it from other particles. The red tinge is due to the presence of blood, which fleas consume on your pet. Because of this, high flea burdens can lead to anemia, or decreased red blood cells, in your pet as well.

Another reason your veterinarian may suspect flea allergies is due to the distribution of itch and related signs. The figure below from the BMC Veterinary Research Journal by Hansel et al in 2015 depicts the most common sites of flea allergy related itchiness, redness, hair loss, etc.

Additionally, since tapeworms are transmitted by flea consumption, it is reasonable to suspect a flea issue if there is evidence of these intestinal parasites.

Flea allergies are preventable with products, such as Bravecto, that stop fleas from jumping and staying on dogs and cats. Having all of your pets on year round flea prevention (even pets without flea issues!) is key for preventing flea allergies. However, treating fleas and flea allergies may require time, effort, and a multitude of products for your pet and your environment. Some pets may need antibiotics, anti-histamines, anti-itch, and anti-inflammatory medications, as secondary infections are common. Flea eggs can hide easily in carpets and furniture, and can survive in our homes even through the winter months. However, with year round flea preventatives for all of our pets, we can decrease the chances of flea infestations, anemia, tapeworms, and of course, itchy flea allergies!

Work Cited

Flea image from Merck Veterinary Manual website

  1. Hansel et al. “Canine atopic dermatitis: guidelines for diagnosis and allergen identification.”

BMC Veterinary Research (2015) 11:196. DOI 0.1186/s2917-015-0515-5.

Merck Veterinary manual online source, flea allergy dermatitis dog and cat sections.




  1. https://www.merckvetmanual.com/integumentary-system/fleas-and-flea-allergydermatitis/


Flea image from Merck vet manual originally from Dr. Michael W Dryden.


Veterinary partner website “flea control for allergy cases”




Veterinary partner website “flea anemia”




Veterinary partner website “tapeworms”


A. https://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=562