by Dr. Seth
Fleas are among the most common external parasites affecting our furry friends. With over 2,000 species worldwide, the most prevalent one impacting dogs and cats is the cat flea, Ctenocephalides felis. Despite their tiny size, fleas can cause significant problems, ranging from mild discomfort to serious disease.
The most obvious symptoms of flea infestations include scratching, biting, chewing, and excessive grooming. However, the absence of these signs does not necessarily mean a pet is flea-free. Flea Allergy Dermatitis (FAD) is a common condition in both dogs and cats, triggered by an allergic reaction to flea saliva. For sensitive pets, even a single flea bite can cause intense itching and inflammation.
Fleas do more than just cause itching—they can transmit several diseases and parasites. They are vectors for bacteria such as Bartonella (the cause of cat scratch disease in humans), Rickettsia species, Leishmania, and Yersinia pestis (although the cat flea is a poor vector for this bacterium, which causes bubonic plague). Fleas also serve as the intermediate host for the tapeworm Dipylidium caninum, which can infect pets and, occasionally, humans—especially children. In severe infestations, particularly in young or debilitated animals, flea-induced anemia can become life-threatening due to blood loss.
Detecting fleas can be simple in some cases, but challenging in others. A flea comb can help identify adult fleas or flea dirt (flea feces). Black specks on the skin that turn reddish-brown when moistened usually indicate flea dirt. However, a lack of visible fleas doesn’t rule out infestation—especially in cats, which often groom fleas away before we can spot them.
When fleas are suspected, initiating veterinary-approved flea prevention is often the best course of action. Thankfully, modern flea control has advanced significantly. Topical treatments, oral medications, and flea collars offer effective prevention and treatment. Year-round flea prevention is recommended—even in colder months—as fleas can survive indoors and on rabbits and mice in our yards. It’s important to treat all pets in the household to prevent reinfestation.
Environmental control is also essential. Since most of the flea life cycle occurs off the pet, the fleas we see are just the tip of the iceberg. Regular vacuuming, washing pet bedding, and treating indoor and outdoor environments may be necessary in severe cases.
As summer approaches and flea populations rise, don’t forget your pet’s flea prevention—it’s much easier to prevent an infestation than to treat one.
This article was originally published in the June 2025 issue of Appleton Monthly Magazine.