Dog Fleas vs. Cat Fleas. Which Pest is Worse?


Fleas are a common and frustrating problem for both dog and cat owners. At first glance, dog fleas and cat fleas appear nearly identical. However, there are some key differences between fleas that prefer dogs versus those that prefer cats.

Dog fleas and cat fleas are similar in many ways, but cat fleas tend to be more numerous and harder to eliminate. This article will examine the similarities and differences between dog and cat fleas, including their life cycle, effects, and treatment options. It will provide pet owners with a guide to understanding which parasite is plaguing their pet and how to banish fleas from their homes.

What Are Fleas?

Fleas are tiny parasitic insects that feed on blood from host animals. Most fleas are external parasites, meaning they live on the skin of their hosts. A few flea species can live in the fur or feathers of their hosts. Fleas have compressed bodies and are usually less than 1/8 inch (3 mm) long. Their small size allows them to live in the coat, mane, or feathers of their hosts without easily being noticed (Frontline).

Fleas belong to the order Siphonaptera. Some common species that infest pets include the cat flea (Ctenocephalides felis), dog flea (C. canis), human flea (Pulex irritans), oriental rat flea (Xenopsylla cheopis), and northern rat flea (Nosopsyllus fasciatus) (St. Clair Veterinary Hospital).

Life Cycle

The flea life cycle has four stages – egg, larva, pupa, and adult. Female fleas lay eggs on the host which fall off into the environment. According to Understanding the Flea Life Cycle, flea eggs hatch into larvae within 2-12 days in ideal conditions between 70-85°F. The larvae feed on organic debris and mature into pupae within 1-2 weeks. Inside the protective cocoon, the pupa stage can last from 1 week up to 1 year. When ready, the adult flea emerges from the cocoon fully matured and ready to find a host and feed within 2-3 days.

The Orkin website explains that unfed adult fleas can survive 2-3 months without a blood meal. Once the flea finds a host and starts feeding, the adults will start mating and laying eggs within 36-48 hours, thus continuing the rapid flea life cycle. This allows flea populations to grow exponentially if uncontrolled.

Preferred Hosts

Though fleas are not host-specific and will bite a variety of animals, they do tend to prefer and thrive best on certain hosts. Cat fleas (Ctenocephalides felis) prefer cats, but will readily bite dogs and other animals. Dog fleas (Ctenocephalides canis) prefer dogs, but are also not limited just to canine hosts. Even though they have preferences, cat fleas and dog fleas will both bite cats and dogs if given the opportunity.

Cat fleas are the more prevalent type, accounting for up to 95% of flea infestations in the United States. They are well-adapted to feline hosts, with about 70% of adult cat fleas living on cats. However, they will also feed on dogs, humans, and other animals. Often cat fleas end up on dogs due to their close interactions with and proximity to cats in a household. Though they prefer cats, they will thrive on dogs if that is the most accessible host animal.

Dog fleas, while not as common as cat fleas, still account for about 5% of flea infestations in the US. As their name suggests, they prefer dogs and adapt well to canine hosts. Still, if no dogs are present, they are able to utilize other hosts like cats, humans, or other mammals. In multipet households with both cats and dogs, it is likely that both cat fleas and dog fleas will live on and bite both types of animals, even if they have a preference.

In summary, while cat fleas prefer cats and dog fleas prefer dogs, they are not limited just to their preferred host. Both cat and dog fleas are able to bite and live on cats, dogs, and other mammals opportunistically if needed.




Both cat fleas (Ctenocephalides felis) and dog fleas (Ctenocephalides canis) can be found on cats and dogs, but cat fleas are far more common. According to a 2019 study published in Veterinary Parasitology, cat fleas are the most prevalent flea species found on cats and dogs globally (Lawrence et al., 2019). The study notes that the cat flea likely originated in Africa and later spread worldwide alongside the domestication of cats and dogs.

Cat fleas have been able to readily adapt to different environments and hosts, making them the dominant flea species. While dog fleas prefer dogs, cat fleas are less particular and can be found in large numbers on both cats and dogs. This has allowed the cat flea to proliferate. Even in regions with cooler climates that are less hospitable to fleas, the cat flea remains the primary species infesting our furry companions.


Lawrence, A. L., Brown, G. K., Peters, B., Spielman, D. S., Morin-Adeline, V., Šlapeta, J., & Šlapeta, J. (2019). Out-of-Africa, human-mediated dispersal of the common cat flea, Ctenocephalides felis: The hitchhiker’s guide to world domination. Veterinary Parasitology, 274, 108895.

Effects on Pets

Fleas can cause a variety of health issues in pets, ranging from mild to severe. One of the most common is flea allergy dermatitis, which is an allergic reaction to flea saliva. The bites cause intense itching, irritation, and inflammation in pets with this allergy ( The itching and scratching can lead to hair loss, skin wounds, and secondary infections.

Fleas can also cause anemia in pets if the infestation is severe. Their blood-feeding behavior slowly depletes the pet’s red blood cell supply over time. Pets become lethargic and weak as their tissues are deprived of oxygen (PetMD). Young, old, or small pets are most vulnerable to flea anemia.

Ingesting fleas can lead to tapeworm infections in pets. The most common tapeworm species transmitted this way is Dipylidium caninum. The flea larva develops tapeworm eggs inside its body. When the pet swallows an infected flea during grooming, the tapeworm eggs are released and mature in the intestines. Tapeworm segments containing eggs are then passed in the pet’s feces (YourPetandYou).

Effects on Humans

Both cat and dog fleas will occasionally bite humans, but cat fleas are more likely to infest human homes and bite people. According to the Cleveland Clinic (, the flea species that commonly bother dogs and cats don’t tend to live on humans. However, cat fleas are known to develop a preference for biting and feeding on humans in the absence of their preferred feline host.

When cat fleas bite humans, they cause small, red, itchy bumps on the skin. The bites often occur around the ankles and legs. But in severe infestations, fleas may bite anywhere on the body. Cat flea bites can lead to significant itching and discomfort in people. And if scratched, the bites may become infected.

Some people may also develop an allergic reaction to cat flea bites. Signs of a flea allergy include hives, rash, and swelling at the bite site. It’s important to treat and eliminate cat fleas quickly in homes where they pose a problem for residents.


There are several options for treating flea infestations in cats and dogs, including topical and oral treatments, flea collars, sprays, and environmental control.

Topical treatments like Frontline Plus and Advantage II are applied to the skin and spread over the body to kill fleas and prevent re-infestation for about a month. Oral treatments like Capstar, Nexgard, and Simparica are given as a tablet or chewable that starts killing fleas within hours.

Flea collars like the Seresto collar provide ongoing protection by releasing insecticide onto the fur for up to 8 months. Sprays like Vet’s Best Flea & Tick Spray can provide quick but short-term relief when applied thoroughly over the coat.

Environmental flea control is also important. This includes vacuuming floors and furniture, washing bedding on hot cycles, and using sprays or foggers in the home according to label directions to kill flea eggs and larvae. Controlling fleas on any other pets is also essential.

According to VCA Hospitals, “Control of fleas on your pet alone is usually not adequate under heavy infestation pressure and flea populations persist until other stages in the flea life cycle are also addressed.” An integrated approach works best to fully eliminate an infestation.


To prevent fleas from infesting your cat, regular flea treatment is essential. Topical spot-on treatments like Advantage II or Frontline Plus can kill adult fleas and prevent re-infestation for up to a month. It’s important to use these treatments year-round, even during colder months when fleas are less active. Flea collars can also help repel fleas when used along with spot-on treatments.

In addition to treating your cat, be sure to regularly vacuum upholstered furniture, rugs, and carpeted areas to remove flea eggs and larva. Wash your cat’s bedding frequently using hot water to kill any fleas or eggs. By combining preventative topical treatments with thorough cleaning, you can help keep your home flea-free and your cat comfortable.


In conclusion, both dog fleas and cat fleas can be a nuisance for pet owners, but cat fleas tend to pose a greater problem. Cat fleas are able to reproduce faster than dog fleas, and a cat flea infestation can quickly get out of control. Cats are also more susceptible to flea allergies and anemia from flea bites than dogs. However, dog fleas can still bring discomfort, itchiness, and disease to both pets and humans when uncontrolled.

The best approach is to control fleas proactively on all household pets using veterinarian-recommended products. Treat the animals first and then the environment to break the flea life cycle. Keep pets and homes clean and limit contact with wildlife. Monitor pets closely and treat promptly at the first signs of fleas. With vigilance, flea infestations can be contained before they create a major nuisance.

Scroll to Top