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Key takeaways

Fleas are parasitic insects that reside and feed on the skin of animal hosts, including cats. Fleas are found worldwide and year round.

  • Cats may be exposed to fleas at any time, but large-scale infestations are easily prevented -Fleas are usually diagnosed by identifying an adult flea or “flea dirt” in the cat’s fur
  • Some cats are allergic to flea saliva and develop an itchy rash when bitten by fleas
  • Severe infestations can cause anemia
  • Fleas can also transmit infectious diseases to humans, making prompt treatment of fleas an important public health concern
  • Treatment of flea infestation involves treating both the cat and its environment
  • There are many flea products available for cats, both over-the-counter and by prescription
  • Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets, especially cats.
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A closer look: Flea Infestation in Cats

Fleas are a concern for nearly all pet parents. They’re very common in most temperate outdoor environments, particularly in shady and moist areas like under bushes, under decks, or in dense vegetation.

Finding a flea on a cat is not an emergency; however, steps must be taken in order to prevent further infestation. Fleas brought into the home can establish themselves in carpets, crawl spaces, or between cracks in hardwood floors. An established flea population in a household can be extremely difficult to remove. It takes at least three months of treatment to successfully eliminate an existing flea population.

Flea-infested cats consume large numbers of fleas as part of their grooming process, which can transmit tapeworms to the cat. Severe flea infestations can also cause anemia, due to severe blood loss from flea feeding.

Fleas pose a serious health risk to humans and other animals because they can transmit serious diseases such as plague, cat scratch fever, and tularemia. Year-round, lifelong use of a veterinarian-approved flea product is recommended for all cats to minimize the risks for flea-borne illnesses in humans, and to prevent the hassle and expense of trying to eliminate an established flea population.

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Risk factors

A flea comb can help pet parents identify adult fleas and flea dirt. Flea dirt describes small specks of host blood that are excreted by the flea as it feeds. It appears as small, black or dark red specks on the skin or in the cat’s bedding and turns red if it gets wet.

Severe flea infestations, particularly of small cats or kittens, can cause anemia due to significant blood loss.

Some cats are allergic to flea saliva, a condition called flea allergy dermatitis, which causes a rash.

Fleas carry the infectious form of tapeworms, allowing a cat to become infected when it ingests fleas during grooming. Tapeworm infestation is often asymptomatic, but outward signs can include weight loss and a dull, unkempt coat. Fleas are a primary source of exposure to tapeworms for cats, so the presence of tapeworms may suggest a co-infestation with fleas.

Possible causes

Cats can be exposed to fleas at any time, even if they live exclusively indoors. Adult fleas on other infected hosts lay eggs which fall off into the environment, eventually hatch, and go through a larval stage before pupating. Flea pupae can survive in the environment for up to a year, withstanding freezing, drying, and insecticides, while waiting for an appropriate host. Once conditions are suitable, the flea emerges as an adult and jumps onto a host.

Cats are exposed to fleas when they pass through or spend time in an environment where other flea-bearing animals have been. Although it is uncommon for fleas to feed on a person, they can use humans to “hitchhike” into the home and gain access to indoor-only pets. Outdoor cats are at a much higher risk of exposure to fleas.

Indoor environments provide the ideal temperature for flea development, allowing them to thrive. Therefore, it is important to keep cats on year-round vet-approved flea preventative medications specifically for cats, even if they never go outside.

Main symptoms

Cats do not always show outward signs of flea infestation.

Testing and diagnosis

Fleas are readily diagnosed by examining the cat’s skin and using a flea comb. Identifying adult fleas or flea dirt is sufficient to make a diagnosis. The absence of fleas upon examination does not rule out the presence of fleas or flea-borne illness.

Steps to Recovery

Treatment of fleas is a multistep process involving elimination of the parasites from pets and their environment. Every pet in the home must be treated, as fleas spread to all animals in the household.

Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets, especially cats.

Successfully eliminating an existing flea population takes at least three months due to the flea’s complex life cycle and the high number of offspring each flea is able to produce.

With regular use of external parasite control over a three-month period, all eggs in the environment hatch and are killed, eliminating the infestation. Some topical products shed into the environment along with the pet’s dander to target eggs and larvae where they are found.

Cleaning of the environment to physically remove eggs, larvae, and pupae can speed along the process of eliminating the infestation. This should include:

  • Vacuuming or steam cleaning carpets, vehicles, and upholstered furniture
  • Washing all pet bedding and soft toys in hot water and drying at the highest heat setting. Buying new soft items may be necessary
  • Washing all human bedding
  • Keeping cats indoors

For outdoor cats, making the yard undesirable to fleas also helps prevent reinfestation. Installation of fencing to prevent wildlife movement, removing piles of leaf litter, mowing the grass frequently, or trimming trees to increase sunlight are all environmental controls to minimize flea populations. Blocking off areas that are cool, shady or moist to prevent feline access is also helpful.

Always use vet-approved pesticide sprays in or around the home. Many pesticides are lethal to cats, so use only products recommended by a veterinarian.


Fleas are contagious to mammalian household pets like dogs, cats, rabbits, and ferrets, as well as wild animals. They are primarily transmitted when the eggs from adult fleas fall off the host into the environment.

Adult fleas may hop onto people to feed, but humans are not their preferred host. Fleas cannot successfully carry out their life cycle and maintain a population with only human hosts.

Flea infestation is prevented by routine monitoring of pets for evidence of fleas, environmental controls, and year-round use of vet-recommended flea control medication for all household pets.

Is Flea Infestation in Cats common?

Fleas are a very common external parasite of cats. The level of infestation is controlled by adherence to robust flea-control practices.

Typical Treatment

  • Antiparasitics (flea control products)
  • Environmental controls

Secondary illnesses related to flea infestation (such as tapeworm infestation) are treated as needed according to current medical guidelines.

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