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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.


There are many types of parasites that can pose a threat to your cat. In some cases, these parasites and/or the diseases that they carry can also pose a threat to your family. There’s really no need to panic though.


Fortunately, we can control most of these parasites reasonably easily. Here are some of the parasites you should make sure your cat is protected against along with the reasons why it’s important to keep your cat free of them.


  • Fleas are common. Even indoor cats are susceptible to flea infestations. Flea bites are uncomfortable for your cat at best. Even worse, fleas can contribute to skin allergies that may cause serious and painful skin lesions for your cat. These parasites feed on your cat’s blood. If the infestation is severe, your cat may lose enough blood to become anemic. Fleas can also spread other diseases to your cat. For instance, tapeworms are intestinal parasites that can be passed to your cat through the ingestion of a flea. Fleas also play a role in the spread of certain diseases to people. Diseases such as cat scratch disease and even plague are good examples. These diseases cannot be transmitted without the presence of fleas. If you think your cat is free of fleas simply because you don’t see live fleas on your cat, think again. Many cats groom fastidiously, removing the evidence of a flea infestation while doing so, and making the diagnosis of a flea problem even more difficult. It’s always easier to prevent an infestation than it is to try to treat an existing infection.
  • Ticks can also plague cats, particularly those that spend time outdoors. Ticks, like fleas, feed on your cat’s blood. They attach to your cat’s skin via specialized mouthparts, feed on your cat’s blood until satiated, then fall off and continue their life cycle. Ticks can be responsible for spreading other diseases to your cat too. For instance, in some parts of the country, cytauxzoonosis, or “bobcat fever,” is a serious and often fatal disease for infected cats and the disease is spread through the bite of infected ticks.
  • Heartworms are carried by mosquitoes.  Even one mosquito bite can infect a cat with heartworms. We all know that mosquitoes can find their way indoors all too easily, so even indoor cats are not necessarily safe from becoming infected with heartworms. The symptoms of heartworm disease are often very similar to those of feline asthma and the two diseases can be difficult, if not impossible, to distinguish from one another. In some cases though, heartworms can cause sudden death in cats, with no warning symptoms being present prior to death.
  • Intestinal parasites, such as roundworms, hookworms, and coccidia, can infect cats of any age and can cause symptoms such as vomiting and diarrhea. These parasites tend to be most serious in young kittens where diarrhea and vomiting can easily lead to dehydration if not controlled promptly. Most kittens are born with parasites, with roundworms and/or hookworms being the most common, so routine deworming of young kittens and regular fecal examinations for all cats are recommended by most veterinarians. Under the right circumstances, some of these parasites can also pose a threat to people. Roundworm infections can be especially devastating for children, leading to blindness, seizures, and other symptoms.
  • Toxoplasmosis is a protozoan parasite. Cats serve as a definitive host for the disease and are capable of passing the disease to people. Infected cats usually develop only mild symptoms of illness if they become symptomatic at all. However, toxoplasmosis can be particularly harmful for pregnant women. The disease can cause miscarriages, stillbirths, or birth defects if the mother is infected during her pregnancy. There is also some risk for people who have compromised immune systems.


Fortunately, cats that are housed indoors have very little chance of becoming infected with toxoplasmosis. Taking precautions to avoid inadvertent ingestion of foods and beverages contaminated with toxoplasmosis oocysts (eggs) is an effective method of prevention.


These are a few of the most common parasites that affect cats. Check with your veterinarian to determine which parasites pose a threat in your location. Your veterinarian can also help you development a preventive plan to protect your cat from these parasites. While there are many options for parasite control on the market, these products are not all the same. Choosing a product that is safe and effective for your individual cat is of utmost importance.



Dr. Lorie Huston



Image: Bojan Pavlukovic / Shutterstock


Last reviewed on July 31, 2015


Comments  3

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  • Stick-tight Fleas
    07/29/2013 05:44pm

    Here in Western Colorado, we don't see too many parasites, in general, compared to other parts of the country, probably because it's so dry and because the the animal population density is low.

    Anyway, I would say that the most common parasite that I see in cats is the Stick-tight flea. They bury their heads under the cat's skin (so they can't fall off) and are found mostly on the leading edge of the ears, under the eyelashes and where the whiskers emerge on the upper lip.

    They can cause enough irritation to the cat that it will scratch its ears, but I have never heard of them getting on people.

    A spot-on type of flea killer like Frontline has always done a good job of killing them, allowing them to fall off, and preventing further infestations.

    Dr. Bob Turrou

  • Indoor Kitties and Fleas
    07/29/2013 05:56pm

    I, for one, became a believer when my Darlene pranced proudly across the dining room table when a friend and I were sitting there chatting. Since my friend is also a hard-core critter person, I didn't think anything of plucking off (what I thought was) a piece of litter stuck on her backside.

    EEeeeeuuuu. It was a tapeworm.

    Needless to say, everyone was immediately checked for worms and "Advantaged".

  • 07/29/2013 06:04pm

    I'll add that I once saw Cuterebra (acute arebra?) being removed from a cat at a shelter. It was really nasty.

    Is there any way to prevent this? Do the common topical preventatives cover this?

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