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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.


It’s a dilemma I see often in my veterinary practice — indoor cats that have parasites. Many cat owners believe that keeping their cats indoors protects them from parasite infestations and/or infections. Unfortunately, that’s not always true.


Indoor cats can become infested with fleas quite easily. Disturbingly, fleas can overwinter in your home very easily as well. Even outdoors, under the right circumstances, fleas can be active in the winter. Indoors, fleas are never exposed to freezing temperatures or other adverse weather conditions, making it easy for these parasites to survive indefinitely.


To make matters even worse, fleas can be difficult to find. Being fastidious groomers, many cats remove the evidence of an active flea infestation from their skin and hair coat, leaving an unsuspecting cat owner with no idea that there is indeed an existing flea problem.


Tapeworms also can be a problem for indoor cats. Since tapeworms are carried by fleas, this should come as no great surprise. Your cat can get tapeworms by swallowing a flea that is carrying tapeworms. This can happen when your cat grooms. Grooming activity can result in ingestion of live fleas.


Roundworms also may be a threat to indoor cats, particularly if there is a rodent problem in the home. Mice can enter a home through very small openings, sometimes even as small as a quarter. It’s not unusual to find a rodent problem even in a well-maintained home. Cats, being the predators that they are, will naturally hunt these animals, even when well-fed. I’ve experienced this myself, finding my cat Dillon with a mouse. It was surprising because I had found no evidence of mice in my home prior to the incident, nor have I found any signs since then.


Heartworms are another parasite that can infect cats that are housed strictly indoors. Heartworms are passed through the bite of an infected mosquito. We all know all too well that mosquitoes can find their way indoors. It only takes one bite to pass the parasite along to your cat.


Clearly, it is far from impossible for an indoor cat to suffer from both external and internal parasite infestations. So what can you do to protect your cat?

  • Use a safe and effective flea product to prevent flea infestations. Consult your veterinarian for help in choosing the best product for your cat. Follow the directions on the label carefully when using a flea product. Do not use flea products not specifically labeled as being safe for cats. Many products that are safe for dogs are not safe for cats.
  • Administer a monthly heartworm preventive medication to your cat year ‘round. Many of these products also provide some protection against roundworms and hookworm infections.
  • Have your cat examined by your veterinarian on a regular basis.
  • Have your cat’s feces examined periodically for parasites. This should be a microscopic examination performed by your veterinarian. It is possible to see adult roundworms or tapeworm segments in your cat’s feces. If you see worms in your cat’s feces, bring the worm to your veterinarian for identification.


Living indoors (or primarily indoors with leashed walks outdoors and/or access to an outdoor enclosure) is the safest lifestyle for your cat. However, your cat is not safe from parasites even if living indoors. It is important to take the proper precautions to protect both yourself and your cat.


Dr. Lorie Huston


Image: Sammy by Erik Eckel / via Flickr

Comments  2

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  • Tapeworms!
    03/04/2013 05:55pm

    I can attest to the truth in this article. My kitties have always been totally indoor cats.

    Years ago, a friend and I were sitting at the dining room table just chatting. Darlene (cat) was parading back and forth on the table in order to be the center of attention. I noticed what I thought was a piece of litter stuck to her backside, so I simply picked it off. Ack! I was a tapeworm.

    I still get the heebie-jeebies thinking about it.

    Darlene went to the vet for a fecal check and tapeworm medication. All the others were immediately Advantaged.

  • Indoor cats and heartworm
    03/06/2013 08:27am

    Thank you, Dr. Huston for your timely and accurate post. The American Heartworm Society posts Guidelines for the Diagnosis, Treatment and Prevention of Heartworm Disease on our website www.heartwormsociety.org. Many, if not most cat lovers do not understand the risks of parasite infestations, even in their indoor-only friends. In my practice, a significant number of the cats we see that test positive for heartworm are indoor-only or indoor-mostly. As President, I speak for the entire board of the American Heartworm Society in expressing my gratitude for your efforts to get great information out to the cat-owning public.

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