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Interceptor is recommended year-round to prevent/control internal parasites

Intestinal Parasites

The most common internal parasites we see here in the Yampa Valley include the intestinal parasites tapeworms, roundworms, and giardia. Fortunately, most monthly heartworm preventions, like Interceptor, include a medication to limit or eliminate the burden of the intestinal parasites hookworms, roundworms, tapeworms, and whipworms. In most other areas of the country, all of these parasites are common, especially among breeding facilities. Internal parasites are diagnosed by fecal testing.



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Roundworms are very common in puppies and kittens and are the primary reason for deworming all puppies and kittens.

Tapeworms are introduced to the intestinal tract of dogs and cats when they ingest fleas. Even if your pet does notInternal Parasites 3 have fleas, they can contract tapeworms by ingesting rodents that do have fleas. For this reason, we highly recommend deworming cats that go outside, every 6 months. Tapeworms look like pieces of rice in the stool (pictured).

Giardia is a protozoa which is found in cold water sources. There is no prevention currently available for it but a course of antibiotics generally clears up the infection.

Coccidia is another parasitic protozoa that lives within the intestines and can be treated with an oral dewormer.                   Coccidia is most commonly found in breeding facilities.

Hookworms and whipworms are both intestinal parasites that are more commonly found in warmer regions. Our patients will usually only encounter them when traveling to or being bred in other parts of the country.

The symptoms of an intestinal parasite infection include:

  • diarrhea
  • vomiting
  • weight loss or failure to thrive
  • poor coat condition
  • changes in appetite

There are often no symptoms indicating the presence of intestinal parasites which is why we recommend annual testing as part of the wellness visit. Testing requires the submission of a fecal sample that is less than 24 hours old.  We send the sample to an outside laboratory for microscopic examination and usually obtain results the next business day. We cannot send samples out on Saturdays.

Fore more info on the above parasites:

Handouts on intestinal parasites: 
Pets, Parasites & KidsTapeworms
Roundworms – Dogs
Roundworms – Cats
Roundworms – Humans
(Giardia is not a worm but a GI parasite)

Heartworm Disease

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Heartworms are an extremely common internal parasite in most areas of the country and although they are not commonly diagnosed in this area, they are usually fatal to their canine hosts. Heartworms are carried and transmitted by mosquitoes. It takes several years after being infected before dogs begin to show signs of heartworm disease. That is why we recommend heartworm testing annually especially if the patient has been off of heartworm prevention. The test does not detect infections acquired during the previous 6 months.  For this reason, we do not tests puppies, instead we recommend testing at the patient’s first adult annual examination.

To prevent heartworm infection and to limit intestinal parasite infection, we recommend keeping dogs on heartworm prevention all year round.

Heartworms in cats is more complicated. Cats can contract heartworm disease but it’s not as common in cats. In most cases of feline heartworm disease, only one worm survives to adulthood and the disease becomes self-limiting since the worm will live out its lifetime of 3-5 years and die, causing no long-lasting harm to its host. Additionally, the antigen heartworm test which is what is used with dogs, is not effective in diagnosing heartworm disease in cats. Additional testing can be done but is still only minimally accurate.

Handouts on heartworm disease:
About the Parasite
Heartworm Prevention
Heartworm Treatment

Website of interest:
American Heartworm Society

For more information about dogs and parasites, please visit:

For more information about cats and parasites, please visit: