Intestinal Parasites in Dogs and Cats

Why does your veterinarian want to check a stool sample? Dogs and cats can carry several internal parasites. The most common are roundworms, hookworms, whipworms, tapeworms, coccidia, and giardia.

Of these four only two are commonly seen in the stool with the unaided eye: roundworms and tapeworms. Although they can vary in size or shape, roundworms generally look like spaghetti, and tapeworm segments generally look like rice grains. Other parasites are so small that they must be diagnosed by antigen testing or microscopic evaluation.

  Roundworms Hookworms Whipworms Tapeworms Giardia Coccidia
Pass to humans? Yes - visceral larval migrans Yes - rarely skin rash No Rarely Unlikely No
Where do they get it from? Born with them, or environment Environment, nursing Environment Fleas Environment, standing water Environment, other animals
Transmit to other animals? Yes Yes Yes Yes Yes Yes - only same species
Cause life-threatening disease? Yes in young animals Yes - death in young animals Yes in young animals Rarely Rarely Yes in young animals
Signs Diarrhea, vomiting, pot belly, weight loss, long worms in stool or vomit Bloody diarrhea, weight loss Diarrhea, weight loss Weight loss, scooting, worms in stool (like rice) Diarrhea, vomiting Diarrhea, soft stools, weight loss

Why should my veterinarian check a stool sample?

  • Early diagnosis - to prevent the problems listed above.
  • Correct treatment - different parasites are treated differently. Over the counter dewormers do not treat all parasites.
  • Some parasites can be passed to people - these include roundworms, hookworms and tapeworms. They can be dangerous in small children and the immunocompromised.


  • Clean up feces regularly.
  • Scoop litter daily.
  • Pick up dog feces immediately so that your dog does not contribute to contamination of soil.
  • Deworm regularly as recommended by your veterinarian. Generally, prescription wormers and safer and more effective than over-the-counter worm medications. (Monthly heartworm preventions usually contain intestinal parasite dewormers).
  • See your veterinarian when problems occur.

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