Secrets of the Stool Sample – Part 2  THE WORMS!                           


Continuing our journey into the secrets of the stool sample, let’s learn about those monsters inside us – the worms. There’s a lot of misinformation out there about what worms our animals can be exposed to and infected with, what the symptoms look like and what the true dangers are to both people and animals. Here’s the real scoop on these parasites:

All of the intestinal worms have pretty interesting life cycles which we won’t go into here. What you need to know is that an animal picks up worm eggs, the eggs develop inside various body tissues, go through several larval life stages, develop into adult worms which lay eggs and start the cycle all over again. The eggs are often pretty hard and are designed to last outside in an environment for a long time, sometimes lasting even for years. That’s why it’s so easy for animals to become re-infected with re-exposure. Diagnosis can only be made by your veterinarian or a specialized laboratory after preparation of the specimen and examination under a microscope. Advanced testing methods may be available in the near future. Treatment is usually targeted at treating the worms once inside an animal – it’s difficult to control eggs out in the environment but there are some measures that can be taken. Let’s learn about each of the major types of worms:


  • Appearance -Parasitologists are pretty straight forward about naming worms. Roundworms are worms of varying length with round body shapes. They often look like cooked spaghetti. All warm-blooded animals can be infected with various species of these worms.
  • Clinical Signs – These worms don’t usually cause diarrhea, but can result in poor hair coats,     weight loss, or failure to gain weight. They don’t cause animals any local irritation or itching. You may see adult worms passed in the stool.
  • Treatment- Consists of proper medications administered at regular intervals. In dogs, this may be as often as every ten days. We base dosing on the life cycle of particular worms. Some medications may need to be repeated as often as every ten days. Large animals such as horses and cattle are administered dewormers on a regular basis.
  • Zoonotic Risks – these are dangers to people as zoonoses are diseases people can contract from animals. We are not the main host for these worms. We can ingest eggs which develop into larval forms which migrate through various body tissues causing inflammation in particular organs such as the liver as the worms try to find their way to the proper place and can’t. Some of the migrations can cause serious problems. Raccoons carry a roundworm which can infect dogs  that causes blindness in infected people.
  • Control – since these are very common in an environment this is difficult. Regular administration of an appropriate dewormer is key. Avoid areas of high animal concentrations like dog parks. Large animals often are moved from pasture to pasture to limit re-exposure. HOOKWORMS –
  • Appearance – These are smaller in length than roundworms but also have a round body. There are hooks around the mouth area which help them attach to the intestine giving them their name.
  • Clinical Signs – these worms can cause diarrhea. Their hooks can irritate and inflame the intestine and even cause some blood loss; even enough to cause anemia.  They too can result in poor growth, weight loss and poor hair coat.  Generally too small to be seen passed in stool. They don’t cause rectal irritation.
  • Treatment – Proper medications from your veterinarian administered at appropriate intervals on a regular basis. In dogs, this can be every three weeks.
  • Zoonotic Risk – These worms are easy for people to pick up. The larval forms can burrow through intact skin, making it possible to pick up by walking barefoot in areas where animals have passed the worms. The larvae migrate under the skin causing a rash, itching and can damage skin enough to cause scarring.
  • Control – Same as for roundworms. WHIPWORMS
  • Appearance – These are very small worms and can’t usually be seen with the naked eye. They are narrower at the tail end which makes them look like a whip.
  • Clinical Signs – These often do cause intermittent or chronic diarrhea in animals. This leads to poor condition, weight loss and poor hair coats. They don’t cause rectal irritation.
  • Treatment – Proper medications from your veterinarian administered at appropriate intervals on a regular basis. In dogs, this can be every three months.
  • Zoonotic Risk – low potential to cause any signs in people.
  • Control – Same as for roundworms. 


  • Appearance – These are flat worms with a segmented appearance. They sometimes reproduce by breaking off segments. These can be seen in the stool as small white particles which often look like grains of rice.
  • Clinical signs – Rarely cause any signs in infected animals. Heavy infestations can result in weight loss.
  • Treatment – Proper medications from your veterinarian administered at the appropriate regular intervals. The majority of over the counter dewormers do no treat this parasite. Neither do the monthly heartworm preventatives which may treat all of the other worms discussed here. In dogs, treatment intervals are usually ten days. Not all large animal dewormers treat tapeworms also. Read medication inserts carefully and consult your veterinarian.
  • Zoonotic Risk – most common tapeworms are low risk for causing any problems in people. There is one type of tapeworm which animals can carry which can cause serious consequences in people. Fortunately it’s very rare in our area.
  • Control – Deworming with an appropriate medication at the proper interval. May be ten days in dogs. Some tapeworms of dogs and cats can be carried and transmitted by fleas. Therefore, increased flea control methods may be required. You’ve now learned that intestinal worms are common in our area. Some of these parasites can cause varying degrees of debilitation and illness in our animals. Many can also infect people with many degrees of severity. The Companion Animal Parasite Council ( maintains an extremely helpful website with the best information available. One of their most interesting features is an interactive map which breaks down the current prevalence of each parasite down to the county level based on data from the two largest national veterinary laboratories.  Click on the link,  pick a parasite, click on New York, then click on your county to find out just what the risk is right outside your door.

    Parasite control is important for both animals and humans. Consult your veterinarian for testing and treatment now that you know a few more secrets of the stool sample.


    Roundworms                   Hookworms                 Whipworms                 Tapeworms




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  • Blog Author

    Dr. James Zgoda

    Education: University of Pennsylvania, B.A. Animal Behavior 1980 Rutgers Univ., M.S. Zoology 1981 Cornell University College of Veterinary Medicine, D.V.M., 1985 Owner and chief veterinarian of Otterkill Animal Hospital in Campbell Hall, NY ... Read Full
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