Tieton Drive Animal Clinic

3901 Tieton Drive
Yakima, WA 98902




Every year, we recommend dewormer for cats and dogs that go outside. This is confusing to many people, as they don’t physically see worms in their pet’s stool.  However, there are some compelling reasons for our recommendations.

  1. Unless your dog or cat has a really high worm burden (aka lots and lots of worms), you WON’T see adult worms in the stool.  If we do a fecal exam on your dog or cat, we aren’t looking for adults.  We are actually sending the sample to the lab where they centrifuge the stool in a zinc sulfate solution that helps bring microscopic eggs and oocysts to the surface to be seen and counted.  These eggs cannot be seen with the naked eye- you need a microscope.

  2. Even the best fecal test can miss some parasites.  Some common types of worms aren’t constantly shedding eggs, so a single look at a stool sample could miss an important parasite. If your pet is having diarrhea that isn’t responsive to some of our first treatments, we may recommend a broad spectrum dewormer even if the stool sample is technically “negative.”

  3. Many common parasites are zoonotic.  This means that they can infect humans as well- especially children, the elderly, and anyone who is immunocompromised by illness, steroids, or chemotherapy.  But because we are not the normal hosts for these parasites, they do weird things- like migrating through organs, skin, or ending up in the eyes (there was a whole House episode about this).

  4. Parasites are extremely easy for pets to pick up in the environment.  The kicker is that the eggs and larvae hang out in the grass and soil after the poop that deposited them there is gone.  So your dog or cat walks on grass that is playing host to eggs or larvae, licks their feet, and parasite transmission is accomplished!  So just walking outside and engaging in normal grooming behavior is enough to give your pet an unwanted intestinal hitch hiker.

Want to learn more about the most common intestinal parasites?  Check out this link for an excellent discussion of roundworms in dogs (for those who are easily grossed out, there is a small picture of roundworms in a petri dish, but the rest is all just diagrams and cartoons).