Tapeworms – you can see ’em, the lab can’t!

This scenario plays out in vet clinics across the country. It happened to me before I went to vet school! Hopefully, front desk staff at vet clinics is getting better at communicating to avoid these mix-ups.

You are picking up your dog or cat’s poop, and you see tiny white worms.

They are moving in and out of the poop. Seriously, they could not be any grosser.

This is the stuff of horror movies!

You scream, drop the poop…then pick it up because you don’t want these worms getting to anyone. (We do crazy things when panicking!)

You call your vet office, who tells you to bring the sample. The receptionist takes the poop, hands it to a technician, and they send it to the lab for testing for parasites.

You get a phone call that the fecal test came back negative. No parasites.

You’re thinking “I’m not crazy!! I KNOW what I saw!”

And you’re kind of freaked out because this needs to be addressed and fixed, and you feel it’s being ignored.

Such is the world of the tapeworm. What’s going on?

puppy kitten veterinary adviceWhen we veterinarians (or the lab testing companies we use) test fecal samples for intestinal parasites, the sample in mixed with a very specific concentration of solution. It is then placed into a centrifuge, to separate out the varying weights (on a microscopic level) of parasite eggs. Most parasites reveal themselves by releasing eggs into the intestines, and therefore the poop…it’s also how they spread to other animals to keep the species going. Some parasites, we’ll actually see the whole organism!

After we take it out of the centrifuge, we look at the top layer (where all the good stuff is) under the microscope. Based on the eggs (or organisms) that we see, we can identify what is living inside your dog or cat.

Tapeworms are rebels. They do not release eggs like most other worms. So when we’re looking under the microscope, there’s nothing to see! What tapeworms do release are proglottids – those little white segments of grossness writhing around in the poop. You might also find the dried out version near your pet’s rear – they look like little grains of rice. Careful, once I was with a patient who actually had rice on his bottom, no tapeworms, so recall if you happened to have Chinese food the night before!

Good news – those gross tapeworm segments you’re seeing cannot infect you, your kids, or your other dogs and cats. The most common way our dogs and cats get tapeworms is from fleas. Specifically, by swallowing fleas. When they are itching and biting (or, with cats, grooming) they are potentially swallowing the flea causing them to itch.

So does tapeworms in your pet’s stool mean you have fleas? No, but it means fleas are part of your pet’s past. I have some owners who adopted a dog or rescued a cat a year ago, and just then start seeing tapeworms. It could be from their “pre-you” life! Of course, it’s always a good idea to have your vet check your pet out for fleas. What’s the point of treating tapeworms if they have fleas and will just reinfect themselves?

The less common way dogs and cats get tapeworms is from hunting – and consuming their prey. If your dog catches the rabbit, but it’s intact, he won’t get tapeworms. If he eats it, then he has potentially other problems, and tapeworms are on the list. Cats who go outside are much more at risk, as consumption of rodents (again, the ones that are killed and presented to you intact, so lovingly, don’t count) can bring tapeworms into your cat’s system.

The good news – tapeworms are easily treatable! For dogs, there’s tasty pills, and for cats, there’s even a topical treatment available! (no more cramming the huge pill into your cat!). There’s an older injectable form of the drug as well that is still in use.

And final warning – when you treat the tapeworms and they are evacuating the animal, they exit through the back door. Translation – you might see gross worms for a day or two. Just clean them up from the litter box or yard and move on – and be happy they are leaving your pet!

Posted in Parasites.


  1. Dear Vetchick,

    Omg, I am going exactly through this at this very moment! I have been giving my Welch and Fox Terrier Milbemax every week for 4 consecutive weeks and I am still seeing tapeworm segments. The vet here in New York, (my first time visiting them,) says the test is negative but if I feel sure they have worms give them Drontal Plus for 3 consecutive days. My Welch has had elevated liver enyzmes in the past and Im worried about giving her such a nuclear treatment. I would appreciate any insight you could give me, many thanks in advance.

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