Why Does my Puppy Have Worms After Being Dewormed?

I have a 4 month old shih tzu, she has had all her puppy shots and worm treatments. Today, I looked at her poop and...


I have a 4 month old shih tzu, she has had all her puppy shots and worm treatments. Today, I looked at her poop and i see worms. Why, if we have had her treated, would she have worms?

sylva, nc

Two main types of worms are common in puppies. Roundworms are the more common and more serious parasite. Puppies usually catch roundworms from their mothers in the uterus or while nursing. Roundworms can spread to humans (especially children) and make us sick.

It isn’t common to see roundworms in a pet’s stool, even if the pet is infested. They are long, thin, and white when they are seen. Most of the time they look like vermicelli noodles.

The Companion Animal Parasite Council and other authorities recommend treating all puppies repeatedly for roundworms. Puppy dewormings usually are designed to remove roundworms.

Tapeworms are a second common type of worm. The most common type of tapeworm is spread by fleas (animals must eat a flea to contract it). Tapeworms are less dangerous than roundworms, although they also can spread to humans–if we eat fleas.

Tapeworm segments frequently are visible in the stool of infested animals. The segments look like rice grains (when wet) or like sesame seeds (when desiccated).

The most commonly used puppy dewormers remove only roundworms. They do not remove tapeworms. I’m guessing that you’re seeing tapeworm segments in your puppy’s stool.

There are, of course, other types of worms as well. I recommend that you take a stool sample to your vet. Analysis of the stool will allow identification and removal of the parasite.

4 thoughts on “Why Does my Puppy Have Worms After Being Dewormed?”

  1. We recently adopted a puppy from a breeder who falsified an adoption contract that insisted the puppy had recently been to her vet and was dewormed/ currently worm free and healthy. The night we adopted the puppy he was up all night screaming and purging very long worms (3 1/2# puppy with 3 inch spaghetti worms coming out in diarrhea) the local vet referral hotline said he needed to go to the veterinary hospital. He was tested for worms and they were determined to be roundworms- he was treated with dewormer. Since then he’s needed more worm medication at least once every week because the worms keep coming back. The worms spread to our previously worm free kitten and she has had to be treated twice now. The puppy has had 7 treatments and is barely 3 and a half months old. I don’t know what to do with his worms being so resistant to the Medication.

  2. We are fostering a dog for the first time. The dog was dewormed a week ago but we are still seeing them in his stools. How long should they take to leave his system?

  3. I gave my puppy pieces of over riped bananas last night. She pooped out visible roundworms this afternoon. Are bananas a natural dewormer. She has dewormer medicine. We thought they were all gone.

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