dog chasing tail

Round(worms) and Round Again

Roundworms are stout, plain worms. They tend to live in the small intestines of infected pets. They are probably the most common worm seen in poop. Sometimes pets will vomit up live roundworms as well.


The Roundworm Life Cycle

Pets initially get roundworms either by eating eggs from the environment, eating animals infected with eggs, and through transplacental transmission from mom to puppies. 

After ingestion, the eggs develop into larvae and travel to the small intestine and become adult worms. After transplacental transmission, the larvae migrate through the liver, lungs, and are eventually swallowed to develop in the small intestines. 

The adult worms shed eggs in the feces that eventually make it to the environment to start the process all over again. This is why it is important to clean up after your pet right away – especially in public spaces!

Roundworm Life Cycle


There are several medications available to treat roundworms, including the monthly intestinal parasite preventions! If you have brought a puppy to us, then you have likely seen us give an oral medication called Strongid. This is a type of deworming medication that treats roundworms (and other intestinal parasites). We routinely deworm puppies because they likely picked up parasites from their mom, and since they are young they are more susceptible to other infections as well.


Many monthly preventions also treat active roundworm infections in addition to preventing future infections. That is another reason why it is important to start your pet on a monthly prevention early in life and keep them on the prevention life long! Roundworms don’t have a season – they can be found in the environment or in prey on even the coldest days!

The most common preventions we recommend that treat and prevent roundworms include Interceptor Plus, Heartgard Plus, and Simparica Trio. This is not a complete list though, so ask your veterinarian which prevention is the best for your pet.

Interceptor Plus
Interceptor Plus (monthly oral prevention)
Heartgard (monthly oral prevention)
Simparica Trio
Simparica Trio (monthly oral prevention)


Roundworms are considered zoonotic, which means they can be transmitted to humans! So when you put your pet on prevention you are not only protecting them – you are also protecting yourself and your family from a potentially dangerous infection.

Roundworm Testing

We test for roundworms by looking at fecal samples! The sample undergoes some processing in order to filter out some of the debris and make it easier to identify what we are looking for: the eggs that are shed in the feces.

roundworm egg
Roundworm Egg


  • Roundworms are some of the most common worms we see.
  • Roundworms can be transmitted by eating contaminated environment, contaminated prey, or transplacentally from mom to puppies. 
  • Roundworms can be treated in many different ways, but it is always best to prevent infection in the first place. 
  • It is important to clean up after your pet to prevent contamination in the environment. 
  • Roundworms are considered zoonotic, which means they can be a threat to you too!

Now It’s Your Turn!

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