Puppy Parasites: Preventing, Diagnosing, and Treating Parasites in Puppies · The Wildest

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Puppy Parasites 101: What You Need to Know to Keep Your Pup Safe

Does your pup have a pot belly? Have you noticed something moving in their poop? Yep — it’s time to talk about puppy parasites.

by Agnes Molek, MA
October 1, 2020
One month old brown brindle Jack Russell puppy lies on a woman's lap. She strokes the dog's soft tummy. Mother dog is watching nearby.
Photo: Dasya / Adobe Stock

If you’re a new pet parent and you’ve noticed something strange (maybe even wiggling) in your pup’s poop, been concerned about your puppy’s potbelly, or reached out to your dog’s veterinarian about bloody diarrhea, you aren’t alone. The majority of the time, the answer to these questions points to a group of nutrient-depleting and blood-sucking culprits: intestinal parasites. Time to read up on some important information about intestinal parasites and your pup’s pooping habits. Here’s everything you need to know about puppy parasites.

What is a Parasite?

A parasite is an organism that feeds and lives on (or in) another animal (such as a dog), causing them harm or even death. Intestinal parasites can range in size, shape, route of transmission, and how they affect dogs, but as the name suggests, they are found somewhere along the pet’s gastrointestinal tract — like the stomach or small and large intestines. Puppies are more likely to have severe symptoms from parasites because blood and nutrients are being taken away during a crucial time of growth and development.

How do puppies get parasites?

There are many ways a puppy can get infected with a parasite because they can be transmitted differently for each kind of intestinal parasite. Your puppy may get a parasite by doing something as simple as standing on grass that has parasitic larvae on it, through a flea bite, or they can even be born with it. How is that possible? It all goes back to mom.

If a pregnant mom gets infected with an intestinal parasite, the parasites may transmit while they are still in utero. Another possible route from mom to puppies is during nursing, where the parasite is transmitted through mom’s milk. But let’s say that while pregnant, the puppy’s mom tested negative for any and all possible intestinal parasites. However, a few months ago, she tested positive and completed the entire deworming process. During the initial infection, it is possible that some of the parasitic larvae migrated into muscle tissues, where they lay dormant until the perfect opportunity, in this case, pregnancy, arose.

Common Puppy Parasites

Now that you’re aware of these pests, it’s time to dive into the nitty-gritty of intestinal parasites. Below you’ll find a list of the most common intestinal parasites your pup can get, how they are transmitted, symptoms to look for, and different treatment options and preventative measures that should be considered.


One common puppy parasite is ancylostoma caninum, commonly called hookworm. There are several ways a pup might be infected with hookworm, including: through ingestion of contaminated poop or soil, when a parasite larvae burrows through the skin (seriously) when standing or laying on contaminated ground, prenatal infection (from mom to offspring in utero), and transmammary infection (from mom to offspring while nursing). Hookworms are zoonotic parasites which means they can be transmitted to humans. Yikes. Symptoms of hookworms in dogs include:

  • Dry or dull haircoat

  • Anemia

  • Pale gums

  • Lethargy

  • Bloody diarrhea

  • Significant weight loss or inability to gain weight

Treatment for hookworms is usually oral dewormers (anthelmintics), which only kill adult worms which means your pup will need to repeat treatment about two to four weeks after the first treatment.


Another parasite to watch out for is Roundworm (toxocara canis and toxocara leonina). Puppies can get infected with roundworms by, you guessed it, sniffing or licking infected poop from another animal. They can also get roundworms if they eat other animals like rodents, earthworms, and birds which are infected by roundworms. Similar to hookworm, it’s also possible to get roundworms through both prenatal and transmammary infection. And, yup, roundworms can be transmitted to humans too. Just like hookworms, your pup will need to go through two rounds of oral dewormers to treat their roundworm infection. Symptoms of roundworms in dogs include:

  • “Spaghetti” in your pup’s poop or vomit

  • Recurrent diarrhea

  • Potbelly (puppies)

  • Lethargy

  • Stunted growth (puppies)


Dogs often get infected by giardia (giardia duodenalis) by drinking water that has been contaminated by poop from an infected animal, but they can also get it by eating something contaminated by infected poop, like grass or dirt. Not all pets show symptoms of giardia. When dogs do show symptoms of giardia, they include:

  • Diarrhea

  • Lethargy

  • Dehydration

  • Weight loss

  • Inability to gain weight

Vets will typically prescribe a combination of fenbendazole (dewormer) and metronidazole (antibiotic) for about ten days as a treatment for giardia. After that, your pup will need to be retested two to four weeks after finishing the medication. 


Another common parasitic worm in dogs is the whipworm (trichuris vulpis). Pups can get infected with whipworm by accidentally eating eggs present on contaminated soil, grass, or poop. Common symptoms of whipworms include:

  • Chronic watery, bloody diarrhea

  • Significant weight loss

  • General debilitation (inability to conserve salt, leading to chronic dehydration)

It’s tough to test for whipworms because they rarely pass eggs, so fecal samples often come back false negative. The most common dewormers used to treat whipworms are fenbendazole and febantel.


Like many of these parasites, it’s pretty easy for your pup to be infected by tapeworms. Your pup can be infected with tapeworm (dipylidium caninum ) if they eat an infected flea, undercooked or raw meats, or contaminated feces. Unfortunately, some forms of the taenia and echinococcus species of tapeworms can also be transmitted to humans. Symptoms of tapeworm in pups include:

  • Moving “rice-like” segments found around pup’s bum or in their poop

  • Weight loss

  • Diarrhea

  • Lethargy

  • Distended abdomen

Tapeworms often don’t show up on fecal screenings but can be seen without a microscope (wiggling stuff in your pup’s poop). Treatment of tapeworm in dogs consists of one or two rounds of praziquantel dewormer, which generally covers all tapeworms types. Though sometimes, pets may be treated with fenbendazole, which does not kill dipylidium caninum.

Preventing Puppy Parasite Infections:

If all this information has you thinking about the last time you had your pup tested for intestinal parasites, this is your sign to get your dog’s poop checked. Intestinal parasites can be very scary — while treatment is usually easier than you might think — prevention is always best.

  • Make sure your new pup is up-to-date on their immunizations.

  • Pick up your pet’s poop to prevent the spread, transmission, and reinfection of the parasite.

  • Practice good hygiene, like washing your hands after picking up feces.

  • Make sure your pup has clean water accessible at all times to avoid drinking from puddles.

  • Limit exposure to areas where excessive dog poop will be.

  • Many heartworm preventatives contain deworming medication that will kill intestinal parasites.

If your pup is experiencing any of the symptoms mentioned, do your dog and yourself a favor and get their poop tested for possible parasites. It’s easy. To test their poop, simply bring in the freshest poop sample you can find, and the clinic staff will do the rest. Veterinarians typically will have results generally within the next 24-48 hours.

Agnes Molek

Agnes Molek, MA

Agnes Molek has her Master’s degree in Biology through Chicago Zoological Society’s Brookfield Zoo connection to Miami University Oxford. She has a Bachelor’s in Biology with a minor in Psychology. She is a veterinary technician at a small animal and exotic veterinary clinic and has two very energetic hounds named Kona and Kaiser.

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