Intestinal Parasites

Roundworms, Hookworms, Whipworms, oh my! A recent study found that 33.9% of dogs and 31.8% of cats that came from shelters were positive for an intestinal parasite. Pets that are left untreated for parasites pose a risk to other animals and humans. At Barriefield Animal Hospital, we recommend routine deworming and fecal testing for all pets. In 2018, we saw many dogs and cats come up positive for roundworms, hookworms, whipworms, tapeworms and giardia with fecal testing.


Roundworms are the most common intestinal parasite seen in cats and dogs. They are long and thin and can resemble spaghetti. Cats and dogs can be infected with roundworm by ingesting eggs that reside in soil, feces, and mice and other small mammals. Puppies and kittens can also contract roundworms from their mother. Roundworms are a zoonotic parasite, which means they can be passed onto humans. Children are vulnerable to infection as they are more likely to put dirt and other contaminated objects into their mouth.


Hookworm eggs are passed in feces and hatch into larvae which live in the soil. Dogs and cats can be infected by ingestion through grooming or skin or feet contact. Puppies and kittens can be infected by ingesting their mother’s infected milk. Humans can be infected with hookworms through skin contact. It is often due to walking barefoot on a beach. Hookworms attach themselves to the intestinal lining and feed on your pet’s blood. It can lead to anemia and can be life-threatening in young pets.


Whipworm infection is uncommon in cats in North America but can be found in up to 10% of dogs in Ontario. Whipworm eggs are hardy, are resistant to extreme temperatures, and can remain in the soil for several years. Dogs become infected by ingesting eggs from their contaminated environment.


Tapeworms are long flatworms, made up of many segments. Segments look like grains of rice and can be found on your pet’s fur around its hind end. Cats and dogs can be infected with tapeworm by ingesting infected rodents or ingesting fleas during grooming. An emerging tapeworm, Echinococcus, is transmissible to humans and can cause major health issues to dogs and humans. Fortunately, it is still an uncommon parasite in Canada but is becoming more recognized.


Dogs and cats can be infected with giardia by contacting contaminating infected feces from other pets that are infected with this single cell parasite. Transmission from dogs and cats to humans is rare.

What are some signs that my pet has intestinal worms?

Intestinal worms can cause gastrointestinal upset, such as diarrhea (with or without blood), vomiting and inappetence. Lethargy and weight loss can occur with heavier infections. If a puppy or kitten has an abundance of intestinal worms, they can often have a pot-bellied appearance. Owners may also see full worms or segments of intestinal worms around their pet’s hind-end or in their fecal matter. Many animals with parasite infections show no symptoms at all.

How do we treat and prevent intestinal worms?

For dogs, there is deworming medication included in most heartworm prevention products. It means that they will be dewormed every month when receiving their heartworm prevention medication. There are topical and oral deworming medications for your cat. Healthy adult pets should have a fecal test done. Puppies, kittens and new pets should be tested shortly after adoption. To reduce the possibility of transmission of parasites, it is recommended to pick up your dog’s feces in your yard daily. Thoroughly wash your hands after dealing with your pet’s urine or feces.

Written by: Lily Mccallum, RVT


1. Villeneuve A, Polley L, Jenkins E, Schurer J, Gilleard J, Kutz S, Conboy G, Benoit D, Seewald W, Gagné F. Parasite prevalence in fecal samples from shelter dogs and cats across the Canadian provinces. April 2015. Parasites & Vectors 2015, 8:281