Fleas, Ticks, Worms, and Intestinal Parasite Prevention

Parasites aren’t just a health risk for your pet, they can affect you and your family as well. That is why prevention is key! In the Toronto area, we recommend protecting your pet against fleas, ticks, and heartworm. St Clair East Animal Hospital offers several different oral and topical preventatives depending on what is best for your cat or dog.



Fleas are tiny parasites that jump from animal to animal and take blood meals from them. Fleas impact your dog or cat by causing anemia (low red blood cell count), allergic skin reactions, and transmission of some diseases. Having a flea infestation on your pet can lead to an infestation in your home environment that can sometimes be difficult to eradicate. 


Ticks sit on blades of grass waiting to grab on to an animal walking by. Once on the fur of an animal, they embed themselves into the skin to feed on the animal’s blood. Ticks are a concern because they carry many infectious diseases, such as Borrelia (Lyme disease), Anaplasma, and Ehrlichia.

Ear Mites

Barely visible to the human eye, ear mites live on the surface of ear canal skin. As these microscopic parasites feed in a dog’s ear canal, they cause intense itching. A dog suffering from ear mites may be seen repeatedly scratching at his ears or violently shaking his head. If you see dark flecks resembling coffee grounds in your dog’s ears, these are the mites' droppings.

Worms in Dogs

Heartworm disease

Though they are one of the most dangerous parasites in dogs, heartworms are extremely preventable. They are transmitted by mosquitoes and live in the heart and blood vessels of the lungs. Heartworm infection can affect many different organs of the dog but signs of heart and lung disease are most common.

Heartworm is a serious, life-threatening disease that affects both dogs and cats. Heartworm larvae are spread by the bite of infected mosquitoes. Once in the body, the larvae become adults and live in the heart and pulmonary (lung) arteries. It is here that the heartworms can cause deleterious effects. Many dogs are asymptomatic, although others will develop coughing, difficulty breathing, and exercise intolerance. In some cases, heartworm disease can lead to heart failure. We recommend giving your dog heartworm preventative every month from June to November. Heartworm prevention greatly reduces the risk of developing heartworm disease. We recommend testing for heartworm disease yearly at your dog’s annual visit. Follow this link to the Companion Animal Parasite Council to learn more about heartworm disease in dogs.

Roundworms can be contracted in many different ways, frequently from a mother to her unborn puppy. Because there are so many ways for your dog to be infected with roundworms, they are very easy to spread. It is essential to keep your dog’s living area clean and prevent them from eating wild animals.

The name “hookworm” is derived from the hook-like mouth-parts these parasites use to anchor themselves on the lining of the intestinal wall. Puppies should be treated for hookworm at 2,4,6 and 8 weeks of age due to the high rate of hookworm infection in newborn puppies.

Tapeworms are long, flat worms that attach to your dog’s intestines. Dogs commonly contract tapeworms from fleas, mice and other rodents and segments of the worms are often found in on your dog’s rear or in their feces. Though there are few symptoms associated with tapeworms, it is still important to treat them as soon as possible.

The whipworm is a common intestinal parasite in dogs. The parasites reside in the cecum, where the small intestine and large intestine meet. Whipworms can be difficult to diagnose because there are few signs of infection, so regular checkups are important.


Intestinal Parasites

There are numerous species of intestinal parasites that affect dogs and cats. Some of these parasites are zoonotic, which means that they can be passed from animal to human and vice versa. Animals may be asymptomatic, although the majority of animals with intestinal parasites will show clinical signs, such as vomiting, diarrhea (+/- bloody), decreased appetite, abdominal pain, weight loss, and flatulence. Common dog and cat intestinal parasites are roundworms, coccidia, hookworms, whipworms, giardia, and tapeworms. These are mainly spread through the feces, therefore, it is important to use proper hand hygiene and sanitation. The good news is that many of these parasites are preventable! The heartworm preventative also is a dewormer for some of these parasites, which is another reason why we recommend monthly administration.

Other Internal Parasitic Dog Diseases


These tiny single-celled parasites, usually found in puppies, live in your dog’s intestinal lining. Dogs become infected with by swallowing soil that contains coccidia. Left untreated, the parasites can cause diarrhea, weakness and dehydration.

Three Ways to Protect Your Dog or Cat Against Parasites

Get your Dog or Cat Tested Regularly

While it’s fairly common for a dog to become infected with an internal or external parasite at some point, early treatment is crucial. A harmless parasite left untreated could eventually cause a life-threatening illness for your dog and pose a health risk to your family.


Focus on Prevention First

Preventative medicine is a much better option than costly treatments later. Getting your puppy or dog vaccinated and de-wormed regularly allows her immune system to thrive. Adult dogs also benefit from fecal examinations - which allow your veterinarian to diagnose parasites not controlled by monthly medications.


Bring your Dog in for an Annual Checkup

Bringing your dog to your veterinarian for regular parasite checkups is one of the most important things you can do to keep your dog, and your family, healthy. We offer different programs specifically designed for your dog’s stage of life. Schedule an appointment to find out more.