Canadian Parasites – Where to Find Them and How to Treat Them

In each region of Canada, you will encounter different parasites, each with its own set of problems and treatments. Below is a list of each province and their corresponding parasites.

British Columbia

In BC, there are several internal and external parasites that can affect us and our pets. Fleas are among the most common. Despite misconceptions, the winter in the Lower Mainland does not get cold enough to kill off fleas effectively. When it starts to get cold, the fleas move indoors where they can carry out their life cycles- reaping havoc on our pets.

In Northern, BC temperatures are low enough that you do not have to worry about fleas during the winter months. You can comfortably treat your pet from spring to fall without too much concern. We recommend speaking with a veterinarian regarding the treatment options for your pet.

Ticks are another common parasite in BC. There are three major ticks to look for; Western Black Legged Tick (Deer Tick), Rocky Mountain Tick and the Brown Dog Tick. They all affect our pets externally through a bite and can transmit different types of diseases. For example, the black-legged tick can carry Lyme disease, which can be transmitted to humans and their pets. Tick prevention should be used from April to August. Bravecto or Nexgard is recommended.

Internal parasites such as roundworm, whipworm, hookworm, and tapeworm can be found year-round and survive in the environment for years. It is important to remember that if you have fleas, you likely have a tapeworm. Fleas carry tapeworms and pass the parasite through their bite. Puppies should receive deworming monthly until six months of age. After that, we recommend routine deworming every six months.

Heartworm is only a concern in the Okanogan Valley from May to October but can affect both our cats and dogs. Heartworm needs 2-3 weeks at a temperature above 27°C to mature in its host (the mosquito) before it becomes infectious. For this reason, heartworm is not a risk anywhere else in BC. If you are planning to travel to the interior, please talk to a vet about heartworm prevention.


Unlike in BC, fleas are a concern in Alberta from early spring to early October. The colder temperatures reduce the risk of fleas during the winter months.

Ticks in Alberta become active from early spring to August. In 2017, the Alberta government conducted a tick study to determine what ticks are in the area and what diseases they carry. The most common ticks are; American Dog Tick, Rocky Mountain Wood Tick, Winter Tick and Black Legged Tick. Some ticks can carry Lyme disease — your pet should be on a preventive medicine before travelling to this area. Nexgard or Bravecto would be recommended.

Roundworm and Tapeworm are very common in this province. Recent studies have shown there is a species of tapeworm that has become potentially lethal called Echinococcus multilocularis. It is more common in coyotes but is growing in population in our dogs. Routine deworming can prevent infections.

Heartworm is not a concern in Alberta due to the climate. As we learned above, the larvae need to incubate in a mosquito for 2-3 weeks at a constant temperature above 27°C.


As with every province, fleas are a concern. May to November all pets should be on flea prevention as even our indoor animals can get fleas. We carry them in from the outside world where they can jump from us to our pets.

Ticks are active from May to November as well. The most common ticks are American Dog Tick, Rocky Mountain Wood Tick and the Winter Tick. It is rare to see a Black Legged Tick, but it does happen. Prevention should be used when travelling to this area.

Roundworm, Hookworm and Tapeworm are a concern in this area. It should be noted that a problem with the potentially lethal tapeworm called Echinococcus multilocularis is also a concern in Saskatchewan. Be wary of animal droppings and always wash your hands.

Saskatchewan does not have heartworm. There have been a few positive cases over the years. Upon further investigating if was found the dogs travelled to a heartworm area, contracted the parasite and travelled home with it.


In Manitoba, fleas are present from April to November. All animals travelling to this province should be on flea treatment prior to and leaving this area.

Manitoba is home to the Black Legged Tick, American Dog Tick, Lone Star Tick and more recently Rocky Mountain Tick. The Lone Star Tick will bite humans as well and pass on a bacteria in their bite that can cause a red meat allergy in humans. Ticks are active from April to October.

Roundworm and Tapeworm are more common in the area. Regular deworming will reduce your pet’s risk of contamination. As always puppies should be dewormed monthly, adults every six months. Remember your pets could be infected but not show symptoms until the infection is quite bad.

Heartworm is a MAJOR concern in Manitoba. All pets travelling to this area should be on preventive medicine before and after they visit this province, and possibly be tested for heartworm.


As we travel east the flea seasons change — in Ontario, flea season is from June to October. If we remember from earlier, fleas equal tapeworm. Prevention is a must when travelling to Ontario.

Ticks season in Ontario is from April to November. The most common ticks are; the Black Legged Tick, American Dog Tick and more recently the Lone Star Tick. The first two are almost an epidemic in Ontario, while the lone star tick numbers are expected to rise over the coming years. Always wear protective clothing while out and check your pets daily if you are in this area. All ticks, in their various life stages, are visible to the naked eye.

Worms in Ontario are common; the most common is roundworm. Animals can pick them up from the environment without you even knowing it.10% of dogs infected with worms have whipworms. They are also picked up in the environment unnoticed. It’s best when travelling to be on preventive medicine for the whole trip. Various dewormers can be prescribed before your trip.


Fleas are most active May to October in Quebec. As previously mentioned, fleas carry tapeworms. Fleas also can carry a bacterium called Bartonella henselae. This bacterium causes an infection that will need antibiotics. Fleas can also cause dermatitis called Flea Allergy Dermatitis (FAD). It is caused by the saliva in the flea reacting with the immune system. FAD can also affect you and your pets.

In Quebec, there are many types of ticks. The Black Legged Tick is a concern as it carries Lyme disease which can be transmitted to humans and pets. This tick can be seen across Canada.

The Brown Dog Tick and Rocky Mountain tick carry Rocky Mountain spotted fever, and also cause tick paralysis. Simply remove the tick, and the paralysis will go away – but it is recommended to contact your veterinarian if you have concerns with any parasite.

The Lone Star tick has also been seen in Quebec, and their numbers are also expected to rise in the coming years. Any insect repellent with permethrin or DEET will aid in protecting you and your pet against ticks, although the best protection for your pet is preventative tick medication.

Heartworm is an epidemic in Quebec and all pets travelling to this area need to be on preventative medication before and after leaving this province. The heartworm season runs from June to November, and a simple monthly chew can protect your pet. Ask a vet today about preventative medications if you are planning to travel here.

As with the rest of Canada, roundworm is a risk in this area. It’s safe to say no matter where you are travelling, worms will be a concern.

Atlantic Provinces

All the Atlantic provinces share similar flea seasons. With them being so close together, it’s not a surprise that they all start flea season in May. In Prince Edward Island, Newfoundland and Labrador, flea season ends in October. While in Nova Scotia it ends in September and New Brunswick ends in November.

Ticks can be seen throughout the Atlantic Provinces, with the most common being the Black Legged Tick. Although there is a risk of Lyme disease in New Brunswick and Nova Scotia, ticks are not native to these provinces and have no known breeding population. Essentially, ticks in Newfoundland and Labrador are brought in by travelling pets and migrating animals.

The American Dog tick can be found in New Brunswick, Nova Scotia and PEI. The Brown dog tick can be found in PEI and are less common in New Brunswick. The Lone Star tick can be found in Nova Scotia and PEI.

Heartworm is not as common in these provinces, though the season runs from July to November in New Brunswick and Nova Scotia. French Heartworm is very similar to Heartworm. They both need an intermediate host and a definitive host. In the case of heartworm, it’s a mosquito, for French Heartworm it’s a slug or a snail. Both need the intermediate host to complete its life cycle. French Heartworm can only be found in Newfoundland and Labrador in Canada, at the moment.

Northern Canada

In the Yukon, Nunavut and Northwest Territories, fleas are active from April to September. Flea control should always be used during these months.

Ticks are not much of a concern for pets and humans this far up north. The most common tick is the winter tick and the rabbit. The winter tick mostly attaches to moose while the rabbit tick prefers rabbits. There have been siting’s of Rocky Mountain Wood Ticks and American Dog ticks, and these are believed to be brought back by pets travelling outside of these provinces.

Heartworm is not a concern in this area. However, there are species of tapeworm to be concerned with. T. gondii is also a big risk in some drinking waters and some meat. Always cook your meat to the proper temperatures.

If you have any questions, give us a call at 604-463-7100 for more information.