Our team continues to be here for you and your cherished pets. We are OPEN and are now able to provide a wide range of services. To learn more about the changes we have implemented in response to COVID-19 and what to expect during your next visit, click here.

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Heartworm Facts and Myths

Heartworm is a preventable but potentially fatal disease caused by parasitic worms infesting the arteries of the lungs, heart, and surrounding blood vessels of dogs, and other mammal species. All it takes is one bite from an infected mosquito, that’s right this is not a parasite that your pet picks up from sniffing the ground, eating dirt or poop, this parasite hangs out in a mosquito just waiting to bite your pet. Anyone that owns a pet can easily prevent this disease with a little knowledge and the help of your veterinarian at McLean’s Animal Hospital.

Every year in our Scarborough pet hospital we are seeing more cases of Heartworm.

Here are some facts and some myths about this potentially fatal disease:

Myth #1: Heartworm is not in Canada or Ontario.

Fact: Heartworm has increased a full 60% over numbers in 2002 the main hotspots in Canada are southern Ontario, southern Manitoba and Quebec. Researchers speculate that the increase of heartworm positive cases in Canada is due to dogs coming up from the US to be adopted here in Canada, these dogs specifically after hurricane Katrina helped to increase the numbers in Canada significantly.

Myth#2: Indoor dogs and cats are not at risk for Heartworm.

Fact: Since this disease is passed through mosquito bites, where ever they can go they can bite, all it takes is one bite from an infected mosquito to infect your dog, so yes that little buzzy mosquito that you can hear but can’t see when you are sleeping, very likely its biting your dog.

Myth#3: Heartworm is easy to treat, I’ll just take my chances.

Fact: By the time that your pet starts to show the signs of heartworm infestation it is often too late. Initially there are no symptoms, but once the disease has progressed a little the load on the lungs and heart become too much most pets will develop a cough and exercise intolerance. Once it has progressed to the severe level your veterinarian will be able to hear abnormal lung sounds, your pet will retain fluids and can actually lose consciousness from lack of oxygen to the brain.

Myth #4: It’s really expensive for prevention and Heartworm testing.

Fact: At McLeans our heartworm testing is $55.00 and prevention can be had for as little as $6.00/month. We treat from June 1st to November 1st which will prevent Heartworm in your pet. Alternatively treating Heartworm is well over $2500, and could result in the death of your pet.

As always if you have questions about Heartworm or would like more information about keeping your pet safe from this preventable disease please give us a call in the clinic at 416-752-5114. There is always someone there to answer any questions or concerns you may have, we can all work together to prevent Heartworm and keep our pets safe.


by Marion Cummings, CCR



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Last updated: July 28, 2020

Dear Clients,

With recent changes to restrictions on businesses, we are pleased to advise that effective May 19, 2020 some restrictions on veterinary practices have been lifted. Based on these changes, below are some important updates to our operating policies.


This includes vaccines, wellness exams, blood work, heartworm testing, spays and neuters, dental services, and more!



If you wish to connect with a veterinarian via message, phone or video, visit our website and follow the "Online Consultation" link.


We are OPEN with the following hours:

- Monday: 8:00 am - 7:00 pm
- Tuesday: 10:00 am - 8:00 pm
- Wednesday: 10:00 am - 7:00 pm
- Thursday: 8:00 am - 7:00 pm
- Friday: 10:00 am - 7:00 pm
- Saturday: 9:00 am - 2:00 pm
- Sunday: CLOSED


Have you welcomed a new furry family member to your home? We’d love to meet them! Visit our Must Know New Pet Owner Information page for useful resources and helpful recommendations for new pet owners.

Thank you for your patience and understanding and we look forward to seeing you and your furry family members again!

- Your dedicated team at McLean Animal Hospital