What is heartworm?
Heartworms are parasites that infect dogs and other animals.
The worms make their home in the heart, where they block blood
flow, damage the lungs, and cause other health problems. The
disease is often fatal in heavily-infested dogs.
How does a dog get heartworm?
Heartworm is transmitted by mosquitoes. When carrier mosquitoes
bite a dog, they inject tiny heartworm larvae into the dog's
bloodstream. These microscopic larvae eventually settle in the
dog's heart, where they can grow to be 30 cm (12 inches) long.
When the adult heartworms produce new larvae, the larvae circulate
in the dog's blood and are picked up by biting mosquitoes. The
carrier mosquito bites a new victim and the cycle begins again.
What are the symptoms of heartworm
disease?
There is a wide spectrum of symptoms, depending on how many
worms are living in the dog's heart. Dogs with only a few worms
may carry them for years without showing any symptoms. Dogs
with many worms usually develop serious heart, lung, liver and
kidney problems, with symptoms such as weight loss, coughing,
fever, poor haircoat, and inability to tolerate exercise. Dogs
with heavy infestations will usually die unless the disease
is treated.
Is there a test for heartworm?
If your veterinarian feels your dog is at risk for heartworm,
he or she will probably recommend a simple blood test to rule
out the disease. If the initial test is positive, further tests
may be recommended to confirm that your dog is infested. It
is very important to confirm the dog's heartworm status before
starting preventive medication or treatment.
Do we have heartworm in Canada?
Yes. Heartworm occurs in warmer regions, where summer temperatures
are high enough for the worm larvae to survive inside the carrier
mosquitoes. The high-risk areas in Canada are southern Ontario,
southern Quebec Manitoba, and the Okanagan in British Columbia.
Heartworm is also found in most states in the US.
Although it is not absolutely certain, it appears that heartworms
are unable to survive at prevailing temperatures in Alberta
and Saskatchewan. A few cases are diagnosed in these provinces
every year, but to date they have all been dogs that have visited
or lived in heartworm risk areas.
How do I protect my dog from heartworm?
With heartworm, an ounce of prevention is truly worth a pound
of cure. The disease can easily be prevented with inexpensive
monthly medication prescribed by your veterinarian. Heartworm disease can be fatal. Further, treatment of
full-blown heartworm disease is costly, time-consuming,
hazardous, and not always successful.
If you are traveling outside Alberta with your pet, talk to
your veterinarian about heartworm before you leave. Your veterinarian
will identify heartworm risk areas and prescribe appropriate
preventive medication, if needed.
Can my cat get heartworm?
Although dogs are the natural hosts for heartworm, cats will
occasionally become infested as well. Preventive medication
is therefore recommended for cats traveling to high-risk areas
during the mosquito season. Heartworm tests and medications specifically
for cats have recently become available - talk to your veterinarian.
