Update on Parasites and Your Dog

The Bowmanville Veterinary Clinic’s mission statement is “Excellence in Care for Pets and Their Families”. One of the ways we provide continued excellence in care is through client education.  (Pictured left is a Lone Star Tick)

We recently were invited to attend a conference on the changing face of parasites in Canada and felt we needed to update you on these changes. The guest speaker at this meeting was Dr. Michael Dryden from
KansasStateUniversity. He is a world renowned parasitologist and has made it his life’s work to follow parasite trends around the world. He gives unbiased information on parasite products that he recommends. Dr. Dryden noted that by 2050 with our current rate of global warming our climate here in Southern Ontario is predicted to resemble that of Tennessee.

There are a number of parasitic diseases that are now on the increase in
Southern Ontario, including our area. These diseases include internal parasites such as roundworm, hookworm, whipworm, heartworm, giardia etc. and external parasites such as ticks, fleas and mosquitoes.

Many of the increases we are seeing can be attributed to climate change. There is truly a benefit to the cold Canadian winters we have experienced in the past, and that is that many parasites cannot survive severe cold. With our trend to warmer winters we do not get the “winter kill” that used to happen. Three years ago we followed Dr. Dryden’s recommendations and implemented a 12 month parasite program as our gold standard for dogs and outdoor cats. This recommendation is now stronger than ever, and our product recommendation continues to be Sentinel for dogs and Revolution for cats, administered once monthly, year round.

Sentinel is an excellent product for heartworm, flea, roundworm, hookworm and whipworm prevention. Other internal parasites such as Giardia or Coccidia must be diagnosed by fecal exam.

Fleas are now present through out most of the year and the best way to prevent an infestation in your home is to use a product such as Sentinel that has an insect growth regulator (IGR). This IGR does not allow the eggs or larva to hatch in your home in Dr. Dryden’s opinion Sentinel is the best and most effective flea prevention available on the market for dogs.. Any stray or hitch-hiker adult fleas can be killed by using a product called Capstar if necessary, luckily this is very rare.

Heartworm disease has increased in incidence in Canada. As you may know heartworm disease is spread by mosquitoes. With our mild winters we are seeing mosquitoes much earlier than before. This is another reason to administer year round Sentinel. A recent study indicates that in the last ten years, positive heartworm cases have risen 68%. In the past most dogs that contracted heartworm disease had traveled into areas where heartworm had a higher incidence i.e. the southern U.S. In this study over 50% of the dogs had never left their immediate area. This is significant because it means that there are heartworm positive dogs where you live that can be spreading heartworm disease to your dogs. The wild dog population i.e. coyotes can also harbor heartworms and may be spreading the disease.

The most significant change in parasites is in the tick population. We are seeing “more ticks in more places.”  There are a number of species of ticks. The most common ones seen here are the Black Legged tick and the Brown dog tick. There have also been more infrequent sightings of the American Dog tick and the Texas Lone Star tick. It is not the tick itself that causes disease but the bacteria that the tick may contain. The tick acts as a vector for these bacteria. That’s why these diseases are called vector borne diseases.

Most of us have heard of Lyme disease by now. The number of Lyme disease cases within Canada have risen the most in our area i.e. Southern
Ontario. The Black Legged tick that carries the Lyme bacteria can also cause Anaplasmosis disease. The most common tick we see at Bowmanville Veterinary Clinic is the Brown Dog tick which is a vector for Ehrlichia disease.
RockyMountain Spotted Fever and a number of other rare but very serious diseases can be transmitted by the American Dog tick and the Texas Lone Star tick.

Ticks thrive in areas that have a tree canopy as they do not like sunlight. They also live in areas that have leaf litter to help them survive colder weather. Deciduous woods are perfect for this. The white tailed deer is an important part of the Black Legged tick’s life cycle, therefore areas where there is an established deer population have more concerns for Lyme disease. Adult ticks look for or “quest” for hosts from the blades of grass near these areas. They then drop onto the host and attach to the skin.

Ticks have long been an area of concern in the warmer climates of the U.S but their range is expanding and we are seeing higher densities of ticks which are leading to more tick encounters.

There are several reasons for this: 

• Reforestation i.e. more areas for ticks to thrive


• Wild-life conservation- there are now an estimated 30 million White Tailed Deer in North America – these deer are an important part of the life cycle for the Black Legged Tick that carries Lyme disease.


• Climate change- warmer winters


• Decreased pesticide use


• Increased human contact with natural areas i.e. suburbs, landscaping, dog walking in parks


• Migratory birds- A study completed in August 2011 found that millions of Lyme disease vector ticks are dispersed annually by song birds across Canada. The study also found that 48% of the inmature ticks found on these birds carried the bacteria that causes Lyme disease. This is significant as it means that humans and animals can contract Lyme disease locally with out any history of travel. Moreover it also means your dog (and you!) do not have to walk in areas where White Tailed Deer exist in order to contract the disease.

We are fortunate to have a vaccine to protect high risk dogs from Lyme disease. There is currently no vaccine for Ehrlichia or Anaplasmosis, but there are other ways to help protect your dog. We recommend a yearly blood test called the 4DX test. This test screens for heartworm disease, Lyme, Ehrlichia and Anaplasmosis. 

Early detection of these diseases is important as treatment is most successful in the early stages of the disease. 

The Preventic collar is also recommended for high risk dogs. These collars were recommended for spring and fall in the past when ticks were in higher numbers but the increased incidence of ticks may indicate that all year round is a good idea.

It is important to elevate tick control in your yard.

Gold Standard for Parasite control in high risk dogs

• Current Physical exam- must have been seen within the year to dispense prescription product.


• Fecal Analysis yearly


• 4DX yearly along with wellness testing to screen for organ disease


• Sentinel 12 month


• Preventic collar


• Lyme vaccine

What to do if you find a tick on your dog

• Bring in to the clinic for removal


• Have 4DX test done one month and four months after the is tick found


• Elevate tick control i.e. Preventic collar, Lyme vaccine.

Dr. Dryden feels we do need to be more aware of the potential for increased exposure to parasites. The above recommendations can help you protect your dog and yourself against possible serious and life threaten