Information compiled by Julia Michitsch B.Sc., M.Sc. (Zoology)

 Based on surveillance data from 2017, we have approximately 25 of the 900 known species of ticks in the world living with us in Ontario¹. The top 3 species of ticks identified were:  the black-legged, or deer tick (Ixodes scapularis), the American dog tick (Dermacenter variabilis) and the groundhog tick  (Ixodes cookei )¹.

 While each of these ticks can carry various disease-causing agents, the deer tick and it’s propensity for transmitting lyme disease to both dogs and humans makes it one of the top public health concerns in Ontario¹. In the early 1990’s, Long Point Provincial Park (located along the shore of Lake Erie to the west of Niagara) was the only area in Ontario where the threat of contracting lyme disease from a tick bite existed². Comparing the maps below, we can gain an appreciation of how fast the deer tick population, and hence the threat of disease, has spread across the province in only the last 3 years.

Researchers project that the deer tick population will continue to spread at a rate of approximately 46 km per year until 2022³. Climate change has been implicated as the most important factor influencing this spread, as the warmer temperatures allow the ticks to become established in areas where they could not before³. At this rate, the proportion of the human (and pet) population of Eastern Canada that will inhabit areas with established deer tick populations will increase from 18% in 2010 to over 80% by 2020³. 

 Lyme disease is caused by the bacteria Borrelia burgdorferi. Deer ticks pick up B. burgdorferi as newly hatched larvae in the spring/summer by feeding on the blood of small animals that carry the bacteria (mice, birds, squirrels)⁴. After spending the winter dormant in leaf litter, larvae mature into nymphs in the spring of their second year, and continue to mature through the summer until by fall they are adults, ready to mate and continue the lifecycle⁴. During both the nymph and adult stages, the tick will feed on the blood of larger animals (deer, dogs, humans)⁴. During the feeding process, the tick regurgitates enzymes from its gut that help to keep the blood from clotting⁵. As B. burgdorferi is also present in the gut of the tick, the process of regurgitation causes the bacteria to be transmitted to the new host along with these enzymes⁵. Transmission of B. burgdorferi from the tick to the new host takes a minimum of 48 hours – if the tick is removed prior to this time transmission will fail to occur⁵. Ticks are most active in the spring/summer months, but can remain active into the fall and winter as long as the temperature remains above 4°C ⁶.

Ninety percent of dogs that are infected with B. burgdorferi will not show any symptoms of lyme disease⁵. When symptoms (joint pain, fever) do occur it’s usually weeks to months after infection, and no bullseye rash will develop at the site of the tick bite, as it characteristically does in humans^1,5. The most serious complication of lyme disease in dogs is Lyme nephritis (kidney disease)⁵. This condition results from the dog’s immune system being constantly active in response to the B. burgdorferi infection leading to the production of antibody complexes that build-up in the kidneys over time, causing damage and reducing proper kidney function⁵. While cats can become infected with B. burgdorferi, their immune system seems to be better able to neutralize the infection before they develop any symptoms of lyme disease⁵. In fact, there have been zero reports to date of clinical disease in naturally infected cats⁵. 

 A quick blood test is all that is needed to determine whether a dog has been infected by B. burgdorferi. The blood is screened for the antibodies created by the dog’s immune system to proteins on the surface of the bacteria.

 Dogs will test positive for these antibodies within 3-5 weeks of infection, and can remain positive for over a year while the antibodies continue circulating in the bloodstream⁵. A positive test result does not therefore indicate an active infection, but does confirm that bacteria have been present in the bloodstream at some point in the past. Antibiotics are highly effective in treating lyme disease in dogs, with symptoms generally seen to improve within 48 of the start of the medication⁵. Dogs that test positive for infection may be required to have a urine test done in order to ensure that their kidneys are healthy and functioning properly. 

What can we do to keep our pets safe?

Lyme disease can best be prevented through a combination of tick management techniques and consultation with your veterinarian to determine the best tick prevention products for your pet. 

Tick Management: 

1. Ticks don’t like the sunlight, so keeping grass or brush around the house short will let light in and discourage ticks from inhabiting your yard. Remember that ticks also survive over the winter by hiding and laying their eggs in leaf litter where they are protected from the elements – cleaning up leaves before snow fall will reduce the likelihood of survival for the next generation of ticks. 
2. Avoid walking dogs in grassy or forested areas where ticks are known to reside.  
3. Check dogs for ticks every day. Remove any attached ticks with tweezers by grabbing the tick as close to the site of attachment as possible and pulling upwards in one steady and firm movement. Avoid squeezing the body of the tick with the tweezers, as this could facilitate infection by forcing the stomach contents (and potentially the bacteria) to the mouth of the attached tick. Place the tick in a container/sealed bag with rubbing alcohol after removal. Clean the bite area with rubbing alcohol, or soap and water. 

To help with surveillance efforts, you can bring ticks to your local Public Health office (https://www.niagararegion.ca/living/health_wellness/disease-prevent/ticks/remove-and-test.aspx) – This link provides details on how to package the tick, and where to take it in our area! 

As well, there is an ongoing project called the Canadian Pet Tick Survey organized by faculty at the Ontario Veterinary College. This is the largest systematic pet tick survey to date in Canada, and will provide necessary information on tick populations and the threat of disease across the country. If you discover a tick, please fill out the form at https://www.petsandticks.com/tick-submissions to help in their efforts!

Veterinary Care:

1. Have a yearly blood test done on your pet to check for exposure to lyme disease.
2. There are a variety of options when it comes to tick prevention products. Products can be administered orally or topically and should be given during the season when ticks are most active (May – November), although they can also be taken year round (remember, ticks are active any time of year as long as the temperature reaches 4°C). These products work to prevent lyme disease by stopping the ticks from attaching, and/or transmitting B. burgdorferi to your pet. 
3. There are vaccines available for lyme disease in dogs. These vaccines should be used in conjunction with tick prevention products and only on pets that have not already been exposed to B. burgdorferi (negative blood test). The vaccine will not prevent ticks from feeding on your pet, but will help to increase the speed of the immune response to the bacteria by having antibodies ready in the bloodstream to fight the infection when it occurs. 

It should be noted that ticks can carry a variety of disease-causing agents other than B. burgdorferi  (eg. Anaplasma spp. and Ehrlichia spp.). For this reason, having your pet on tick prevention products that stop the ticks from feeding and transmitting bacteria will protect them from these other diseases as well as lyme disease. 

If you have any questions about tick-borne diseases, or if you’d like to discuss prevention options for your pet, please give St. David’s Veterinary Clinic a call! 

References 

1. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Companion animals and tick-borne disease: A systematic review. Toronto, ON: Queen’s Printer for Ontario; 2017. Retrieved from: https://www.publichealthontario.ca/en/eRepository/Companion_Animals_Systematic_Review.pdf
2. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Vector-borne diseases 2015 summary report. Toronto, ON: Queen’s Printer for Ontario; 2016. Retrieved from: https://www.publichealthontario.ca/-/media/documents/vector-borne-diseases-2015.pdf?la=en
3. Leighton, P.A., Koffi, J.K., Pelcat, Y., Lindsay, L.R. and Ogden, N.H. (2012). Predicting the speed of tick invasion: an empirical model of range expansion for the Lyme disease vector Ixodes scapularis in Canada. J. Applied Ecol. 49: 457-464.
4. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Blacklegged tick life cycle. Toronto, ON: Queen’s Printer for Ontario; 2016. Retrieved from: https://www.publichealthontario.ca/-/media/documents/blacklegged-tick-lifecycle.pdf?la=en
5. Brooks, W. (2018). Lyme disease in dogs. Retrieved from: https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4952009
6. Duffy, D.C. and Campbell, S.R. 1994. Ambient air temperature as a predictor of activity of adult Ixodes scapularis (Acari: Ixodidae). 31(1): 178-80.