Dawson Creek Veterinary Clinic
238-116 Ave
Dawson Creek, BC V1G 3C8
(250) 782-1080
Dr. Zoë Ross, Dr. Andrew Hodges
Dr. Mike Ross, Dr. Cathy Saker
Dr. Heather Weaver, Dr. Sandy Jameson
Ticks Bothering Your Animals?
Many of you may be finding ticks on your animals this time of year and probably have many questions about these creepy crawly critters!
The species of tick you are finding on your animals at this time of year is commonly known as the Winter Tick or the Moose Tick. The proper name for them is Dermacentor apbipictus. They can vary from reddish- brown to gray-brown and have 8 legs as adults. They are most often found on wildlife including moose, deer, elk and bison but cattle and horses that share pasture with these wild species can become infected. They will feed on coyotes and wolves (and dogs and cats) but these are not their primary hosts.
These ticks are quite distinctive from other types of ticks because they
- reach their adult stage during the late winter and early spring and they are a one host tick.
- The larval stage of the ticks attach themselves to the host (including your horses or cattle) in the fall and will remain on this same host until they reach their adult stage and take a blood meal.
- They will then drop off their host and lay eggs in the environment (in leaf and grass litter on the ground).
- These eggs hatch in August and September and the larval form climb up vegetation and wait for an appropriate host to brush up against them where they catch a ride on a warm fuzzy body for the winter.
- The larvae feed and change into nymphs in October and November
- and then the nymphs feed and change to adults between January and March.
- Generally the females feed and fall off into the environment by May and lay their eggs in June. An adult female can lay up to 5000 eggs (YUCK!!!)
- The tick population generally is at a peak after a mild spring and winter when there is not a lot of snow, allowing for a lot of eggs to be successfully laid in the leaf litter and hatch in the fall.
- The population is also related to the moose population in the area, when the moose numbers are at their greatest, so are the tick numbers!
The nymphs and larvae are difficult to see without the aid of a microscope, while the adults are very obvious at 5-7mm long, sometimes reaching twice this size when they are engorged (have had a blood meal). Engorged females are very large and are the only type of ticks found feeding at this time of year in Canada. We have also done some diagnostics on ticks found on clients horses at this time of year and have confirmed them to be “winter ticks”. Generally these ticks stay on one animal but occasionally may move from host to host if animals are kept in close contact.
Horses and cattle with light to moderate infestations do not generally have any clinical signs. Occasionally they may be pruritic (itchy) around the bite sites and there may be a slight swelling at these sites. Animals with heavy infestations (usually moose) can become very itchy and irritated by the ticks. Biting, chewing, licking, rubbing and scratching can make moose lose their hair or break their hair at the roots (moose hair is white at the base), which make the moose look white or worse!
Treatment can be difficult. If the tick is actively feeding, oral ivermectin dewormers are effective but if they are not feeding they will have no effect. Carbaryl is the only product in Canada approved for the treatment of winter ticks in horses and cattle. (The product we are carrying at the Dawson Creek Veterinary Clinic is called Dusting Powder and is made by Dominion). There are also pyrethrin/pyrethroid products that may also work.
Although winter ticks may occasionally be found on people and may bite people, they have not been found to carry any agents that may infect people such as Lyme disease or Rocky Mountain Spotted Fever (which can be carried by other species of ticks).
If you have any other questions or concerns regarding these unwelcome visitors or any other questions for us, feel free to stop in or call the Dawson Creek Veterinary Clinic to talk to one of our veterinarians.