The tick factor
Dr. Katharina Lohmann: “For some reason, tick experts haven’t really looked at horses even though they’re a perfect subject.” Photo: Myrna MacDonald.
Like many Saskatchewan residents, I’ve have had to resign myself to dealing with ticks in recent years. Slowly but surely, ticks appear to be creeping into parts of the province that were previously (and blissfully) tick-free.
The first tick I ever encountered was flung clear across the room in horror (never to be seen again). But I’ve since become a pro at pulling them off of whatever animal they happen to be attached to and delivering a quick death between a boot heel and the cement barn floor.
I must confess I’ve actually developed a rather morbid fascination with the little bloodsucking arachnids – but I won’t go quite as far as Dr. Katharina Lohmann does.
“Once you get over the ‘ick factor,’ they’re really quite pretty,” says the large animal internal medicine specialist.
I am not convinced.
Lohmann, an associate professor in the Western College of Veterinary Medicine, is project director for a new study on tick-borne disease in Saskatchewan.
Funded by the WCVM’s Equine Health Research Fund, the project involves Lohmann as well as WCVM graduate student Dr. Gili Schvartz, veterinary pathologist Dr. Hilary Burgess and Dr. Tasha Epp, an epidemiologist at the veterinary college. The team also includes two tick experts: Dr. Neil Chilton of the University of Saskatchewan and Dr. David Pearl of the University of Guelph’s Ontario Veterinary College.
A WCVM-led research team begins a new study on tick-borne disease in Saskatchewan
The study focuses on testing for tick-borne bacteria Anaplasma phagocytophilum, which causes granulocytic anaplasmosis in horses and humans, and Borrelia burgdorferi, which causes Lyme disease. Both bacteria are carried in Canada primarily by Ixodes scapularis, commonly known as the blacklegged tick.
“For some reason, tick experts haven’t really looked at horses even though they’re a perfect subject – horses are large, live in areas where ticks are present and they tend to have close contact with humans,” says Lohmann.
The first part of the study will see a total of 300 blood samples collected and tested from labs located in Saskatchewan, Manitoba and Ontario. Lohmann and her colleagues estimate that two per cent of their samples may turn up positive for antibodies, indicating animals that have been exposed to either A. phagocytophilum or B. burgdorferi.
If positive results are found at this stage, the next step is to test those particular samples for the presence of the bacterial organisms themselves.
This is a preliminary study that will hopefully be followed up by more detailed research. “Since these particular diseases are not a big problem in Saskatchewan at the moment, now is a good time to establish a baseline for Saskatchewan as compared to other provinces,” says Lohmann. “Also, if tick populations are migrating north and west as they seem to be doing, we want to see where they’re at today so that we can better monitor changes in the future.”
To complement the blood sample testing, the WCVM is also conducting a “tick survey”: researchers are asking horse owners in Saskatchewan to collect and submit any ticks found on their horses throughout the year.
So far, the variety of tick species submitted to the survey includes Dermacentor albipictus (winter or moose tick), Dermacentor andersoni (Rocky Mountain wood tick) and Dermacentor variabilis (American dog tick).
Lohmann says the survey will continue at least until the end of 2013. “As far as we know, there is no Ixodes scapularis (blacklegged tick) population established in Saskatchewan, though they may be carried in from different areas of the country and from the U.S. by migrating birds.”
An “established population” means that all stages of the tick’s life cycle – eggs, larva, nymph and adult – are found in a particular area.
“If we do get any Ixodes ticks, we’ll test them for disease-causing bacteria. Dr. Chilton is testing other species of ticks for other purposes as well. We’ll also be able to identify their sex and what stage of the life cycle the ticks are at.”
In terms of anaplasmosis and Lyme disease, the level of concern at this point for horse owners is very low. There have been only three cases of anaplasmosis reported in horses in Canada, one of which was found in Saskatchewan in 2010 and is the case that prompted some of the questions in the study.
“Right now we want to see if anaplasmosis should be placed on the list of diseases that veterinarians in Saskatchewan can consider when making a diagnosis,” says Lohmann.
She adds that the symptoms of anaplasmosis – fever, low white blood cell count, jaundice, and suppressed appetite – are common among a range of equine diseases including swamp fever (equine infectious anemia).
“Bacterial titer levels will persist longer than we can see the organisms or detect them by PCR (polymerase chain reaction) assays, and a positive titer in connection with clinical signs is a strong indication of anaplasmosis,” says Lohmann.
So, should you find ticks on your horses this summer, Lohmann hopes that you’ll take the time to send them in to the WCVM’s tick survey. You’ll be helping out a good cause, and who knows – you might even develop a scientific appreciation for the tenacious little beasts. You might even call them . . . pretty?
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