Trichomoniasis has appeared in Manitoba and Alberta in recent weeks and may be a lingering after-effect of BSE.
There is no disease link between the two – one is a protein-clumping, brain-wasting disease and the other a microscopic parasite – but producer response to the financial effects of BSE may be making it possible for the tiny parasite to pick producers’ pockets.
Trichomoniasis is a venereal disease of cattle that was first described in France in 1888 and found in a Canadian herd in 1993.
“If you’re using a community pasture or grazing co-op that doesn’t follow a strict program to avoid trichomoniasis, then you might as well each be handing me $250 right now,” John Campbell told cattle producers attending a pasture management conference in Saskatoon June 15.
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“At least you’ll know where the money went.”
The veterinary instructor and research scientist from the Western College of Veterinary Medicine said he has had calls from Manitoba and Alberta in the past weeks about new outbreaks of an otherwise declining parasite infestation.
An infected cow’s immune system will attack the parasite as well as calf embryos, resulting in abortions that go unnoticed in the pasture. Cows present as open later in the summer for no apparent reason and will generally come back into heat.
In up to five percent of cases the calf will live up to 20 weeks before abortion. Occasionally in these cases the calf is not passed and decays in the uterus, which becomes filled with puss, mimicking pregnancy during a check.
The microscopic parasite is a particular problem in open range beef operations.
Campbell calculates that the infection costs producers $349 for each cow that has been exposed to a fully infected bull population. The cost is $226 per exposed cow if 40 percent of bulls are infected.
The parasite can only exist in the reproductive tracts of bulls and cows and bulls spread it during mating.
Cows can clear the infection if they are rested for four months or more, but bulls remain infected and must be culled.
Protection of the calf requires a two dose, modified-live vaccine that is given two to four weeks before breeding. The vaccine is also available in combination with Letospirosis and Vibrio vaccines.
Campbell said only the modified live vaccine will provide immunity for the calf.
Canada’s first outbreak occurred in 1993 in the Excel community pasture near Assiniboia, Sask., where it had devastating effects. The following season the producer members instituted a control plan that didn’t include vaccination and the following year achieved a 95 percent pregnancy rate.
The disease is controlled by ensuring that bulls are free from infection, which requires testing them three times because false negative tests can occur in 20 percent of cases. Producers can also start over with fresh bulls from herds known to be clean.
Cows are clean if they are virgin heifers or have a calf at side.
Bulls should never be moved between pastures during the breeding season and should be kept apart from cows out of season.
Campbell said last year’s outbreak near Lethbridge and the recent new cases in Manitoba and Alberta have likely been caused by producers who rebred open older cows in the last few years rather than culling them.
Vaccinations don’t stop the spread of the parasites, he added. Rather, they help prevent economic losses in the short term.
“BSE bites one more time,” he said.
“Producers kept the cows because there was no market for them, hoping to squeeze out a calf or two more. Now farmers are remembering why they used to cull those old girls.”
