Goats and sheep | Previous cases of goat scrapie involved previous contact
Progress on a national scrapie eradication program continues as the discovery of the disease in goats raises questions about infection route and goat susceptibility.
Seven new scrapie-infected premises have been identified in 2014. Six of them involve goats.
Prior to last December, the illness had only been found twice in Canadian goats, in 1975 and 2007, according to the Canadian Sheep Federation. In those cases, the animals involved had been in contact with sheep.
In December 2013, scrapie was identified in Ontario goats that hadn’t been commingled with sheep within the past five years. On one farm, 482 goats were slaughtered and tested.
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The Canadian Food Inspection Agency has not revealed how many of those were infected. It continues to investigate recent cases and complete trace-ins and trace-outs on the affected animals and flocks.
Scrapie is a fatal brain disease belonging to the same family as BSE in cattle and chronic wasting disease in cervids.
In sheep and goats, symptoms include itching, rubbing and wool pulling, which is the likely source behind its name.
Scrapie was first found in Canada in 1938 and is a reportable disease. However, it has been in European flocks since the 1700s and is considered endemic in many countries.
In the last six years, 4,075 Canadian animals have been destroyed in scrapie investigations and another 6,425 ordered slaughtered, according to CSF data. Scrapie can be confirmed only post-mortem and flock mates are usually killed to prevent spread.
Canadian sheep and goat organizations have set a goal to eradicate scrapie and have developed a strategic plan for doing so, said sheep federation executive director Corlena Patterson.
The University of Guelph has compiled prevalence estimates by using data from sample collection, farm submissions of sheep and goat heads and CFIA surveillance information.
They show scrapie could occur in one sheep among every 1,300 adults, a 0.08 prevalence. It could infect one goat in every 383 adults, a rate of 0.26 percent.
Patterson said goat figures are based on a much smaller sample size, so it’s a more cautious estimate than that for sheep.
“Until December, those results may have been questioned a little bit more critically because we had only, in the last 30 years, had two positive goat scrapie cases in Canada …” said Patterson.
“We’re being a little less critical of these numbers now.”
Scrapie is thought to spread among sheep and goats primarily through contact with birthing fluids from infected animals. It may also enter through lesions or exchange of body fluids.
Patterson said the eradication program’s goal is to sample 11,000 animals over a two-year period for a minimum of four years. That would meet international requirements leading to eventual designation as negligible risk.
“We’re hoping to do 1,050 goats and 4,450 sheep annually over the next four years, as a minimum,” she said.
Geraldine Goodman, president of the Canadian National Goat Federation, said her organization supports the goal of scrapie eradication in principle, although she said less is known about the disease in goats.
Research has revealed scrapie resistant genetics in sheep but the same has not occurred for goats.
As well, the goat industry doesn’t have a national identification program, making it difficult to trace individual animals suspected of having scrapie.
Producer awareness of disease is another issue, said Goodman.
Patterson echoed that view.
“It requires a commitment over time, so as we decrease the prevalence and as there are fewer and fewer cases, we see everybody’s interest starting to wane,” she said.
No country has ever eradicated scrapie within its borders and only a few are trying, with Canada and the United States among them.
The disease has become a trade barrier as countries move to prevent its spread.
