Keep watch for rabies

An Ontario government veterinarian is warning those who are moving livestock, inside the province and out, to monitor rabies outbreaks.


The outbreaks in Hamilton and western Ontario might be far from provincial borders, but “there’s always a risk of translocation, and it can be within livestock,” said Maureen Anderson, lead veterinarian in the health and welfare branch of the Ontario Ministry of Agriculture. 


“We have had cases reported to us for example where a beef cow gets off trailer at a slaughter plant and is showing neurologic signs.”


Incidents of rabies confirmed in animals jumped to 288 in Ontario in 2016. By way of comparison, Canadian Food Inspection Agency statistics show a total of 87 cases of rabies in Canada’s four western provinces in 2016. 


In March, western provinces totalled only nine confirmed rabies cases compared to Ontario’s 35. 


Anderson said the greatest number of incidents have occurred in Hamilton, where 305 cases have been confirmed to date. Most cases are in raccoons and skunks, but it has also been found in a fox, two cats and a llama. 


The Hamilton outbreak has been traced to a strain active 500 kilometres away in southeastern New York state. 


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An animal carrying the disease “probably hopped a truck,” Anderson said.


She attributed the outbreak to persistence of the disease in local wildlife populations at levels too low to be detected.


Vaccinating livestock in high-risk areas can be a good idea, she said.


“Vaccine costs money and it takes effort to get animals vaccinated, and that’s why it always has to be a conversation between the producer and their veterinarian.” 


Livestock and pets can form a bridge for the disease to pass from wildlife to people, she added, so vaccination of these animals also protects the people who handle them.


The Ontario Ministry of Natural Resources and Forestry is responsibile for controlling the disease in wildlife.


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Opportunities to drop an oral vaccine in bait by air are limited, so the bait must be dropped by hand. The ministry has baited a 50-km zone around all the positive cases to help prevent spread and no cases have appeared outside of the control zone, Anderson said.


Steven Crawford, a large animal veterinarian with Newry Veterinary Service near Atwood, dealt with two confirmed cases in dairy cows on one farm — one late last fall and the other mid-March.


He suspects rabies in another animal’s death on the same farm last July although post-mortem results were inconclusive.


“The only finding that was of real clinical significance was that the animal was extremely dehydrated,“ he said, noting one signal of rabies is a fear of water.


It’s common to have delays be-tween instances of the disease occurring on the same farm or local area, he said. 


The virus must reach an animal’s brain to trigger the disease. The infection travels through the nervous system, and the amount of time it takes to reach the brain depends on where the animal was bitten. 


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Crawford said he is not aware of any instances of cattle transmitting the virus to people.