“Once in a while we get some large ones. When you cut it open, you see that the inside is much like the cream filling of a doughnut. It’s just disgusting. It’s offyellowy white, gooey, hideous stuff.”
– Ken Kingdon
Of the 28 elk killed this spring in Riding Mountain National Park, all have so far been found to be free of bovine tuberculosis.
A handful of local reporters was on hand to see the latest animal, a three-year-old pregnant cow elk from the west side of the park, hanging on a gambrel in the laboratory at Parks Canada’s maintenance compound as part of a media tour organized by Ken Kingdon, project co-ordinator for RMNP’s wildlife health program.
The animal had been captured earlier that morning by helicopter-borne specialists armed with a net gun, a sawed-off .30-06 modified to launch a net by channelling the blast of a blank cartridge through four steel tubes firing individual lead weights. Once trapped, it was then killed with a captive bolt gun, lifted out of the park via helicopter, and then transported to the lab in the back of a truck.
It had been caught the same way in February and fitted with a GPS-equipped radio collar after blood samples were taken. Because it was a “reactor,” meaning that the samples were found to have traces of TB antibodies, it was chosen for culling and post-mortem inspection.
So far this year, seven cow elk have been removed by Parks Canada officials from the western control zone, along with 21 taken by First Nations hunters around the park’s edges.
Culled, “non-reactor” animals are taken to an abbattoir in Sandy Lake, and the meat ground into hamburger and distributed to nearby First Nations or food banks. This elk, however, as a reactor, was deemed not fit for human consumption and would be buried in a landfill, said Kingdon.
Dr. Bob Keffen, a Canadian Food Inspection Agency veterinarian, was on hand to explain the post-mortem exam.
Telltale signs of TB infection are typically found in lymph nodes in the head and the thorax, and less commonly in other parts of the body, he said. Lymph nodes, which filter pathogens out of the blood, tend to concentrate TB bacteria and are therefore the best places to look.
“Over 90 per cent of the lesions are going to be found in the head or thorax,” said Keffen, who has extensive experience with wildlife capture and disease control in Africa.
In each post-mortem exam, researchers look for visible lesions, which are typically the size of a dime and filled with a granular or creamy substance. Samples are then sent to a lab in Ottawa for culturing and further inspection, and final results are returned within six weeks.
“Most of the lesions have been small,” added Kingdon. “Once in a while we get some large ones. When you cut it open, you see that the inside is much like the cream filling of a doughnut. It’s just disgusting. It’s off-yellowy white, gooey, hideous stuff.”
“It’s like a jam buster,” said Keffen. “It’s the texture of Philadelphia cream cheese.”
In cattle, however, TB-infected lymph nodes are gritty, due to the calcium deposits in the fluid. In particularly bad cases, the pustules may be quite large. Some animals in the early stages may show no outward signs of ill health, but in terminal stages, animals will typically cough frequently and show dramatic weight loss, he added.
Identifying TB-infected animals in the early stages, however, is notoriously difficult.
“Even if this thing comes back negative on the culture test, it doesn’t mean that it didn’t have TB. It’s just that we couldn’t find it,” said Kingdon.
That’s because current blood tests are less than perfect, added Keffen. For example, even though an animal’s immune system may be able to overwhelm a TB infection and kill off all of the pathogen, the remaining antibodies can still trigger a “postive” result of the reactor test.
For hunters, there is little risk of infection from butchering an infected animal, unless an infected lymph node is cut open and the fluid ingested somehow, say by smoking without first washing your hands.
“Generally, as long as the meat is well cooked, there’s no risk at all,” said Keffen.
The cow elk being examined was in good condition, judging from its layer of body fat. It was found, however, to have a small, round, brown necrotic cyst in its lung caused by a type of tapeworm which cycles back and forth between elk and canines such as wolves or coyotes. [email protected]