Chronic wasting disease affects mule deer, elk and white-tailed deer.
It has curtailed the transportation of these animals, and combined with
high feed prices, has had a devastating impact on alternative livestock
producers.
CWD was first discovered in the late 1960s in mule deer at a biological
research station in Colorado. These deer were wild animals captured
near the research station.
The first case of CWD in Canada was believed to be in a mule deer at
Read Also
Agriculture needs to prepare for government spending cuts
As government makes necessary cuts to spending, what can be reduced or restructured in the budgets for agriculture?
the Toronto zoo in the late 1970s that was obtained from the Denver
zoo. Western Canada saw its first case of CWD in a game ranched elk in
Saskatchewan in 1996, again from a U.S. imported animal. Since then,
CWD has been found in one farmed elk and one farmed white-tailed deer
in Alberta.
In Saskatchewan, it has been found in more than 40 farmed herds and
four wild mule deer.
The Canadian Food Inspection Agency has destroyed approximately 8,000
animals, mostly elk, in an attempt to curtail the spread of the
disease. Problems arise when deciding what is fair compensation to
producers whose animals are destroyed.
Clinical signs of the disease include inco-ordination, unthriftiness,
weight loss, excessive salivation and pneumonia. Many of these signs
are attributed to the lesions caused in the brains of affected
animals.
Diagnosis requires microscopic examination of the brain, but there is
ongoing research aimed at alternative methods, such as biopsy and blood
samples.
It is believed some animals may incubate the disease for as long as
three years without showing clinical signs. If an animal gets CWD, it
is 100 percent fatal.
Programs are in place requiring producers to submit the heads of all
elk and deer older than one year old that die or are slaughtered.
Hunters in Alberta and Saskatchewan are also requested to submit the
heads of animals killed in certain parts of the provinces.
It’s not known how the disease spreads. However, it does seem likely
that CWD existed in nature before the existence of modern game farming.
We do know it can spread between animals and from females to their
offspring. It seems to spread more easily in situations where there
are high densities of animals. It is believed that an environment can
become infected and transmit disease to healthy animals.
It is reasonable to assume bodily secretions such as saliva, urine and
feces can spread the disease. There has also been evidence to suggest
that there may be a genetic predisposition to the disease.
CWD is caused by a prion, a protein that has an altered three
dimensional configuration.
There is no evidence to suggest CWD can infect people or cattle.
However, since we do not yet fully understand this disease, we need to
be cautious. Any product from animals known to be infected with CWD is
not allowed to enter the human or animal food chain.
Numerous studies are under way to better help us understand the nature
of the disease. For example, why hasn’t this disease shown up in other
countries with a long history of alternative livestock production? The
truth is, we just don’t know.
Daryl Meger is a veterinarian and outdoors enthusiast in a mixed animal
practice in Westlock, Alta.
