Symptoms of the disease include confusion, poor coordination and belligerence in the afflicted animal. There is no current diagnosis for BSE in live animals besides noting clinical symptoms. The only method of confirmation is to perform a biopsy on brain tissue once the animal has either died or been euthanized.
BSE is one of a group of Transmissible Spongiform Encephalopathies (TSE); others include Scrapies in sheep, Chronic Wasting Disease in elk and deer and Creutzfeldt-Jakob disease an inherited disease found in humans. BSE was linked to variant Creutzfeldt-Jakob disease (vCJD) a new form the disease during the early 1990s when the incidence of the disease doubled, and started occurring in people with no genetic predisposition to it.
BSE is transmitted to other cattle when protein (especially brain and spinal cord) or bone from an infected cow is rendered and added to cattle feed. It generally takes 4 years of incubation before the disease symptoms occur; during this time the animal is capable of transmitting the disease. When people eat processed meat from these infected cattle they can be infected with vCJD.
It wasn’t until 1997 that Canada banned the practice of feeding ruminants (animals with two stomachs such as cows, goats, sheep and deer) protein derived from other ruminants. In 2006, the CFIA announced that it would ban cattle tissues that are capable of transmitting this disease from all human food, animal feeds, pet feeds and fertilizers.
The disease was recognized in 1984 in England, unfortunately not before the UK had shipped BSE tainted cattle feed all over the world.
Since then, over 200,000 cattle have been killed due to BSE; the majority have been in Britain (over 160,000) other countries include France, Germany, Italy, Switzerland, Ireland, Canada, Portugal and Denmark.
Canada’s first incidence of BSE occurred in 1993 with a single case of a beef cow imported from England. It died while still on the farm and never entered the food chain. Both the carcass and the herd where it had come from were destroyed.
The first case of BSE in Canada of a cow born in Canada was found in Alberta in January 2003. Authorities believe that the cow contracted the disease after eating feed with contaminated bovine meat or bone meal approximately six years prior to it's slaughter (Canada instituted the ruminant food ban in 1997). The infected cow was considered to be sick with pneumonia at the time of slaughter and her carcass was condemned. As such it was determined to be unfit for human consumption and sent for rendering. Rendered protein from this cow was turned into poultry and dog food. (It is still common practice to feed protein from ruminants to hogs, poultry and pets).
The CFIA intentified the herds that the infected cow had spent time in contact with, as well as the natal herd. Over 2700 cattle in Canada that potentially came into contact with the infected cow, her offspring or shared feed with her were destroyed and tested for BSE . There have been no other incidences of disease.
A voluntary recall of the Champion Pet Food dog food was initiated to prevent discarded dog food made from this cow from mixing with ruminant feed. Luckily, there is no evidence that dogs can acquire BSE, nor that handling the food can transmit the disease.
Since this case, Canada has had 15 additional cattle succumb to this disease from farms in Alberta, British Columbia and Manitoba; there were 2 cases in 2005, 5 cases in 2006, 3 cases in 2007, 4 cases in 2008 and 1 so far in 2009. Over 3,000 cows, calves and bulls have been euthanized for testing as these animals came from the same natal herd or were calves born to infected cows; all tested negative for BSE.
In the current instance of BSE in Canada, the Canadian Food Inspection Agency (CFIA) announced on May 15, 2009 that a 6 year, 8 month old dairy cow has been confirmed to have the disease. This is Canada's 16th case of BSE to date. No part of the cow's body entered into the food system for either humans or animals. The CFIA is now tracing the path taken by this cow from its birth farm to the farm where the symptoms occurred.
For more information on the current BSE crisis in Canada check out the Canadian Food Inspection Agency's website BSE DISEASE INVESTIGATION IN WESTERN CANADA
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