EDMONTON - Another suspected case of mad cow disease has surfaced, this time in a young dairy cow on a farm near Edmonton.
The Canadian Food Inspection Agency is conducting tests to confirm whether the 50-month-old dairy cow, the youngest so far detected since the first case turned up in 2003, had bovine spongiform encephalopathy (BSE) when it died.
The cow, which was pregnant at the time, was a downer, which meant it couldn't stand without assistance, and it later died on the farm. A private veterinarian sent samples to the provincial laboratory, where screening tests could not rule out BSE, and samples were sent to the CFIA laboratory in Winnipeg.
If the case is confirmed, it would be the seventh in Canada and the fifth in Alberta. It's also the second Canadian case in the past week - tests confirmed BSE in a 15-year-old Manitoba cow on July 4.
The Alberta cow was born in 2002, five years after a ban on feeding cattle parts such as brains and organs to other ruminants - considered to pose the greatest threat of spreading BSE - went into effect in 1997
Dr. George Luterbach, senior veterinarian with the CFIA, said the fact that occasional cases are appearing is not surprising, and not a bad reflection on the effectiveness on the feed ban.
''I think in all countries that have had BSE in the world, they have found some cases after the feed ban. I guess the most logical explanation is there is some contamination that remained within their feed systems for a period of time.
''That said, Canada has tested 115,000 of the highest risk animals and we have had six cases over the last three-year period.''
The fact that this case has been detected shows the effectiveness of the BSE surveillance program, he said.
The farm and all of the animals on it have been quarantined, and CFIA officials are going through feed records to see if the affected cow was part of a ''cluster'' of cattle that ate feed that went through a mill in the Edmonton area. Luterbach would not say where the farm is located, and he did not know how many cattle are located there.
While feed containing cattle parts has been banned for cattle, feed for hogs and chickens still contains the parts, which are called specified risk materials (SRMs). A total ban on ruminant feed was approved last month, but won't go into effect for a year.
Dr. Gerald Ollis, chief veterinarian for Alberta Agriculture, said cross-contamination can occur when handling or transport systems for feed are used for both cattle and other types of feed.
''It only takes a milligram of contaminated feed to cause BSE in these animals,'' Ollis said. ''That was not known when the ruminant-to-ruminant feed ban was implemented in 1997.''
Rob McNabb, a senior manager with the Canadian Cattlemen's Association, said he didn't expect this to affect trade with the United States, which since the beginning of the year has allowed Canada to export cattle under 30 months.
The U.S. had imposed a temporary ban on Canadian cattle after the first BSE case showed up in 2003.