Steven S. Nicholson, Merrill, Thomas A. | 10/4/2004 4:26:06 AM
Reports concerning Bovine Spongiform Encephalopathy have raised a lot of questions.
The disease, also known as mad cow disease or BSE, for short, is relatively unknown to the public, and catching just snippets of news reports sometimes leads to misunderstandings, experts say.
To clear up some of the misconceptions or questions, here are some of the questions being raised and the answers provided this week (Jan. 5-9) by LSU AgCenter veterinarian Dr. Steve Nicholson:
Could BSE spread across the country and infect my cattle? No, BSE is not a contagious disease. It is not transmitted animal-to-animal by contact.
How do cows contract the disease? By eating feed containing tissues from a cow that had the disease. To prevent this problem, the practice of feeding rendered ruminant byproducts to cattle and other ruminants was banned in 1997 in the USA and Canada.
How long does it take for BSE to develop in a cow? Two to eight years. The mean is said to be four to five years.
Do cows with BSE produce calves that have BSE? If maternal transmission occurs, it apparently is rare.
What is the "30-month rule" in the United Kingdom? In the UK, cattle younger than 30 months are being used for meat, because BSE does not appear to develop in exposed animals until later than 30 months of age.
Why aren’t all cattle in the United States tested for BSE when they are sent to slaughter? That procedure is being used in the UK – where BSE was first recognized in 1986 and where more than 186,000 cattle have tested positive. That action was necessary because of the extent of the problem in that country. On the other hand, before the Dec. 9, 2003, case, there had never been any indication that BSE exists in the United States. And there still is no reason to believe that BSE is affecting or will affect significant numbers of U.S. cattle.
What has been done in the United States to see if BSE is present in our cattle? More than 58,000 cattle brains have been examined for evidence of BSE. These were from cattle that exhibited signs or symptoms of brain or spinal cord illness. None were positive for BSE until the recent case in December 2003 in the cow that apparently contracted the disease as a calf in Canada.
What steps had our government taken to reduce the chances of BSE becoming a problem in our cattle? Importation of ruminant livestock from the UK was banned in 1989. Other countries where BSE has been found have been added to the list since then. In October 1997, feeding of tissues from ruminant animals to cattle and other ruminants (the primary method of transmission) was banned in the United States and Canada.
My dogs and cats eat pet foods containing cattle and sheep protein byproducts. Are they at risk for BSE? There is no indication that BSE occurs in dogs – although BSE has been diagnosed in more than 100 British cats. The pet food industry in the United States has taken steps to protect itself against financial liability by adopting measures to keep ruminant byproduct protein from areas where BSE exists out of pet food products.
What about zoo animals? BSE-like disease was seen in ruminants in the United Kingdom, large cats in the United Kingdom and nonhuman primates in France. Feed containing rendered ruminant byproducts from diseased cattle is thought to have been the source in these cases.
What is the purpose of the quarantines placed on at least three U.S. cattle herds that received Canadian cattle? It prevents movement of animals to slaughter or to other locations. This allows time for investigators to identify and trace animals back to herds of origin. Investigators are especially interested in finding all cattle that were in the same herd as the diseased animal when it was a calf.