Mad Cow

John Maas: Symptoms and issues in tracking cattle

John Maas

John Maas is a UC Davis Cooperative Extension veterinarian and a national expert on veterinary care for food animals, particularly beef cattle. He also has been an active cattle rancher for 35 years. In mid-December, the USDA sent Maas to the United Kingdom and Europe to review the mad cow disease/bovine spongiform encephalopathy surveillance systems there. Maas can discuss U.S. cattle-tracking methods and disease-surveillance programs from regulatory, industry and university perspectives.

Q. What are the symptoms of BSE in cows? Can veterinarians diagnose BSE when they see symptoms on the ranch?

A. Veterinarians cannot diagnose BSE just from a physical examination. The disease can mimic many other common diseases such as ketosis, hypomagnesemia (grass tetany), Listeriosis, rabies, injury and milk fever (hypocalcemia), just to name a few.

Q. Is there a danger that veterinarians and ranchers can catch BSE from working with cows?

A. No. The disease cannot be passed to humans by contact with an affected animal. This is different than with rabies, which can be passed to people working with an infected cow. We do have rabies in California from time to time, so our veterinarians and producers are very well trained on how to handle these types of cases when they occur.

Q. Can other livestock and horses catch BSE from an infected
cow?

A. No. Again, the disease is not transmitted by direct contact.

Q. What type of trace-back system is being considered for cattle, and what are the challenges of establishing such a system?

A. It has been suggested that a national food-animal identification system is needed. For cattle, it's believed that this would be particularly useful in controlling not only BSE but also tuberculosis, foot-and-mouth disease and brucellosis. For example, a cow-calf producer would start by putting a standardized, approved ear tag or computerized implant or tag on each calf or cow before it could leave the ranch. At the auction or other point of sale, the identification information would be transferred to the new owner and entered into a database. If the animal were transferred to other owners at any point before it reaches the feedlot or slaughterhouse, the information would be updated to reflect the sale.

This type of system seems very logical, but actually raises many issues that would have to be resolved by both government and industry before it could be implemented. First of all, who will maintain and manage this massive database of information? Furthermore, if this is a publicly managed database, is this public information that anyone can access? And this brings up all kinds of new liability issues. I'm not saying that a trace-back system wouldn't work, but it would have to be developed with extreme care and with the involvement of both government and industry to avoid creating more problems than it solves.

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