The veterinarians also claim the facility -- part of the USDA and known as the National Veterinary Services Laboratories -- has refused to release testing results to them and has been so secretive some suspect it is covering up additional mad cow cases.
Distrust of the NVSL is so widespread among USDA veterinarians and meat inspectors it limits mad cow disease surveillance "tremendously," said a veterinarian with more than 25 years of experience with the agency.
The veterinarian, who requested anonymity because he feared repercussions, said many agency inspectors do not consider it worth the trouble to inspect cows closely for signs of mad cow disease or to send brain samples to the NVSL because there is little chance the lab will issue a positive result, even if the cow is infected.
In some instances, when USDA veterinarian inspectors have sent brains from cows they suspected of having mad cow disease, NVSL staff members have said they did not receive enough brain tissue or that they received the wrong part of the brain, the veterinarian explained.
The inspectors insisted they sent in the entire brain, "but that is the end of the story," he added.
The USDA's official stance is that the U.S. beef supply is free of mad cow disease, or bovine spongiform encephlopathy, but the veterinarian said, "Most agency veterinarians know mad cow is prevalent and epidemic (in U.S. herds). We're not talking about one or two cases."
An international panel of mad cow experts, commissioned by the USDA to review the agency's response to the animal that tested positive for mad cow in Washington state in December, reached a similar conclusion in a report they issued last week.
The panel said it was "probable" additional infected cows had been imported from Canada and Europe, some of which had been turned into cow feed and indigenously infected U.S. herds.
The concern is humans can contract a fatal brain disease known as variant Creutzfeldt-Jakob disease from eating meat contaminated with the agent that causes mad cow disease.
"The USDA has such a cohesive relationship with industry" that it wants to protect the $70 billion beef industry more than consumers, the veterinarian said, and noted colleagues with whom he is in close contact think the agency's mad cow surveillance program "is a laughing matter."
When asked to comment for this story, USDA spokesman Jim Rogers requested UPI forward its questions about NVSL via e-mail. Although UPI complied with this request, the agency did not respond.
Stanley Hall, who owns a deer herd in Almond, Wis., has been embroiled in a legal battle with the USDA since 2002 over whether one of his deer tested positive for chronic-wasting disease. CWD is the deer equivalent of mad cow disease and is detected using the same test.
In September 2002 NVSL said one of Hall's deer tested positive for CWD. Hall, who had retained some of the deer brain, then had it tested by Beth Williams, a veterinarian and renowned CWD expert at the University of Wyoming in Laramie.
Williams concluded in her report that abnormal prions, the agent thought to cause CWD, were "not detected." Williams noted, however, that the sample consisted only of the caudal medulla oblongata region of the brain and not the preferred obex region, meaning early infection with chronic wasting disease could not be ruled out.
Based on the conflicting results, and because he knew the brain sample tested by Williams originated from his deer, Hall suspected the sample tested by the USDA did not come from his deer, but rather from some other animal.
USDA officials, however, refused to release their sample for DNA analysis, even though Hall has offered to pay the $80 test fee himself. Hall said he thinks the USDA has refused to conduct a DNA test "because it won't match" his deer.
The USDA has not responded for more than a year to a request filed by Hall's attorney, Gary Drier in Stevens Point, Wis., under the Freedom of Information Act, asking for additional information about the tissue sample in question and how it was processed. Under federal law, the agency is required to respond to a FOIA request within 30 days.
"There's something dirty going on in that lab in Ames," Hall said. Based on the NVSL results on his deer, Wisconsin's Department of Agriculture, Trade and Consumer Protection ordered Hall to kill his herd of 100-plus deer, an order he is appealing.
Dr. Lester Friedlander, a former USDA veterinarian, agreed with Hall and said, "There's definitely issues" with the validity of NVSL test results.
Friedlander, who was a decorated employee during his 10 years with the agency from 1985 to 1995, recounted an experience he had in 1991 when he sent a tissue sample from a sick cow to NVSL and a separate sample from the same cow to a USDA lab in Athens, Ga. The test results conflicted, with NVSL reporting one type of cancer and the Athens lab reporting a different type.
In another incident, Friedlander said he was taking photographs of cow brains in the early 1990s before he sent them to NVSL for mad cow testing.
"Some of the brains were really suspicious, but the test results (from NVSL) always came back negative," he said, and noted he doubted the results. "But when you only have one lab (doing all the testing) who's going to listen to your story?"
The anonymous USDA veterinarian said NVSL often refuses to provide test results, even to the inspector who initially requested the test. NVSL's refusal to send lab reports "has been routine for the last two or three years," he said. "By this time, we don't trust Ames."
In a 1997 case, with which the veterinarian was familiar, a brain sample from a cow suspected of having a brain disorder was sent to NVSL. The diagnosis came back as a disease known as Progressive Ataxia. This seems implausible, he said, because in the annals of veterinary medicine the disorder has only been seen in the Charolais and Simmental cattle breeds -- and only rarely at that -- and the cow in question was a brown and white Hereford.
Without an outside lab also conducting tests, "we are not going to have a very independent analysis. It's very easy to control the results," he said, and noted a pathologist at NVSL told him lab staff often do not have access to all the test results from one animal.
The international panel's report advised the USDA to decentralize its mad cow testing program and permit other labs around the country to conduct tests and help facilitate the rapid testing of suspect animals.
Friedlander said decentralizing the testing would be a good start toward restoring confidence in the results. Right now, he added, "Nobody is actually questioning the lab" or conducting confirmation tests of the results.
Steve Mitchell is UPI's medical correspondent. E-mail email@example.com
Notable deaths of 2014 [PHOTOS]