It was originally believed that the prion protein thought to be responsible for the disease would not cross from one species to another, but it has made the jump through the consumption of contaminated feed and adapted to new hosts (1, 2). In 1985, this principle was demonstrated when an outbreak of a spongiform disease occurred as a result of having fed BSE downer cattle to mink. (46, 48, 64) In a 1990 paper for the dairy publication, Hoard's Dairyman, the University of Wisconsin-Madison veterinarian Richard Marsh and Minnesota animal health consultant William Wustenberg announced that the evidence from the mink outbreak suggested a mad cow-like disease "is present but not recognized in the U.S." In fact, mink outbreaks traced to downer-cattle as feed were known as far back as the early 1960s. (51)
Experiments have shown that BSE can be transmitted to many animals, including goats, sheep, mice, monkeys, pigs, and mink (53).
- The deaths of domestic cats and a wide variety of other animals in Britain were associated with their diet of rendered animal feed containing BSE-contaminated cows. As of January 2000, around 100 domestic cats had died from FSE, the feline form of the disease, in that country (1). These were just the deaths that were confirmed, but there were most likely many more (63). John Bower, president of the British Veterinary Association said, “Vets are presented with cats showing nervous disorders like this one every day. Some can be treated, some can’t and have to be destroyed. But in 90% of cases when they do have to be put to sleep the owners don’t want us to carry out a post mortem
- In zoos, outbreaks of spongiform diseases among big cats, primates, antelope, and other species, have been associated with the feeding of BSE-infected material. One study in 2001 identified 82 cases having occurred in zoos (2).
- Research has confirmed it is possible to transmit scrapie (the sheep version of the disease) to cattle (51). Sheep scrapie could be transmitted to cattle and it could then be passed from cattle-to-cattle (47).
- BSE from contaminated cattle can infect mink (67).
- Material from BSE-contaminated cows also caused disease in macaque monkeys, which displayed brain characteristics of the new variant CJD (72).
- Brains from a mink that had died from eating downer cattle were injected into mink, ferrets, monkeys, hampsters, mice, and Holstein calves (65). Every species except the mice developed a TSE, including the cows. A critical observation from this experiment was that the infected cattle did not display the typical clinical symptoms of British-style BSE [i.e., the cows did not act "mad"[; rather, the symptoms were more like those seen in ‘downer cow syndrome’ (53, 66). Ultimately, the conclusion was reached that the U.S. has its own native version of Mad Cow Disease, the symptoms of which are not as extreme as those in the British outbreak, but can be observed in its ‘downer cattle.
- Paul Brown, medical director for the U.S. Public Health Service, believes that pigs and poultry could be harboring BSE and passing it on to humans, adding that pigs are especially sensitive to the disease. (30) Two epidemiological studies found pork to be a dietary risk factor in Creutzfeldt-Jakob Disease (the human form) (78, 79). In late 1978, Dr. Masuo Doi, a veterinarian with the Food Safety and Quality Service, studied a disorder in pigs that had arrived at a packing plant in Albany, N.Y. from several Midwestern states. The USDA's pathologist reported that the damage in the pig's brain was similar to the damage observed in the brains of sheep afflicted with scrapie (77). The conclusion was that a TSE disease has already infected pigs (53, 80). However, when the FDA finally drafted a rule that would ban the fortifying of animal feeds with "any Mammalian tissue," the FDA played a taxonomical shell game by arbitrarily removing pigs from the class of ‘Mammalia.’ They declared that a pig is NOT a mammal!
