• BSE has been diagnosed in more than one hundred British cats (Marsh, 1996).
• BSE and other strains of BSE-like transmissible encephalophies can also be encountered by animals which may consume pet foods including mink, hamsters, mice, ostriches, and zoological animals.
• BSE has not been reported in dogs.
• The obligatory responsibility of the Pet Food Industry includes the protection of pets and pet owners from various forms of zoonotic prion diseases. Since normal transmission of prion-associated diseases is associated with food and feed intake and the disease is always lethal, the prevention of BSE in America's companion animals should be relatively straightforward.
• BSE appears to be caused by a single strain of prions, similar to, but distinct from those strains of natural or experimental scrapie of sheep, but analogous to the new prion diseases of cats (Collinge, et al, 1995).
• BSE is particularly important within the pet industry since ingredients such as sheep with scrapie and cattle with Downer's Disease may be used in pet foods.
• BSE has subsequently been diagnosed in 19 captive animals of eight species at or from eight zoological collections in the British Isles. The family Bovidae include one nyala, four eland, six greater kudu, one gemsbok, one oryx, plus members of the cat family including four cheetah, and one puma. Swine have spongiform encephalopathy, also (Bradley, 1993).
• Encephalopathy in ostriches has also been diagnosed in two German zoos (Kirkwood and Cunningham, 1994). All of the carnivores had been fed parts of cattle carcasses judged unfit for human consumption.
• Transmissible mink encephalopathy (TME) was determined to be similar to that naturally occurring scrapie-like spongiform encephalopathy described in mink by Dr. G.R. Hartsough in 1965 at several mink and pet food symposia. Based on current knowledge used to evaluate the feeding practices of many mink farmers with the extensive use of animals dying of undiagnosed causes, road-kill, offal, and 4-D animal products, the early detection of TME in mink should not be surprising. Similar conditions, including scrapie in domestic sheep and goats, were described prior to the 1980's and also included chronic wasting disease in mule deer and Rocky Mountain elk (Irwin, 1991).

Sources of "lamb and lamb by-product meal" for U.S. pet foods:

• The U.S. production of ovine by-product meal was estimated in 1995 to be 4.500 pounds per working day or just enough to produce five tons of "lamb" and rice dog food daily.
• Since dogs have not been found to have any form of BSE, the relegation of that by-product meal entirely to dog foods can be considered relatively safe if pet-food plant sanitation is adequate to prevent contamination into cat foods.
• If the remainder of the "lamb by-product meal" and lamb (meat) is obtained from countries which have only scrapie-free sheep, then that lamb can be used in cat foods with relative safety.
• For each pet producer's integrity, it is almost obligatory to obtain a guarantee by the supplier that each shipment of lamb or lamb by-product meal used in cat foods is supplied entirely from those countries free of sheep and goat scrapie. Some American companies have followed that safety practice. For example, IAMS, and perhaps other companies, own sheep slaughter facilities in New Zealand and Australia supplying their entire "lamb" needs thus insuring their ingredients are from scrapie-free sources.
• The Voluntary Flock Certification Program promulgated in 1992 ostensibly regulates intrastate movement of sheep and monitors flocks in the 9 million population sheep industry. This program's effectiveness is not known and is similar to the early volunteer ban on the shipment of British BSE infected cattle to slaughter.
  
• The American pet food industry has the enviable opportunity and responsibility to maintain the superior quality control with ingredients used for pet foods and continue to avoid or minimize problems associated with the array of spongiform encephalopathies which have been encountered in many other parts of the world.

Minimizing BSE-like Exposure of America's Pets and Decreasing Manufacturer Liability

• Restrict supplies of U.S. lamb and lamb by-product meal to dog foods
• Use imported lamb and lamb by-products for cat foods
• Avoid rendered products containing mink carcasses or offal
• Avoid rendered proteins containing dogs and cats from veterinary clinics and humane societies
• Maintain clean, dust-free, storage for rendered products
• Purchase animal protein ingredients from highly reputable suppliers
• List complete ingredient description on each mamallian protein purchase order
• Thoroughly inspect each received shipment for delivery invoice correctness
• Maintain exceptionally careful and thorough records of all animal protein transactions
• Use superior quality control to insure products ordered are products received
• Retain a sample of each mammalian protein source in long-term storage, perhaps for years for complaint control purposes

References

• Bradley, R. 1996. The research programme on transmissible spongiform encephalopathies in Britain with special reference to bovine spongiform encephalopathy. Dev. Biol. Scand. 80: 157-170.
• Brown, P; P.P. Liberski, A. Wolff, and D.C. Gajdusek. 1990. Resistance of scrapie infectivity to steam autoclaving after formaldehyde fixation and limited survival after ashing at 360°C: Practical and theoretical implications. J. Infectious Diseases 161:467-472.
• Brown, P., R.G. Rohwer, E.M. Green and D.C. Gajdusek. (1982) Effect of chemicals, heat, and histopathologic processing on high-infectivity hamster-adapted scrapie virus. J. Infectious Diseases 145 (1982) 683-687.
• Coles, P. First Vache Folle. Nature 350(6313) 4, 1991.
• Collinge, J; M.S. Palmer, K.C. Sidle, A.F. Hill, et. al. 1995. Nature 378(6559) 759, and Nature 378(6559) 761-762.
• Elliott, I., 1996. Link assumed between BSE and human neurological disease. Feedstuffs 68(13) 1 +4
• Groschup, M.H., and E. Pfaff. 1993. Studies on a series-specific epitope in murine, ovine, and bovine prion protein. J. Gen. Virol. 74 (pt.7) 1451-6.
• Hartsough, G.R., and D. Burger. 1965. J. Inf. Dis. 115, 387
• Irwin, T. 1991. Disease strikes Canada's elk ranches. New Scientist (1964) 14, (13 April).
• Kimberlin, R.H., 1993. Bovine spongiform encephalopathy: an appraisal of the current epidemic in the United Kingdom. Intervirology 35:1-40
• Kirkwood, J.K: A.A. Cunningham 1994. Epidemiological observations on spongiform encephalopathies in captive wild animals in the British Isles. Vet. Res. 135(13) 296-303.
• Marsh, R.F., 1991. Symposium Bovine Spongiform Encephalopathy and Scrapie: Pathobiology and Public Health Policy. University of Illinois, March 14.
• Marsh, R. F. 1993. Bovine spongiform encephalopathy: a new disease of cattle? Arch. Virol. Suppl. 7, 255-259.
• Marsh, F.R. and R.A. Bessen. 1993, Epidemiologic and experimental studies on transmissible mink encephalopathy. Dev. Biol. Scand. 80; 111-118.
• Marsh, R.F., 1996x, Personal communication, April 5.
• Middleton, D.J and R.M. Barlow 1993. Failure to transmit bovine spongiform encephalopathy to mice by feeding them with extraneural tissues of affected cattle. Vet. Rec. 132(22) 545-547.
• Prusiner, S.B., 1994, Annal Review Microbiol 43: 655-686.
• Taylor, D.M.; H. Fraser, I McConnell, D.A. Brown, et al. (1994) Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie. Arch. Virol. 139(3-4) 313-326.