Mad Cow Disease

What scares people is words like fatal and epidemic. What scares people is trying to understand a complicated disease and a complicated supply chain for food. Before this disease was brought under control in Britain, people and pets died. With the first sick cow found in the United States, even local vegetarians are scurrying to determine how to protect their pets.

The naturally occurring route of transmission for Mad Cow Disease is eating infected tissue. To date, no dogs have been reported infected, but up to ninety cats were infected in Britain and one each in Switzerland, Norway, and Lichtenstein at the height of the European outbreak. In the US, one bovine case and no cases in pets (or people) have been reported.

Mad Cow Disease is a Family of Diseases

Mad Cow Disease, properly bovine spongiform encephalopathy (BSE), is one disease in a group called transmissible spongiform encephalopathies (TSE’s). TSE’s are transmitted through ingestion of abnormal protein particles, called prions. Prions are found primarily in the brain and spinal cord and in some glands, but only at the end of the disease incubation period.

The time between ingestion and development of disease signs is as much as five years in cattle and may be over ten years in humans; the disease once manifested is fatal.

TSE’s, species variants of Mad Cow Disease, include chronic wasting disease in elk and scrapie in sheep. A feline version has been reported in domestic cats in the UK and in large cat species living in zoos.

The disease has not been reported in classes of animals other than mammals, but is known to be transmitted among species of mammals. In one study, minks contracted their form of TSE from being fed TSE infected animal protein.

Humans or their pets can't acquire the prions by touching an infected animal, coming in contact with the manure of an infected animal or breathing air in a facility where sick animals are housed. Those traveling to countries where BSE has been reported need only avoid ingestion.

Species	Acronym	Disease Name	Occurrence
Humans	nv CJD	New variant CJD	110 cases UK, 1 France
Cattle	BSE	Bovine Spongiform Encephalopathy	651 Europe outside Britain in 2003, 1044 in Britain in 2002
Sheep		Scrapie	Widespread Europe, US, Middle East (notable absence in Australia, New Zealand)
Deer, Elk	CWD	Chronic Wasting Disease	up to 5% of hunter-harvested animals in 12 US states
Cats	FSE	Feline Spongiform Encephalopathy	90 cases UK

To understand one aspect of the risks, follow the prion. To contract the disease, you or your cat must ingest prions from an infected animal. Nervous system tissue, intestines and tonsils of infected animals is where the concentration of prions is highest.

Elizabeth Mumford, DVM, explains “The prion is very resistant to inactivation. Chemicals and heating do not affect it. When infected animal tissues are rendered and included in feed for susceptible animals, the prion is recycled in the population. The amount of circulating prion increases with each cycle.”

Prions, then, can be found in infected meat such as game animals processed at home or meat from commercial packing houses. For humans or pets, the most likely source is from food—specifically meat, although supplements may also be suspect because brain and glands from cattle are sometimes are used in supplements. This concern was highlighted in the July 27, 2000, issue of the New England Journal of Medicine. Author Scott A. Norton, M.D., M.P.H, contended that supplement labels often obscure the fact that the products contain animal tissues.

There is no documentation of human cases being acquired through routes other than ingestion, including blood transfusion.

The Pet Food Institute represents the manufacturers of 95 percent of the total dog and cat food tonnage produced in the United States. PFI explains, “Pet food labeling and advertising claims are regulated by the USDA, FDA, and the Federal Trade Commission (FTC). All pet food plants are subject to inspection. IAMS, a member of the Pet Food Institute, is a maker of dog and cat foods, including the IAMS and Eukanuba brands. Kurt Iverson, Manager of External Relations for the IAMS Corporation reports that IAMS goes to great lengths to ensure their product is safe for your pet. In addition to acquiring the lamb which is a principal protein in their diets from New Zealand and Australia, the corporation uses no beef in dry foods. In the foods using beef, IAMS uses parts known not to carry the protein and avoids use of carrier spots. Carrier spots have been designated by the USDA as central nervous system, tonsils and intestine.

Member companies of the PFI want to allay the fears consumers have. Mr. Iverson reminds pet guardians of the importance of reading labels on their pet foods. He also suggests calling your pet food supplier consumer hotline. Iverson says, “There has never been a case where a dog has had the disease. The UK cat cases have been linked to a raw food diet.”

Elizabeth Mumford, DVM, one of SAFOSO’s experts in animal health and food safety, says, “There does not seem to be a risk for dogs. Even in the UK where the exposure to infective material was greatest, no cases of TSE were seen in any canine species.” She explains there is a risk of Feline Spongiform Encephalopathy (FSE) for cats that have eaten BSE-infective material.

The risk for small mammals including mice, rats, hamsters, gerbils, guinea pigs and rabbits is unknown. “Experimentally, certain rodent species can be infected, but there have been no reports of small rodent pets or pests with TSE.”

Mumford cautions, “There is certainly a risk for ruminants kept as pets, though the extent of the risk for small ruminants such as sheep and goats and camelids [alpacas, llamas] is unknown. There have been no reports of TSE in horses and there does not seem to be a risk for birds.”

Other experts add that the risk of a given individual eating tainted meat can't be calculated. The Centers for Disease Control and Prevention (CDC) estimates the risk in the United Kingdom is one case for every 10 billion servings of beef and beef products. The risk is unlikely to be any higher in other countries. (The odds of being killed by space debris are 1 in 5 billion.)

Dr. Jeff Judkins, a member of the American Holistic and the Oregon Veterinary Medical Associations feeds his own dogs organic chicken. Judkins advises, “Any way you look at it, Mad Cow Disease is rare. The feeding practices that spawned this disease in Britain are banned here. This is not something you should worry about. Feed good quality dog food, or feed organic food. If you want to feed organic food, read Ian Billinghurst on the biologically appropriate raw food diets.”

The US Humane Society reiterates there is no evidence of a disease form that affects dogs. The Feline Spongiform Encephalopathy appeared in approximately 100 cats in Europe that were believed fed "butcher scraps,” not commercial pet food. To date, there have been no confirmed cases of FSE in the United States.

The Humane Society suggests pet companions look at labels for specific protein sources. “An ingredient such as "meat" or "meat meal" or "animal by-products" doesn't tell you what animal or animal part was used. Consumers should look for "chicken", "lamb meal," or other specifically named animal sources as well as parts like "chicken liver," "turkey heart,"...”

Regulations are one way the US Department of Agriculture (USDA) is attempting to keep people safe and keep them eating beef. New rules eliminate the use of cows that are too injured or sick to stand on their own for human consumption. Slaughtered animals inspected for the disease may not be processed until the results of the tests are known, and slaughterhouse techniques that can mix brain or spinal cord tissue with muscle are prohibited.

The Humane Society explains prior to the ban on using downer cattle “4-D (dead, dying, diseased or down) meats [were] sent to rendering facilities, along with other offal (animal products considered unfit for human consumption) from factory farms. They [were] then boiled, melted, or otherwise processed to become tallow, meal, or other ingredients to be used in edible and inedible products, including pet foods. “

The “stable to table” concept is familiar and accepted there. The Federation of Veterinarians of Europe (FVE) explains that socioeconomic changes have taken food off family farms and into intensive environments; in fact, globalization has made animal trade international. FVE contends that food safety requires the “development of schemes enabling full traceability of food products from the production place to the consumer…”

Quality livestock feed and animal welfare leads to healthy livestock. Healthy livestock slaughtered safely and hygienic meat production leads to safe food entering the human and pet food supply chains.

At each stage of the process, regulations apply. Regulations did not prevent the beginning of “Mad Cow," and many do not see regulations as the solution. The Missoulian ran an editorial which states that the discovery of one mad cow demonstrated “measures that the government and beef industry believed were sufficient to keep the United States free of this disease are demonstrably inadequate.” The question pet guardians need to consider is how much of a risk this is to their animal.

Organic meats, grain and grass fed on small farms, are available to consumers at a higher price than the “industrial scale” produced meats. Some pet owners, including Dr. Judkins, buy organic materials and produce their own “ground” foods. Could anyone guarantee a grain fed cow will not develop BSE? Can anyone guarantee the sun will rise tomorrow? Think relative risk.

Research advances in prion related disease are made every day. For example, North Carolina State University scientists have discovered an enzyme and conditions that can degrade prion particles. The next step in this testing is for decontaminating meat processing equipment and in converting infectious laboratory mice to noninfectious mice. Advances undoubtedly will lead to information that seems contradictory. If the news confuses you, reorient yourself by communicating with your pet food supplier and your veterinarian.

• Review pet diet labels
• Call pet diet consumer line
• Call your veterinarian
• Discontinue feeding raw beef byproducts

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