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FAQs about Mad Cow Disease in the U.S.

The Humane Society of the United States

Since the outbreak of mad cow disease in Washington state in 2003, and the U.S. Department of Agriculture's swift implementation of an interim ban on allowing downed (nonambulatory) animals into the human food supply, concerned consumers and animal advocates alike have contacted The HSUS, trying to seek further information. Below are some frequently asked questions and our responses.

Mad Cows in the United States

Dec. 2003: Downed BSE-infected cow reported in Washington
June 2005: Downed BSE-infected cow in Texas
March 2006: Downed BSE-infected cow in Alabama

  1. What is BSE, commonly referred to as mad cow disease?

    BSE is a transmissible spongiform encephalopathy (TSE) affecting bovines, commonly known as cattle. Specifically, BSE stands for bovine spongiform encephalopathy. As its name indicates, it causes sponge-like microscopic changes in the brains of cattle, and produces behavior, such as staggering, that gives rise to the name mad cow disease. BSE results when a prion protein becomes abnormally folded. In cattle, these misshapen prions are most concentrated in the brain, spinal cord, and the small intestine.

    The disease is believed to have originated in Britain, where it was discovered in 1986 and increased rapidly, peaking in 1992 at more than 3,000 cases per month. It is not contagious. Healthy cattle are infected with BSE when they are given feed supplemented with BSE-infected animal products. The practice of feeding cattle protein to cattle was banned in Britain in 1988. Feeding certain high-risk cow parts to cattle was banned in the United States in 1997 by the U.S. Food and Drug Administration (FDA), although that ban has been weakly enforced and plagued with non-compliance problems, according to two studies by the U.S. General Accounting Office and the FDA's own data made public in October 2003.

    In 1996, evidence surfaced that BSE is transmissible to humans. Eating infected material is the likely cause of a new variant of Creutzfeldt-Jakob disease (vCJD). A fatal degenerative human brain disease with no known cure, vCJD can cause memory loss, depression, spasms, incapacitation, and an inability to communicate, as well as premature death. Approximately 150 people are known to have died from vCJD to date, mostly in the United Kingdom. One person in the United States has contracted this disease to date; she resided in the United Kingdom during the major outbreak of BSE there.

  2. What has the USDA banned?

    On December 30, 2003, the U.S. Department of Agriculture announced a series of steps designed to address concerns about the safety of U.S. beef. The USDA's announcement came after a single Holstein cow, reportedly a downer who could not stand, tested positive for BSE infection—and after the agency was pushed to take immediate action by The HSUS and others.

    The USDA has taken the following steps:

    • Immediately banned downer cattle from being used in human food. Unlike pending legislation, the administrative ban does not cover species other than cows. Nor does it prohibit the use of downed cows in edible products intended for animals other than humans, such as pet food and feed for chickens, pigs, and other animals.
    • Announced intentions to stop the practice of labeling animals as "inspected and passed" and allowing their meat to be sold while BSE test results are still pending.
    • Banned certain high-risk tissue from cattle older than 30 months of age, such as the skull, brain, and eyes—as well as the small intestines from cattle of any age—for use in human food. These slaughterhouse by-products will still be allowed in the feed of animals other than cattle.
    • Prohibited certain high-risk tissue from being included in meat processed using the Advanced Meat Recovery (AMR) system. AMR is a method of extracting meat close to the bone.
    • Banned air-injected stunning guns, which can contaminate meat with high-risk tissue. Most federally inspected plants in the United States stopped using air-injected stunning devices prior to this ruling. That technology has been replaced by captive bolt stun guns and non-penetrating captive bolt guns, which are designed to knock animals unconscious and are still allowed under USDA rules.
    • Prohibited Mechanically Separated meat from entering the human food supply.

    To learn more about this announcement, read the USDA's statement on the downer ban and the other BSE control measures announced on December 30, 2003.

  3. What is a "downer"?

    According to statements by USDA officials, the administrative ban on the use of downers for human food applies to all nonambulatory disabled cattle—that is, any cows who are unable to stand or walk, regardless of the reason. This is important because the industry has argued that animals unable to walk due to injury, rather than illness, pose no threat to the food supply. The USDA apparently recognized that it is very difficult for inspectors to correctly discern the reason an animal is nonambulatory. In fact, the Washington state BSE case involved a cow whose records indicated she was unable to walk due to "acute calving complications" (injuries while giving birth), not because of an underlying illness.

    The USDA's ban on downer cattle in the human food supply will encourage improved care and handling to prevent cows from becoming downers in the first place. Because downers are no longer allowed in human food, they are now worth less money than they were before the ban.

    As Temple Grandin, Ph.D.—advisor to the American Meat Institute and others in the meat industry—long ago explained in Meat & Poultry magazine, "Ninety percent of all downers are preventable." For those cows who still become downed, the ban means producers will have little reason to transport them live to slaughter plants because the animals cannot be sold for human food. Rendering plants do not need—nor are most equipped to handle—animals arriving alive. So the ban will minimize the inhumane practices of dragging, kicking, and pushing downers will bulldozers.

    The USDA's ban does not currently require humane euthanasia for animals as soon as they become downed. The HSUS will continue pressing to require that.

  4. Are downer cows the only animals affected by BSE-type diseases?

    No, many animals are affected by TSEs, including the following related diseases that have been detected so far in different species:

    • Cattle and certain wildlife (eland, kudu, pumas, lions, and tigers)—bovine spongiform encephalopathy (BSE), discovered 1986.
    • Pigs—via experimental inoculation, 1989, with evidence suggesting that porcine spongiform encephalopathy can hide as a subclinical infection
    • Deer and elk—Chronic Wasting Disease (CWD), 1967.
    • Domestic cats—Feline Spongiform Encephalopathy (FSE), 1990 (see question 8 below).
    • Humans—Creutzfeldt-Jakob Disease (CJD), 1921, and variant Creutzfeldt-Jakob Disease (vCJD), 1996.
    • Mink—Transmissible Mink Encephalopathy (TME), 1947.
    • Sheep and goats—Scrapie, 1700s.

    Furthermore, TSEs can remain in an animal for months or years before showing any symptoms of the disease. Thus, besides downers, seemingly healthy looking animals may be carriers of TSEs. Currently, there are no reliable tests to detect whether a live animal has TSE. There are TSE tests that can detect prions in dead animals. However, these tests are only accurate if there are a high number of irregularly folded prions in the animal.

  5. What are the regulations for livestock feed, and are animal products being fed to other animals?

    The FDA (the federal agency responsible for regulating production of feed for birds including chickens and turkeys, livestock, and other animals) established a ban in 1997 on the use of most animal protein in feed for cattle and other ruminants. However, this ban does not include cattle blood fed to infant calves in milk replacer. In Britain, two people died of vCJD after receiving blood transfusions from an infected meat-eating donor. In the United States, essentially anyone who has been in Britain for more than six months is not allowed to donate blood on the chance that he or she may have vCJD. Yet FDA continues to allow calves to be fed blood from other cows who may be infected with BSE.

    The use of mammalian protein in the manufacture of feed for pigs and birds, including chickens and turkeys, continues to be allowed because it is thought those species are resistant to contracting a TSE. However, as long as feed is manufactured using materials at high risk for containing dangerous prions, there are concerns because of:

    • Noncompliance with the FDA ban, including misfeeding on the farm and the mislabeling of prohibited feed;
    • Accidental contamination during manufacture (e.g., equipment used for ruminant feed that was previously used to manufacture feed for pigs or poultry);
    • Poultry manure which is sometimes fed to cattle. It could contain spilled poultry feed tainted with TSE-contaminated animal products. Furthermore, it is not yet known whether manure from poultry could harbor active prions;
    • Potentially contaminated manure used as fertilizer.

  6. How do animals and humans become infected with TSEs?

    Cattle typically develop the disease after eating a prepared feed mix that contains meat or rendered animal products from animals harboring a TSE. Ruminant animals, such as cattle, are true herbivores and do not naturally consume animal products at all. The practice of "feeding cattle back to cattle" was designed by industrial agriculture; animals are fed protein sources from other rendered animals to increase their rate of weight-gain and milk production. Unlike bacteria, molds and viruses, prions are not adequately destroyed by heat sterilization, domestic bleach, or formaldehyde sterilization, and can survive even incineration at temperatures hot enough to melt lead.

    If TSE-infected animals are not intercepted, their contaminated parts such as brain or spinal cord tissue can still enter the human food supply, even under the new USDA ban.

    Currently, after killing an animal, slaughterhouses use a saw to cut the carcass along the spinal column, and this process has been shown to disperse small pieces of the spinal cord on surrounding meat. It has also been shown that current decontamination methods are ineffective in removing this high-risk tissue from the carcass. Inspection of live animals before slaughter is intended to prevent sick and diseased cattle from entering the food supply. However, cattle with BSE may not show symptoms of the disease, especially if the animal is younger than two years of age—the common age for most beef cattle.

  7. Is it safe to eat beef?

    Scientific understanding of BSE is not complete, so this is a difficult question to answer. In the United States beef is likely safer than poultry products and seafood, two of the riskiest categories in terms of foodborne illness, which affects an estimated 76 million people in the United States and kills thousands of Americans every year. The HSUS encourages consumers to practice the 3 Rs: refining, reducing or replacing animal products.

    By refining, we can choose to purchase meat and other animal products from those producers who are engaged in programs such as Certified Humane that promote greater welfare for their animals. We can reduce the amount of meat and animal products we consume. And, we can replace animal products with vegetarian alternatives.

  8. Are my companion animals at risk from BSE-infected pet food?

    Although there is no scientific evidence or confirmed cases of dogs contracting a form of TSE, there have been confirmed cases of Feline Spongiform Encephalopathy in approximately 100 cats in Europe. To date, there have been no confirmed cases of FSE in the United States.

    Currently, downed animals, as well as other condemned meat, can be used in pet foods. These meats, known as the 4-D—dead, dying, diseased or down—meats, are sent to rendering facilities, along with other offal (animal products considered unfit for human consumption) from factory farms. They are then boiled, melted, or otherwise processed to become tallow, meal, or other ingredients to be used in edible and inedible products, including pet foods.

    There are precautions you can take to help ensure that your companion animals are safe. First, look for specific protein sources. An ingredient such as "meat," "meat meal," or "animal by-products" doesn't tell you what animal or animal part was used. A specific source will help you identify what animal or animal part the protein was derived from, so look for "chicken," "lamb meal," or other specifically named animal sources as well as parts like "chicken liver," "turkey heart," etc.

    Next, you can call the manufacturer of the food and ask about its animal ingredients. Find out its policy on BSE and ask what the company is doing to protect your pet. The company's contact information should be on the food container. And finally, remember that your cat is a carnivore and will not flourish on an unsupplemented vegetarian diet. A raw diet or table scraps may also put your pet at risk and cause an imbalance of nutrients, vitamins, and minerals if not fed under the express direction of a veterinarian experienced with raw food diets.

  9. What further measures and actions are needed to protect animals and reduce the risk of BSE?

    • We must be watchful for any efforts in Congress to weaken the USDA's administrative ban on downers in the food supply, such as attempting a narrower definition of downers to exclude animals who supposedly become nonambulatory because of injury.

    • Every cow over 20 months of age should be tested for BSE before being used in food for humans or pets, and restrictions should be put in place to ensure that high-risk tissue from rendered cows does not end up in human or pet food.

    • The FDA must strengthen enforcement of its feed ban and close loopholes to prohibit blood, manure, slaughterhouse waste, and other animal products from being used as feed for any farm animal.

    • All persons in the animal industry should be trained on how to prevent animals from becoming downers.

    • All individual animals should be traceable from birth, using non-invasive, tamper-resistant bio-metric techniques, such as retinal vascular eye scans.

    • Country of origin labels should be incorporated into all animal products and products containing animal by-products. This would provide consumers with more information about where their food is coming from and a way to check for adequate animal welfare and food safety policies.


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