California Department of Food and Agriculture

Bovine Spongiform Encephalopathy (BSE)

BSE, widely known as “Mad Cow Disease,” is a fatal disease of cattle first recognized in the United Kingdom (UK) in 1986. Most research suggests an abnormal protein, known as a prion, causes this progressive neurological disorder. BSE spreads in cattle primarily through ingestion of protein meal rendered from tissues of an infected animal. Cattle infected with BSE take 2 to 8 years before showing signs of disease, which include changes in temperament such as nervousness or disorientation, and progressive incoordination. Scientific evidence supports a link between exposure to the disease agent that causes BSE in cattle and the new human disease, variant Creutzfeldt–Jakob (vCJD) disease.

There are two strains of BSE. The typical strain, which was linked to outbreaks in the UK and Canada, is known to be preventable through the elimination of BSE-contaminated feed. Food and Drug Administration regulations have prohibited the inclusion of mammalian protein in feed for cattle and other ruminants since 1997. The rule was strengthened in 2008 by prohibiting high-risk tissue materials of cattle origin from use in all animal feed. The typical strain of BSE has never been identified in U.S. born cattle. The atypical strain of BSE appears to represent a sporadic disease that may occur spontaneously in any cattle population.

blue wedge BSE in North America (+/-)

The current hypothesis is that BSE entered North America through cattle imported from the UK during the 1980s before the disease was recognized. There were 182 UK cattle imported directly into Canada and 300 imported in the U.S. from 1982 to 1990. Following their arrival into North America, the UK imports became members of Canada or U.S. national cattle herds. Since the 1980s, both the U.S. and Canada have implemented preventative measures to ensure cattle and human health. Due to the effective surveillance and mitigation measures in place in the U.S., the World Organization for Animal health (OIE) categorized the U.S. as negligible BSE risk in 2013.

To date, there have been twenty-four Bovine Spongiform Encephalopathy (BSE) cases diagnosed in North America – 20 cases in Canada, and 4 cases in the United States. For more information, see BSE in North America.

  • On April 24, 2012, the National Veterinary Services Laboratory in Ames, Iowa confirmed that a routine surveillance sample obtained from a 10-year old Holstein cow carcass at a rendering plant in the Central Valley of California was positive for the atypical strain of Bovine Spongiform Encephalopathy (BSE). No part of this carcass entered the human or animal food chain.
  • On March 13, 2006, BSE was confirmed in a non–ambulatory, approximately 10–year old crossbred beef cow sampled on a farm in Alabama by a private veterinarian. No part of the animal entered the human or animal food chain. The cow had resided on the farm for less than a year. The investigation has been completed.
  • On June 24, 2005, BSE was confirmed in a cow slaughtered in November 2004. The cow was sampled for BSE at a pet food facility in Texas. DNA tests confirmed that the approximately 12–year old Brahma–cross cow was born and raised in Texas. The herd was quarantined and cattle that were in a similar birth group and/or ate the same feed as the infected cow were traced and removed.
  • The first case detected in the U.S. was confirmed on December 25, 2003, by The Veterinary Laboratories Agency in Weybridge, England. This case was in an adult Holstein cow slaughtered in the State of Washington. The epidemiological investigation and DNA test results confirmed the infected cow was not indigenous to the U.S., but was born and became infected in Alberta, Canada. Animals with known or potential risk for having been infected with the BSE agent and all progeny from the index cow in the U.S. were depopulated. All carcasses were properly disposed of in accordance with Federal, State, and local regulations.

blue wedge Prevention in the United States (+/-)

Since 1989, the U.S. Government has taken a series of preventive actions to protect against this animal disease. This includes USDA prohibitions on the importation of live ruminants, such as cattle, sheep, goats and most ruminant products from countries that have been or are considered to be at risk for having BSE.

In August 1997, the Food and Drug Administration promulgated regulations to prohibit the recycling of the high-risk material in animal feed. The rule prohibited feeding most rendered material from mammals to cattle or other ruminant animals. In 2008, these feed controls were enhanced to prohibit certain cattle origin proteins, including potentially BSE infectious tissues known as "specified risk materials" (SRM), from all animal feeds, pet foods and fertilizers.

In addition, the FDA and the state regulatory agencies have increased the number of inspections of renderers, animal feed manufacturers, feed mills, and other firms responsible for keeping prohibited mammalian protein out of cattle and other ruminant feed. FDA has dedicated more resources to these animal feed inspections and has upgraded its tracking system and database to ensure effective and timely follow–up.

Since the animal feed rule became effective in August 1997, FDA continues to annually inspect the firms that actually handle prohibited material.

    On December 30, 2003 the USDA announced additional safeguards against BSE:

  • Ban non–ambulatory cattle from the human food chain
  • Ban specified risk materials (skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsal root ganglia) of cattle over 30 months of age and a portion of the small intestine of cattle of all ages from human food
  • Hold cattle tested for BSE at slaughter until confirmed negative for BSE
  • Ban neural tissue in "advanced meat recovery" products labeled "meat"
  • Ban air–injection stunning
  • Ban mechanically separated meat in human food
  • Implement a national animal identification system.

In 2005, a risk assessment done by Harvard University showed the risk of BSE occurring in the United States as extremely low. The report also determined that early protection systems put into place by the USDA and Department of Health and Human Services have been largely responsible for keeping BSE out of the United States and in preventing it from spreading.

FDA Feed Control Information
Harvard Risk Assessment

blue wedge Surveillance in the United States (+/-)

BSE surveillance began in 1990. USDA has an ongoing, comprehensive, interagency surveillance program to detect signs of BSE in the United States. USDA's BSE surveillance program samples approximately 40,000 animals each year and targets cattle populations where the disease is most likely to be found.

The targeted population for ongoing surveillance focuses on cattle exhibiting signs of central nervous disorders or any other signs that may be associated with BSE, including emaciation or injury, and dead cattle, as well as non-ambulatory animals. Samples from the targeted population are taken at farms, veterinary diagnostic laboratories, public health laboratories, slaughter facilities, veterinary clinics, and livestock markets. In addition, approximately 5,000 samples each year are collected from renderers and similar salvage facilities.

USDA will help defray costs incurred for transportation, disposal, storage and testing. For more information on the USDA-APHIS BSE Ongoing Surveillance Plan, visit their website here.


  • Ensuring all cattle, including dead animals, are identified before leaving the premises
  • Keeping accurate animal identification and movement records
  • Keeping accurate feed records
  • Reporting cattle with neurological signs to your veterinarian
  • Disposing of carcasses appropriately, such as with a licensed renderer.

To report high-risk cattle contact USDA-APHIS at this toll-free number: 1-866-536-7593

blue wedge BSE and Human Health (+/-)

Protecting Consumers

    In 2016, the FDA finalized three interim rules from 2004, 2005 and 2008 designed to reduce the risk of people being exposed to material potentially contaminated with BSE. The final rule specifies cattle origin materials that are prohibited from use in FDA-regulated human food, including dietary supplements, and cosmetics. The prohibited materials include:

  • Specified risk materials (SRMs) which include the brain, skull, eyes, trigeminal ganglia, spinal cord, vertebral column, and dorsal root ganglia of cattle 30 months or over, as well as the tonsils and distal ileum of the small intestine from any cattle
  • Small intestine of all cattle unless the distal ileum has been properly removed
  • Material from non-ambulatory disabled cattle
  • Material from cattle not inspected and passed for human consumption by regulatory authority
  • Mechanically separated beef

FDA Announces Final Rule on BSE

Variant Creutzfeldt-Jakob Disease

Scientific evidence shows the same disease agent that causes BSE in cattle also causes the new human disease, variant Creutzfeldt–Jakob disease (vCJD). Variant CJD is a rare, degenerative, fatal brain disorder in humans. The probable transmission of vCJD is consumption of the BSE agent.

The vCJD can be confirmed only through examination of brain tissue obtained by biopsy or at autopsy.


  • Predominantly affects younger people
  • Prominent psychiatric or sensory symptoms at the time of clinical presentation
  • Delayed onset of neurologic abnormalities, including ataxia within weeks or months, dementia and myoclonus late in the illness, a duration of illness of at least 6 months
  • Diffusely abnormal non-diagnostic electroencephalogram.

California Creutzfeldt–Jakob Disease (CJD) Surveillance Project

The California Creutzfeldt–Jakob Disease Surveillance Project is funded by the federal Centers for Disease Control and Prevention (CDC) through the California Emerging Infections Program (EIP) to improve the public health capacity to detect cases of CJD.

blue wedge Compliance with the Ruminant Feed Ban in California (+/-)

California's rendering industry processes over one million tons of waste material to produce about 275,000 tons of animal product yearly. Approximately 50% of the rendered product made in California is exported. The remainder is used in California in feed for swine, poultry and aquaculture, and as fertilizer. Through a partnership agreement with the FDA, personnel with the Feed, Fertilizer, and Livestock Drugs Regulatory Services (FFLDRS) Branch of CDFA are commissioned and credentialed to inspect and complete an official Food and Drug Administration inspection report for feed-manufacturing facilities in California.

In cooperation with the FDA, all facilities that manufacture formula feeds in California have been inspected for compliance with the ruminant feed ban, in addition to all rendering/protein blending firms. Inspections conducted at feed manufacturing facilities and ruminant feeding operations during the past 12 months have found no significant deviations from the FDA Rule on prohibited animal proteins.

Regulatory personnel regularly visit manufacturing facilities that use prohibited materials. Inspections and sampling of ingredients and finished feeds are conducted to ensure ongoing compliance with the ruminant feed ban. Additionally, dairy-producer facilities are inspected for compliance with the feed ban.

All feeds containing animal protein prohibited from ruminant feed are required by federal and state law to display on the label the cautionary statement, "Do Not Feed to Cattle or Other Ruminants". Compliance with the ruminant feed ban is also included as part of a comprehensive voluntary feed quality assurance inspection program for feed-manufacturing facilities conducted under the auspices of the Safe Animal Feed and Education Program of CDFA. Training seminars for the livestock feeding industry and commercial feed manufacturers have been given in cooperation with the FDA. Information on BSE prevention has also been provided to each dairy producer in CDFA newsletters.

CDFA Safe Animal Feed & Education Program (SAFE)