mad cow disease

Bovine spongiform encephalopathy, also known as mad cow disease, is a cumulative neurologic disease in cows. That means that it attacks the cow’s central nervous system and progressively gets worse over time. BSE was first discovered in 2003 in a cow imported from Canada. 

Scientists state that it is caused by a protein called a prion. They do not know why but think these normal proteins mutate into harmful ones. Scientists infer that the reason this disease has caused so much disruption is that the cow's body is unable to recognize the prion turning harmful, therefore its immune system cannot fight against it. 

Signs of mad cow disease include: incoordination, aggression, and skittish behavior. This is why it is called “mad cow disease”. It can take up to six years for the cow to even begin showing symptoms after it is infected. Once it starts showing signs, it can take as little as two weeks for the cow to die. There has been no prevention method or treatment found for BSE. There is also no way to test for BSE in a live cow; only after it dies can the disease be found in its brain tissue. 

Cow parts that humans do not consume are ground up and used in feed for other cows. The most common way a cow contracts mad cow disease is through feed contaminated from a past cow that had BSE. It is rare, but humans can get a variant of mad cow disease, called Creutzfeldt-Jakob disease (vCJD), from eating affected beef. However, most people who died from this were overseas when they contracted it. 

The FDA is taking measures to keep us and animals isolated from BSE. Since 1997, they have not allowed cow parts to be in feed that is fed to other animals. They also work with USDA to keep high-risk foreign cows/cow products out of the U.S.

There are other diseases similar to this in other livestock and animals. For example, scrapie can be found in sheep and goats. And a chronic waste disease in deer. Mad cow disease is not well understood, but many measures are being taken to proactively learn more about it and how we can prevent it.

"All About BSE (Mad Cow Disease)". U.S. Food And Drug Administration, 2020, https://www.fda.gov/animal-veterinary/animal-health-literacy/all-about-bse-mad-cow-disease. Accessed 3 May 2023.

Bovine spongiform encephalopathy (mad cow disease) (no date) Agr. Available at: https://agr.illinois.gov/animals/animalhealth/animaldiseases/bse.html. Accessed 3 May 2023.