Mad Cow Disease: Information for Educators

---

There has been much discussion about Bovine Spongiform Encephalopathy (BSE), commonly known as Mad Cow Disease, in recent months. This has been especially true since the discovery of a single U.S. case of the disease in December 2003. So it is not surprising that some educators, students, and parents have raised questions about the safety of dissecting our preserved bovine specimens, such as eyes, hearts, spinal cord sections, and testicles. By presenting a concise summary of what is currently known about BSE and what we do to ensure our specimens are as safe as reasonably possible, we hope to help you make an informed decision about whether or not to dissect these specimens in your laboratory.

The infectious agents that cause BSE are called prions. Prions are malformed strands of proteins that, in their normal version, are produced by and are naturally present in mammalian brains. Through a process that is not yet fully understood, in the brains of a very small number of mammals the mechanism of protein production malfunctions and produces infectious prions.

BSE is only manifested in cattle 36 months old or older. It was transmitted to cattle in the United Kingdom and other European nations some years back because brains and spinal tissues of slaughtered animals were processed and used as protein sources in cattle feed.

As we mentioned earlier, only a single case of BSE is known to have occurred in the U.S. The United States Department of Agriculture (USDA) moved immediately to destroy the infected cow and any cattle with a “relationship” to it, e.g., were in the same herd, had close contact, or the same parentage. The chance of infection being present in any tissues from a U.S. cow is very, very low.

Our preserved bovine specimens are by-products of the meat industry, purchased exclusively from reputable U.S. suppliers. We only use tissues from cows that are under 24 months of age at the time of slaughter. As mentioned earlier, BSE has not been found in cattle less than 36 months of age.

All these factors taken together mean that the chance of our acquiring specimens from an infected cow is exceedingly small. Also bear in mind that while it is true that prions have been found in the brain, spinal cord, and eyes of infected cattle, they have not been found in their hearts or testicles.

To further minimize the possibility that infection could be present, we add phenol to the fixatives and preservatives applied to cow eyes and spinal tissues. Phenol has been shown to be effective in deactivating prions, but it is not 100% effective. The only method considered 100% effective is long-term exposure to heat and pressure. This would certainly destroy preserved specimens. Exposure to phenol, though, should significantly decrease the number of prions in the highly unlikely event that any are present at all.

Note that all human cases of BSE, known as Variant Creutzfeldt-Jakob Disease (vCJD), have been blamed on consuming infected beef products in countries other than the U.S. Our preserved bovine materials are absolutely not intended or suited for human consumption, and it is not reasonably expected that any person would consume them.

Safe handling of preserved bovine specimens provides additional safeguards against the very remote possibility that they could be infected. As is always the case with dissection, we recommend using the following good laboratory practices during the procedure:

These practices must be followed whenever dealing with any biological or chemical materials in the laboratory to ensure that the person handling the materials never directly contacts them.

While we take all reasonable precautions to minimize the risk of BSE in our preserved bovine specimens, we cannot certify that all specimens are free of prions. There still exists a miniscule possibility that prions could be present. Absolute certification would require extensive testing of every specimen at great expense. It would be so impractical as to be nearly impossible, and the benefits would be minimal because the risk of infection is already so low.

We have taken many steps through the years to bring you safe preserved specimens of the highest quality. The same is the case with preserved bovine specimens. We have enhanced our processes to ensure that the specimens we offer are as safe as it is reasonably possible to make them. Although it appears that the risk is minimal, each educator must evaluate from available information whether or not it is safe to dissect preserved bovine specimens. Hopefully, we have presented you with the information you need to make that decision. If you have any further questions or concerns, please feel free to contact our Product Information Group at 800.227.1150.