Re: Can mad cow disease be transmitted to equines?

Dear Nanci,

Good question! As with all things Mad-Cow related, it's either "we think so," or "we don't think so." In this partiucular case it is "we don't think so."

Horses (equines in general) are not known to carry prion diseases like Bovine Spongiform Encephalopathy. (BSE) In fact, because of that, horseflesh is becoming a hot commodity in countries gripped with fear of Mad Cow disease. Horseburgers anyone?

However, just because horses are not *known* to carry mad cow disease doesn't mean they can't get it. Some scientists would argue that they just haven't gotten it yet.

Many believe that cows developed BSE from being fed MBM, that is Meat- and-Bone-Meal. MBM is a food source used as a protien supplement made from the ground-up remains of other cows, pets, and circus animals. Horses are not typically given this kind of feed, and so wouldn't have the exposure that cows have had to it.

Scientists are investigating the possibility of horizontal transmission. That is the transmission of the disease from one animal to another. In humans you could think of the flu as being horizontally transmitted, whereas salmonella is not. If one living cow can infect another living cow, then it is theoretically possible that a living cow could infect a living horse. At this point that seems very unlikely.

Current research indicates that under the right conditions any mammal can be given a prion disease. Some animals are easier to infect than others, but in the experiments where ground up infected neural tissue was injected into a live subject's brain tissue, prion diseases have shown up in many different types of animals like hamsters, mice, and pigs. So, in summary, horses probably could get Mad Cow disease under the right circumstances. (like in the lab) In nature, however, it seems very unlikely that they would develop Mad Cow disease.

I hope that answers your questions. Thanks for asking and if you have any more questions don't hesitate to ask!

Mike Gasink - Mad *Cow* Scientist. Here's some links http://www.theatlantic.com/cgi-bin/o/issues/98sep/madcow.htm
www.mad-cow.org
www.cjd.org

Richard Rhodes' book, Deadly Feasts is a MUST READ for anyone interested in the history of Mad Cow diease and prion diseases in general.