Sheep and goat producers should be aware of regulations regarding the disease
Scrapie, a fatal and degenerative disease, is important to keep in mind when considering raising sheep or goats.
While many producers and consumers know about BSE, or mad-cow disease, awareness of the scrapie disease limited outside the sheep show world. Scrapie is a spongiform encephalopathy that affects the central nervous system of sheep and goats, similar to how mad-cow disease effects cattle.
Jason Apple, professor of animal science at the University of Arkansas, said that though the disease has been present in the U.S. since the mid-1940s, producers became more aware of it in the mid-1980s when there was a major outbreak.
“Early on, we knew that it was a problem, but we didn’t know what caused it. There were a lot of misconceptions about what it was; we knew it was some sort of central nervous issue, but we didn’t know how it was transferred,” Apple said.
Transmission of the disease is not completely understood, though there are a few different plausible ideas. Dr. Jennifer Keaton, mixed-animal parasite veterinarian in Anderson, Mo., said the cause isn’t specifically known by veterinarians to this day.
“There are three main theories. One is that it is a virus, another one is that it’s a self-replicating protein (or a prion), and the other one is (that it is) a small nucleic acid modifier, like a protein, that is encoded into the host DNA,” Keaton said. “Basically, something changes the host DNA and causes a mutation.”
Apple has a solid theory concerning how the disease is transmitted.
“We are pretty sure that the transmission is through the infected placenta and fluids, from female to offspring. We are 99 percent confident that it isn’t male transmitted,” Apple said.
There are many such theories; however, Keaton said that one thing is certain – animals can carry the disease long before they begin exhibiting symptoms.
“There is a long incubation period, then the infected animals start showing signs. (Scientists) haven’t yet pinpointed what specifically causes it,” Keaton said.
Signs of the disease are first noticeable in 2- to 5-year-old animals and can include intense rubbing of body against barn or fences, incoordination, tremors, star-gazing (when the animal looks up to the sky consistently) and weight loss with no decrease in appetite.
“Early on, it’s a slow, progressive, degenerative type thing – star-gazing happens early. Initially though, it may be subtle changes in their behavior like being apprehensive then aggressive,” Keaton said. “Several months later they become (a loss of coordination of muscles), or clumsy. Later in the progression, they will get floppy ears too, though no one knows why.”
Goats may also show difficulty milking, premature kidding and eating or licking things that shouldn’t normally be consumed.
Apple cautioned there are a few things to consider when selling animals across state lines in order to make sure that infected ewes are not spreading the disease from farm to farm.
“We now have a pretty much mandatory scrapie eradication program. All producers selling female breeding sheep must have a farm premise ID. You can get an official USDA ear tag by calling APHIS. You must have health papers,” Apple said.
While those in the show ring or club lamb growers are familiar with programs to eradicate scrapie, those new to the sheep world may be unfamiliar with matters concerning this fatal disease.
“Club lambs in summer shows are going across state lines to show, and you have to have health papers,” Apple said. “There are not many shows where you will be let into the show ring without a scrapie tag.”
Keaton said there is no sure way to prevent this disease from occurring.
“There is a scrapie flock certification required, but it just proves there’s surveillance over your herd. Be aware of the early signs and isolate or have the animals evaluated before it potentially spreads,” Keaton said.
Apple offered a couple of suggestions in order to help curb transmission. The first is to take care of any female sheep properly after the lambing season.
“I think we can never stress enough cleaning up after the ewes. If we know it’s going to be in the placenta, just clean up after them as soon as possible. Management wise, we can do this (to prevent it),” Apple said.
Apple’s second recommendation is to contact local health professionals, especially a veterinarian familiar with sheep and goats, if there’s a possibility of scrapie on the premises.
“If you think you’ve got it, contact your vet,” Apple said.
There is no cure for scrapie, and once an animal has been infected, it remains so for the rest of its life. Looking for early signs seems to be the best way to help keep an eye on transmitting the disease, Keaton said.
“The bad thing is that the incubation is so long, it’s hard to prevent and detect. By the time you detect it, you may have others already incubating it. Be aggressive with the animals that may be symptomatic to get a diagnosis,” Keaton said.