SCRAPIE

Scrapie is a fatal degenerative disease of the central nervous system of sheep and goats. Although Scrapie doesn't cross species, it is a member of the family of diseases known as Transmissible Spongiform Encephalopathies (TSE's) that includes "Mad Cow Disease" in cattle and Chronic Wasting Disease in deer and elk. Over a period of years, infected and/or susceptible herds become economically unviable as younger and younger animals succumb to the disease. Animals sold from infected herds spread this incurable illness. The existence of Scrapie in the United States prevents the export of breeding stock, semen, and embryos to other countries from herds with known or suspected exposure to scrapie. Captive wild animals have contracted TSE's, but only as a result of being fed TSE-contaminated feed.

First identified in sheep in Great Britain and other Western European countries more than 250 years ago, Scrapie exists throughout the world. Only two countries are certified Scrapie-free: New Zealand and Australia. Scrapie first appeared in the United States in 1947 in a flock of sheep in Michigan. From 1947 through July 2001, over 1600 head of sheep have been diagnosed with Scrapie. In that same timeframe, only seven cases in goats have been reported. Nevertheless, goats as well as sheep have been targeted in governmental efforts to control the spread of Scrapie.

A slow-developing disease, Scrapie detection is difficult on animals under 18 months of age. Currently the only diagnostic tool for goats is to necropsy the brain tissue of a dead goat. Most of the research on Scrapie has been done on sheep, because sheep is the species in which Scrapie has been overwhelmingly diagnosed. Scrapie incidence in goats has been very low, but this may be the result of little attention being paid to goats overall.

Symptoms vary widely and develop slowly. Because the nerve cells are damaged, infected animals display head and neck tremor, skin itching, inability to control leg movement (swaying in the back end, hopping like a rabbit, high stepping of the front legs), lip smacking, good appetite accompanied by weight loss, rubbing against fences and other fixed objects, and biting of feet and legs. The name Scrapie comes from the scraping action the animal displays as it scrapes its hair/hide off. The symptoms are so generalized that they can be easily misdiagnosed. Veterinary disagnosis on-farm is done by visual observation only, and all suspect animals must be reported to Federal authorities. This can lead to problems for the producer whose herd may really be free of Scrapie, but the veterinarian is obligated to err on the side of caution. The United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) is currently working on a live-animal diagnostic test using procedures that detect the presence of an abnormal prion protein in sheep; however, genetic testing is not available for goats.

There are three main theories about how Scrapie is transmitted; it may be caused by a virus, a prion, or a virino. The majority of scientists tend to believe that an abnormal form of a prion protein is the agent in question. There appears to be a very distinct genetic component to Scrapie. Animals with specific gene patterns may display either a resistance or a susceptibility to contracting Scrapie. It appears that certain genetic patterns (in sheep) allow changes in the prion cellular protein structure that somehow prevent contraction of the disease. Studies are underway to determine how this works. Gene manipulation may be able to create animals that are Scrapie resistant. Unfortunately, goats are not part of these studies.

The details of how Scrapie is thought to work are technical and complex. The goat producer should be more interested in prevention rather than in learning the intricate details of the science behind Scrapie transmission. It is important to know that whatever the Scrapie agent turns out to be, scientists know that it is (a) very resistant to heat, and (b) does not cause any inflammatory reactions or immune system responses in the infected goat or sheep, thereby making current live-animal diagnostic testing techniques useless.

Scientists believe that Scrapie is spread from dam to offspring and other animals through contact with placental fluids. The role of artificial insemination and embryo transfer in the transmission of Scrapie is also under investigation. First symptoms often don't appear for two to five years after infection, meaning that many other animals could have also been infected long before detection occurred in a single animal. Death occurs within one to six months after symptoms appear. The disease is always fatal to the animal.

There is no scientific evidence that Scrapie is hazardous to human health in any manner, even through the consumption of the meat or milk of infected animals.

Control over the spread of Scrapie has been focused on (a) the establishment of a nation-wide Scrapie tagging program (administered at the State level, with differing regulations from State to State, but subject to minimum requirements set at the Federal level) to identify and trace the movement of goats and sheep; (b) genetic testing through the National Genetics Based Flock Cleanup Program (limited to sheep only); (c) eradication (de-population) of animals identified as infected, and (d) research aimed at finding genetic-based resistance to Scrapie. Goat producers will be interested and dismayed to learn that the genetic testing part of the control program involves compensating producers for infected animals but is restricted to sheep breeders only.

The information contained in this article came largely from the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) (1-800-601-9327). APHIS has a section of its website devoted to discussing Scrapie and its eradication efforts.

The author, Suzanne Gasparotto, hereby grants to local goat publications and club newsletters, permission to reprint articles published on the Onion Creek Ranch website under these conditions: THE ARTICLE MUST BE REPRODUCED IN ITS ENTIRETY AND THE AUTHOR'S NAME, ADDRESS, AND CONTACT INFORMATION MUST BE INCLUDED AT THE BEGINNING OF THE REPRINT. We would appreciate notification from any clubs or publications when the articles are used. (A copy of the newsletter or publication would also be a welcome addition to our growing library of goat related information!)

All information and photos copyright © Onion Creek Ranch and may not be used without express written permission of Onion Creek Ranch. TENNESSEE MEAT GOAT ™ and TEXMASTER™ are Trademarks of Onion Creek Ranch . All artwork and graphics © DTP, Ink and Onion Creek Ranch.