Agriculture Reference
In-Depth Information
In the male, lesions also appear on the penis and prepuce while in the female lesions will ap-
pear on the vulva and teats. It is a zoonotic disease that can be transmitted to humans. Orf is
spread by direct contact, including breeding. Animals might be reluctant to mate due to the
pain of the lesions. The disease typically runs its course in three to four weeks. Secondary
bacterial infections can happen that lead to more debilitating conditions such as damage to the
reproductive tract or deep tissue infections.
Scrapie:
Scrapie is a degenerative disease of the sheep's nervous system. The disease has a
long incubation period before signs are noticed. It is similar to other diseases that affect the
nervous system such as bovine spongiform encephalopathy (BSE) of cattle, chronic wasting
disease of deer and elk, and Creutzfeldt-Jakob disease of humans. Scrapie is caused by a tiny
piece of protein (prion) that is very resistant to heat or disinfectants. It is spread from infected
sheep to other infected sheep, most commonly from an infected mother to her lambs. Lambs
during their first few months of life are most susceptible to contracting scrapie. It is believed
that some sheep are more genetically susceptible to scrapie. The disease is found worldwide
and was first diagnosed in the United States in 1947 in Michigan.
A prion enters the body through the mouth. For the first two years, it remains in the body in
low levels in the lymph nodes. Then it spreads to the nervous system and multiplies rapidly,
causing damage to the nerve cells. Sheep will show signs such as tremors, lack of coordina-
tion, behavioral changes, and a manner of walking that looks like a bunny hop. Some sheep
may be intensely itchy, rubbing against objects until their wool is worn off (hence the name
scrapie). The affected sheep will die one to six months after signs occur. Sheep do not develop
immunity to scrapie, so there is no vaccine or cure. There is no simple diagnostic test that can
be performed on live animals and no treatment. If the disease is found in a flock, all infected
ewes, rams, and their offspring are killed by the authorities, the premises will need to be rigor-
ously cleaned, and the federal government will monitor the flock to tract the progression of
the disease. There is currently a nationwide scrapie tagging program but it is administered at
the state level with different requirements from state to state. Talk to your local extension ser-
vice agent to find out what the requirements are in your state.
Breeding Sheep
A female lamb will reach puberty when she is between 5 and 12 months old. Weight, breed,
genetics, and her nutritional status influence when she will come into estrus and is ready to
stand for mating. Single-born lambs, larger lambs, heavy-fed lambs, and lambs born early in
