• Disease that results in wool loss or lower quality wool; and

• Labor costs associated with treatment.

Maintaining the health of the national flock has even broader implications than for any given individual flock. An introduction of a foreign animal disease or an endemic disease that mutates may result in large-scale repercussions such as a food safety event that could result in human illness and decreased consumer confidence. In the past decade, > 70 percent of the emerging diseases have been zoonotic (Woolhouse and Gowtage-Sequeria, 2005). The U.S. sheep industry has been fortunate to avoid a significant crisis resulting from a highly contagious or zoonotic disease outbreak. To prevent complacency, the industry as a whole will need to systematically review worldwide conditions and disease reports as well as suspicions of diseases mutating to a more virulent strain. One of the greatest vulnerabilities is the risk of introducing a foreign animal disease. When introduced into a native population, foreign animal diseases may spread rapidly because the animals have no immunity to the disease. In many cases, the outbreaks result in a high death losses and/or severe production losses. To illustrate that the cost of prevention is usually much less expensive than control or elimination, the World Organization for Animal Health (OIE) commissioned a study to compare the cost of preparedness and prevention versus the cost of control for avian influenza. Even without considering the indirect financial impacts, the benefits of prevention far outweighed the potential outbreak costs and losses (Agra CEAS Consulting, 2007).

The intent of this chapter is to examine broad issues regarding health and how they may impact the economic viability of the sheep industry as a whole, as well as individual sheep operations. The chapter is not intended to serve as a comprehensive review of sheep diseases. Certain diseases are highlighted to illustrate different points. A detailed review of scrapie is included because it is the only sheep disease that has had a congressionally funded control program in place for over 50 years.

Sound flock health management practices are the key to disease prevention and control. While it is important to have vaccination and treatment programs for specific diseases, a holistic approach founded on prevention can be the most effective tool for maintaining a healthy flock. This in turn increases productivity. The basic management tools include:

• Biosecurity, including maintaining a closed flock or restricting the number and source of replacements;

• Recordkeeping, including animal identification;