An old standby treatment when sheep become sick is a bottle of whiskey. The whiskey treatment is for the shepherd and not the sheep. Most likely, a treatment tradition started by our Scottish friends.

It is true that sheep tend to have more health problems than cattle. However, it takes a pile of dead sheep to equal the value of a dead cow. Livestock economics and production need to be considered in a relative manner.

Why do sheep have a reputation as being fragile in regard to health status? Consider the productivity of sheep. A ewe produces wool, lambs, and milk to feed the lambs. Often, this is a forage based nutritional program. Thus, a ewe spends much energy and other nutrients in producing saleable products. This leaves less energy to fight off disease and other maladies.

Also, as alluded to earlier, sheep can take much abuse and mismanagement and still live. However, when the threshold is reached, a sheep's system seems to break down quickly.

Prevention of disease and early treatment if it occurs, is the most effective strategy when dealing with flock health. Prevention really is the key, especially when treatment costs and loss of productivity of the flock are considered. The adage "an ounce of prevention is worth a pound of cure" is very applicable to sheep.

Diseases can be classified as nutritional, bacterial and viral in nature. Certainly, this is a simplified categorization and in reality nutrition, bacterial and viral agents work in concert during many disease outbreaks. Further disease classifications include diseases primarily or solely affecting lambs, rams or ewes.

I once read somewhere that a "sheep is another sheeps worst enemy". There is much truth to this statement. Especially, if one has a healthy, closed flock, introduction of disease through contact with outside sheep is the most common method of introducing disease. This contact is generally through the purchase of sheep. If a flock is disease free all reasonable attempts to prevent disease introduction is effort well spent.

A disease prevention program also consists of a planned vaccination program for diseases or conditions prevalent on your farm. Also, one should at least go introduce themselves to their veterinarian, so when an emergency arises they are not dealing with a stranger.

Overcrowding and poor sanitation in intensive production systems often lead to disease. Overcrowding by itself is stressful to sheep. Also, the close proximity allows contagious diseases to be spread more quickly.

A brief discussion of some of the more common diseases to sheep will follow. It is beyond the scope of this article to discuss all associated with each disease.

FOOTROT:

Footrot is an economically important disease due to lowered animal productivity and performance, cost of treatment and especially labor involved in treatment. Footrot outbreaks are dependent on the presence of two bacteria (Fusobacterium necrophorum and Bacterioides nodusus). When environmental conditions include warmth, moisture and mud and both types of bacteria are present, footrot can result. Both types of bacteria are anaerobic. Depending on the strain (more than 20 strains) of B. Nodusus bacteria, footrot can be mildly irritating to sheep or it can be severely debilitating.

Footrot is overwhelmingly introduced into a flock free of the disease by the introduction of infected or carrier sheep. The B. Nodusus organism only lives in soil or on the premises for 14 to 21 days. However, it can live in cracks and crevices of sheep feet for months.

Do not buy footrot, especially if your flock is clean. Once established, footrot is very difficult to eradicate. Treatments include the use of drying agents such as zinc sulfate, copper sulfate or formaldehyde.

ABORTIVE DISEASES:

Certainly, ewes prematurely giving birth to dead lambs will affect the productivity of a sheep enterprise. Also, full term lambs that are small, weak and slow to nurse are a management problem. Several of the abortive diseases have a human health and possibly a dog health concern.

The four most common diseases causing abortions are:

Enzootic abortion (EAE or chlamydia)

Campylobacteriosis (Vibriosis)

Toxoplasmosis

Leptospirosis

Each of these diseases could more than fill an article by themselves. There is information available on each one from numerous sheep and animal health books. Each will be briefly discussed.

Enzootic abortion is caused by a chlamydia type bacteria and results in abortions during the last month of pregnancy, still births or weak lambs. Chlamydia can also infect cattle, goats and occasionally people. Chlamydia seems to primarily affect younger ewes that have not developed an immunity to the bacteria. Chlamydia exerts damage to the feti primarily by causing damage to the placenta.

Because the placenta is damaged, the best treatment for chlamydia is prevention. Prevention is best accomplished by vaccination prior to conception.

Vibriosis or campylobacteriosis is another abortive disease caused by a bacterial infection. There are eight known strains of bacteria. Vibrio also affects ewes in late gestation. Vibriosis is fairly common and can be prevented by vaccination before breeding, again during the last trimester and by feeding high levels of antibiotics.

Leptospirosis is another bacterial abortive disease that affects sheep, cattle, swine, dogs and many species of wildlife. With lepto, abortions usually occur about eight weeks before lambing, but can occur anytime during pregnancy. Lepto is easily prevented by a once yearly vaccination.

Toxoplasmosis is a condition discovered relatively recently. Toxoplasmosis is actually a parasite commonly infecting cats. These oocytes infect sheep and can cause embryonic death and resorption, mummification of feti, abortion or weak lambs, depending on stage of pregnancy infected. Toxo damages the uterus and fetus of sheep.

Toxoplasmosis is prevented by controlling the cat population on a farm or by feeding the ionophore monensin. There is no vaccine and antibiotics or ineffective against the oocytes. Toxoplasmosis can infect people, thus, pregnant women should be careful in the lambing barn and when around young cats.

PNEUMONIA:

There are many types of pneumonia that affect sheep. Basically, pneumonia is caused by a mix of stress, and microorganisms working synergically to cause lung tissue damage. Stress can include poor sanitation, overcrowding, shipping, build-up of irritating gases, dust or numerous other conditions. Microorganisms crucial to pneumonia development include viral and bacterial agents. Some of the viruses include; parainfluenza (PI3), respiratory syncytial virus (RSV), adenoviruses and reoviruses. Bacterial agents include; pasteurella (most common), mycoplasma and chlamydia.

To prevent pneumonia, the key is to eliminate one of the causes. Usually, the most practical is to manage the stress aspect, although there are vaccination protocols that can be used, depending on type of pneumonia. Treatment generally consists of antibiotic, tetracycline and sulfa administration.

CLOSTRIDIAL DISEASES:

The clostridial diseases most likely to affect sheep producers include clostridial perfringens type C&D and tetanus. Clostridial perfringens bacteria cause enterotoxemia or overeating disease. Type C is also known as hemorrhagic enterotoxemia and infects lambs up to about three to four days. Type D clostridial bacteria normally inhabit the gut and during times of rapid, large feed intake proliferate. When large numbers occur, they release a toxin that kills the lamb or sheep. The good thing about overeating and tetanus is they are easily prevented by a vaccination program.

MASTITIS:

Mastitis in ewes is one of the leading causes of culling in the ewe flock. Mastitis can be of the acute, gangrenous type or of a subclinical type of mastitis. Mastitis can affect one or both halves of the udder either with full damage or partial damage.

Mastitis is caused by bacterial infections. When one considers the mammary system, it is an ideal environment for bacterial growth. Temperature is constant and there is a constant supply of food. Since bacterial populations can explode in numbers in a short time period, it is important to treat mastitis in a timely fashion.

Proper management of ewes at weaning is crucial to preventing mastitis, especially for ewes undergoing early (60 to 100 days) weaning.

DIGESTIVE DISEASES:

Acidosis and bloat are diseases of economic significance to the sheep enterprise. Acidosis is generally caused by a rapid increase in highly digested energy sources (grains). The rumen acid levels can increase to a dangerous level and metabolic disturbances and death can result. Adoption to grain diets should occur over a 7 to 14-day period to prevent acidosis.

Bloat can be a problem in sheep grazing or eating high levels of legumes, particularly alfalfa and many of the clovers. Bloat is best prevented by feeding a bloat block (poloxene) and by putting sheep onto legumes after they are full. Dew on fresh growing forages has been shown to be a contributing factor in bloat. Propensity to bloat has also been linked genetically to certain lines or breeds of sheep.

SCOURS:

Scours or loose feces can be caused by a variety of factors with a wide range in seriousness. Scours in young lambs (up to seven days of age) is a very serious situation if caused by E. Coli bacteria. Young lambs can dehydrate quickly and death can result. Scours in older animals because of intake of fresh, growing forage is not very serious but can be unsightly and reduce wool value.

Scours are often an indication of a problem. For instance, wormy sheep often will have scours. Lambs with coccidia will often scour. Scours are usually a symptom of a problem. 

SUMMARY

By no means can all sheep diseases be covered in a single article. There is much information available in popular sheep press, books, manuals, at sheep field days and from your veterinarian.

The key to disease control is prevention. A sick sheep is not always a dead sheep, especially if conditions are caught quickly and prevented. Prevention occurs most effectively by sanitation, controlling exposure to outside animals and by managing health concerns by a vaccination program.

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