Metabolic Diseases, Mastitis, Abscesses

By Steven M. Parish and D. Scott Adams.

Metabolic diseases among sheep and goats are wide and varied. Most of the reported conditions occur in association with pregnancy, lactation and/or periods of stress. These disease processes are not contagious but can and do affect groups of animals.

Pregnancy toxemia or twin lamb disease is a condition of thin or overly fat ewes in the last third of pregnancy. Due to rapid growth at this time of the unborn lambs and often a declining plane of nutrition, the ewe may develop hypoglycemia or low blood sugar. Ewes carrying single lambs and ewes lambing for the first time rarely develop this disease.

Because of low blood sugar the ewe ceases eating, becomes uncoordinated and weak. Soon the ewe becomes unable to stand and neurologic signs such as blindness, muscular tremors, convulsions and coma appear, followed by death. Possible treatments include intravenous glucose, oral glucose precursors, vitamins, and possible induced abortion to relieve the ewe of the burden of pregnancy.

Prevention includes maintaining the ewes in moderate condition in early pregnancy, and then increasing the level of nutrition in later pregnancy as demands of the unborn lambs increase. This condition has been reported in goats but is not common.

Lambing Sickness

Low blood calcium (lambing sickness, transport tetany) is associated with several conditions of sheep and goats. The cause is lack of available calcium for metabolism, or a sudden increased demand for calcium by the body which cannot be met.

The disease generally affects fat ewes and goats during the last 6 weeks of pregnancy and during the first week of lactation. It also can occur in rams and bucks and feedlot lambs following fasting and transporting.

Affected sheep and goats in early stages show stiff and incoordinated movements especially in the hind legs followed later by muscle tremors, muscle weakness and breathing problems. In late stages the animals are down, unresponsive and unable to rise. Soon they pass into a coma and die unless treated.

Treatment includes administering calcium products. Prevention includes maintaining adequate levels of calcium in the diet and preventing periods of stress without adequate feed and water.

Low blood magnesium (grass tetany) occurs when milking ewes and does are grazing early spring pasture. Most cases occur in females in the first 4 weeks after giving birth, although other classes of animals occasionally develop the disease. The animals become excited, uncoordinated, become recumbent, convulse, pass into a coma, and die.

Treatment includes administering magnesium-containing products. Prevention includes magnesium supplement in the diet of susceptible animals.

Mastitis

While a myriad of additional diseases may affect sheep and goats, only two additional ones will be discussed in this chapter mastitis and abscesses.

Mastitis, inflammation of the mammary gland, can be caused by a variety of things, but most often results from bacterial infection in both sheep and goats.

In acute clinical (obvious) mastitis of dairy goats, milk production is reduced and the milk often is watery and contains flecks, pus, blood and chunks. The gland often is reddened and harder and warmer than normal. For every case of clinical mastitis, many cases of subclinical mastitis are present and may only reduce milk production.

Sheep with acute clinical mastitis acquire a hard, hot udder and often become very ill with a high fever. In severe cases the udder may become cold and bluish (gangrenous), and death often results.

Most forms of mastitis are spread by contact with the organisms that may be present on milkers' hands, milking equipment, and bedding. Nursing lambs and kids also may transmit the causative organisms. Avoid anything including faulty milking equipment that may damage the udder.

Antibiotics often are helpful. Professional veterinary advice should be sought.

Prevention: In goat dairies, keep milking equipment clean and in good working condition. Good milking practices also will help. Dry treatment with antibiotics, and teat dipping may be advisable. Close observation and reduction of grain and water at weaning of lambs will reduce mastitis in ewes.

Abscesses

These are pus-filled cavities usually seen as external lumps under the skin, particularly around the head and neck. They also may be found in virtually any internal location.

Causes: Many different bacteria and foreign bodies but Corynebacterium pseudo-tuberculosis (ovis), the cause of caseous lymphadenitis, is the most common.

Abscesses under the skin appear as lumps from less than one to several inches in diameter. The signs caused by internal abscesses are highly variable.

Corynebacterium pseudo-tuberculosis is spread by infected animals and remains in the environment for months. It enters the body through cuts and scrapes. It may infect human beings.

For treatment, consult your veterinarian. Abscesses may be opened, drained and flushed with disinfectants like hydrogen peroxide and organic iodine preparations.

Separate infected animals from the others when abscesses are open, as a preventive measure. New additions to the flock should be carefully screened for abscesses. Avoid anything that causes cuts and scrapes to the skin. Disinfect contaminated areas.

Steven M. Parish is Associate Professor, Department of Clinical Veterinary Medicine, Washington State University, Pullman. D. Scott Adams is with USDA's Agricultural Research Service at the Animal Disease Research Unit, Department of Veterinary Microbiology and Pathology, Washington State University.