Management practices can be the primary determinant of cases or outbreaks of infectious or metabolic disease in all flocks of sheep.

Pregnancy toxemia (see Hepatic Lipidosis: Pregnancy Toxemia in Ewes) may be seen in late-pregnant ewes subjected to a falling plane of nutrition, especially ewes with twins or triplets. It is also associated with starvation, ewes that are too fat in early pregnancy, ewes that are fat in late pregnancy and voluntarily reduce feed intake, and ewes subjected to stress in late pregnancy, such as transport or other environmental changes.

Hypocalcemia (see Disorders of Calcium Metabolism: Parturient Paresis in Sheep and Goats) is seen in pregnant ewes or ewes in early lactation subjected to a period of temporary starvation, especially ewes with twins or triplets; as a result of decreased food intake in late pregnancy; and in weaner sheep on a grain-based ration during drought conditions.

Hypomagnesemia (see Disorders of Magnesium Metabolism) may be seen during a period of temporary starvation in late pregnancy or early lactation, after movement of lactating ewes to lush growing pasture (especially green cereal crops), or among lactating ewes on rapidly growing pastures (eg, spring growth).

Dermatophilosis (see Dermatophilosis) is associated with poor shearing practices leading to shearing cuts, dipping immediately after shearing with contaminated dip, and sheep in long wool at times of high rainfall. Some sheep are also genetically predisposed.

Caseous lymphadenitis (see Lymphadenitis and Lymphangitis) may be associated with not shearing according to ascending age groups, not separating infected or discharging sheep before shearing, close confinement (nose to fleece) of sheep after shearing and dipping, and contaminated dip.

Pulpy kidney disease (Clostridium perfringens type D infection, see Clostridial Diseases: Type D Enterotoxemia) is seen in sheep on a rising plane of nutrition, such as those moved to better pasture, following a “flush” in pasture growth, or in sheep fed grain. C perfringens type C infection is seen in artificially reared “bummer” lambs.

Malignant edema (see Clostridial Diseases: Malignant Edema) and blackleg (see Clostridial Diseases: Blackleg) may follow wounds (eg, improper shearing, vaccination).

Tetanus (see Clostridial Diseases: Tetanus) may also be seen after a wound associated with procedures, such as castration, docking, improper shearing, or vaccination, performed in contaminated permanent yards.

Black disease (see Clostridial Diseases: Infectious Necrotic Hepatitis) is seen among grazing sheep on pastures that support the intermediate host of Fasciola hepatica.

Erysipelas arthritis (see Erysipelothrix rhusiopathiae Infection) is associated with contaminated dip, and poor hygiene at docking, castration, and lambing.

Ovine posthitis is seen in merino wethers on high protein pasture.

Squamous cell carcinoma is seen on the vulva of short tail docked or mulesed sheep.

Actinobacillosis (see Actinobacillosis) is seen in sheep grazing on abrasive, thorny pasture.

For disease risks associated with pasture or with specific plants (eg, the risk of bloat, polioencephalomalacia, hemolytic anemia, esophageal obstruction, and enterotoxemia in sheep, and goiter in the lambs of pregnant ewes grazing Brassica spp), see Plants Poisonous to Animals. For the risk of nutritional deficiency or toxic disease associated with formulated feeds, see Nutrition: Sheep.

Last full review/revision July 2011 by Clive C. Gay, DVM, MVSc, DVSc (Hons), FACVSc, DACIM (Hons)