Enzootic Ataxia

Although most often reported as a problem in Australian sheep, enzootic ataxia has been reported in goats in the United States. First, two definitions: enzootic means an animal disease or condition common in a certain area; and ataxia means incoordination due to a disorder of the nervous system.

Enzootic ataxia is caused by copper deficiency and can manifest itself in two ways in kids. The congenital form (present at birth) is called swayback. These kids may be unable to rise or may walk with severe incoordination. They may be depressed and have muscle tremors; most die soon after birth. These signs are due to the loss or abnormal formation of the “insulation” portion of the nervous system (myelin) and damage to some motor nerve cells.

True enzootic ataxia is the second form of this condition; it has a delayed onset of signs. Affected kids actually appear normal at birth but start showing problems between one week and six months of age. These animals are ataxic and also usually show hindquarter weakness or paralysis.

Both swayback and enzootic ataxia are caused by copper deficiency. This deficiency can be primary (diet low in copper) or secondary (dietary factors that affect how much dietary copper is absorbed). Copper is poorly absorbed from fresh forage, so grazing and browsing animals are most at risk of deficiency. Copper is more available from grains and hay, but these feedstuffs can be low in actual copper content. High levels of molybdenum and/or sulfur in the diet can interfere with copper availability and absorption, so deficiencies can occur despite the presence of adequate copper in the diet.

Diagnosis can be definitively determined by physical examination, laboratory tests, necropsy lesions, and review of local copper status. Affected animals can be supported with palliative treatment (physical therapy, thick bedding, nearby food and water, etc.) but their conditions do not improve and most are euthanized.

Prevent both forms of enzootic abortion by ensuring adequate copper in the diets of pregnant does, especially in the last half of gestation. This may require supplemental copper in some areas. Ask your veterinarian or animal-nutrition consultant for advice. Do not use mineral mixes formulated for sheep because these have restricted copper levels that are often inadequate for goats.