In
equids, it is most common in the first twelve months of life. Neonatal foals born to dams that are selenium-deficient often develop the condition. There are two forms: peracute and subacute. The peracute form is characterized by recumbency,
tachypnea,
dyspnea,
myalgia, cardiac arrhythmias, and rapid death. The subacute form causes weakness,
fasciculations, cramping, and stiffness of muscles, which can lead to recumbency, as well as a stilted gait,
dysphagia,
ptyalism, and a weak suckle. Other
sequelae include aspiration pneumonia, failure of passive transfer, and stunting of growth. Clinical laboratory changes include evidence of
rhabdomyolysis (elevated CK and AST,
myoglobinuria) and low blood selenium levels. On necropsy, muscles are pale with areas of
necrosis and
edema evidenced as white streaks. EDM is a more severe form of NAD. The diseases are characterized by the damage and degeneration of the
central nervous system. This disease process is heritable in certain breed bloodlines, such as
Quarter Horse,
Appaloosa,
Morgan,
Lusitano, and
Arabian. It is hypothesized that horses develop this disease continuum because they have a defect in the uptake or utilization of Vitamin E and therefore have a higher baseline requirement. == Sheep (stiff lamb disease) ==