Swayback

Adverse effects of copper deficiency can be documented in terrestrial plants and invertebrates, poultry, small laboratory animals, livestock — especially ruminants — and humans. Data are scarce or missing on copper deficiency effects in aquatic plants and animals and in avian and mammalian wildlife. Copper deficiency in sheep, the most sensitive ruminant mammal, is associated with depressed growth, bone disorders, depigmentation of hair or wool, abnormal wool growth, fetal death and resorption, depressed estrous, heart failure, cardiovascular defects, gastrointestinal disturbances, swayback, pathologic lesions, and degeneration of the motor tracts of the spinal cord (NAS 1977). 

Lewis, G., S. Terlecki, and R. Allcroft. 1967. The occurrence of swayback in the lambs of ewes fed a semi-purified diet of low copper content. Veterin. Rec. 81 415-416. 

Alloway, B.J. 1973. Copper and molybdenum in swayback pastures. Jour. Agric. Sci. (Cambridge) 80 521-524. 

Failure of the neuron to myelinate because of copper deficiency leads to abnormalities of the nervous system. This was first described in lambs and was referred to as "swaybacks. It is not known whether this is attributable to a diminished level of tyrosine hydroxylase, which is a copper-dependent enzyme. It is known, however, that epinephrine and norepinephrine are decreased in animals that are deficient in copper (II). In ruminants, copper is shown to be necessary for myelination of nerves and for the maintenance of normal skin pigmentation (33, 61),... 

Although the sterols of normal adult brain are accounted for almost exclusively by free cholesterol, demyelination as a result, for example, of Wallerian degeneration or multiple sclerosis leads to a loss of cholesterol and the short-lived appearance of cholesterol esters (see Davison and Wajda, 1962). Other abnormalities of brain sterol composition are seen in the swayback lamb and in cerebral tumor tissue. 

A. Changes in Cholesterol Content of Swayback Lamb Brain... 

Swayback is a nonfebrile, ataxic disorder of newborn and young lambs. The disease is associated with a copper deficiency of liver and brain (Howell and Davison, 1959) and a resultant reduction in cytochrome oxidase activity of the brain (Howell and Davison, 1959). Both neuro-pathological and chemical examinations suggest that the lesion may be manifested in the white matter of the spinal cord by myelin aplasia (Table VI) (Howell et al., 1964). It was thought probable that reduc-... 

Free and Esterified Cholesterol in CNS of Normal and Swayback Lambs >... 

Anaemia, poor growth, depigmentation of hair and wool, swayback Pining (emaciation, anaemia, listlessness)... 

FIG. 7-1 (A) Kypholordotic posture. (B) Swayback posture. (C) Flat back posture. 

Ewes fed a diet deficient in copper may give birth to abnormal lambs (49, 50). The newborn lambs are unable to stand to obtain milk from their dams. Those that can get up sway and collapse their hind quarters seem paralyzed ( Swayback ). The brains of the affected animals show areas of de-myelination in the white matter, which may be of microscopic size or appear as a gross cavity. In the spinal cord secondary degeneration of the motor tracts has been found (51). The incidence of this disease can be greatly reduced among the offspring, when the ewes receive salt licks with copper supplements. 

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