Skeletal muscles of sheep, with special reference to scrapie disease

Abstract

This thesis describes an attempt to find out if specific changes occur in sheep affected with scrapie. In the expectation that a detailed study of a narrow field would be sore productive than a study of many organs or systems, the work was limited in scope and represents but a small part of the broad, many-faceted approach to scrapie being conducted at the Moredun Research Institute.

An essential part of the investigation involved the examination of the sensory and motor innervation of muscles from scrapied sheep. It seemed not unreasonable to suppose that changes at the myoneural junction might provide an explanation for the occurrence of ataxia in cases in which degenerative cord and muscle changes were negligible.

Such a lesion could also explain the atrophy seen in cases of scrapie.

To determine the range of peripheral motor nerve changes that would be detectable and also to evaluate the efficiency of the examination methods used, denervation experiments were carried out on guinea pigs.

This series provided information which was of value in the interpretation of the motor end plate changes encountered In sheep.

The blood vessels, a major component of muscles, were also examined In some detail. In the course of a preliminary Investigation It appeared that sorapied sheep might have a higher incidence of intramuscular arterial abnormalities than non-scrapied sheep. Since no comprehensive data on the pathology of the vascular system of sheep could be found, an investigation into the condition of the more numerous and accessible visceral arteries was initiated. The results of this survey and a consideration of the pathology of the intramuscular arteries are included in this report.