Trembling in Sheep, etc. 505 



or trembles violently. If merely raised or disturbed the trembling 

 or clonic spasms are very marked, the nose is jerked forward and 

 upward from the contraction of the muscles attached to the occi- 

 put ; the legs may be lifted jerkingly as in stringhalt ; when 

 raised they are moved stifHy or sway uncertainly before the foot 

 is once more planted ; or the sheep loses its balance, falls to the 

 ground and struggles convulsively in its efforts to get up and 

 escape. As the result, it will in certain cases jump to its 

 feet, rising meanwhile to an undue height in the air. In other 

 cases there is squinting or rolling of the eyes, and movements of 

 the jaws with frothing from the mouth. Or the spasms may be 

 tonic affecting especially the muscles of the back and loins, and 

 causing extreme stiffness or rigidity or even opo.sthotonos. Lambs 

 are unable to suck. 



But whether the early spastic symptoms are well marked or 

 not, paresis and even paralysis set in sooner or later. This usually 

 begins as paraplegia, or exceptionally one limb only may be 

 affected at first, causing the animal to walk on three legs. For a 

 time the fore limbs may be free, and the patient attempts to move 

 by dragging the hind limbs, which are extended backward. 

 When the fore limbs become involved the animal remains down 

 helpless and after awhile apathetic. Temperature and sensibility 

 are both greatly lowered in the paralyzed limbs. Sometimes the 

 spasms are lateral and the head may be drawn to one .side. 



In the animals that survive the early attack, there is likely to 

 remain some lasting deformity, such as wry neck, arched back, 

 stiff or swollen joints. Abscesses, which appeared in the inocu- 

 lated rabbits after a lapse of four months, are a not uncommon 

 sequel in sheep, the pus collecting in the neighborhood of a joint, 

 or of the lymph glands of the axilla, inguinal region, breast or 

 shoulder. 



The succession of symptoms are in the main such as are ob- 

 served in other cases of myelo-meningitis, first . exalted function 

 and later depressed and abolished. 



Diagnosis. From other forms of myelo-meningitis it may be 

 distinguished by its enzootic occurrence on tick-infested pastures, 

 which already have a reputation for causing this malady, by its 

 appearance only in the season of the development of the tick, by 

 the presence of the tick or of its sores on the skin, and by its 



