85 



intense redness of the mucous membraue of the eyes, and increased 

 pulse-beat are characteristics of this stage. The head is generally held 

 in a peculiar position, either stretched at length, turned backward, in- 

 clined to either side, or drooped. The intensity of these symptoms 

 depends ou the number of invading parasites. Later, spasmodic con- 

 vulsions or paralysis may occur. Death may take place in about six 

 or eight days after the first symptoms are noticed. The diagnosis at 

 tills stage is difficult, but depends on finding the parasites and their 

 channels on the surface of the brain. The former are at this time the 

 size of a mustard or flaxseed. A correct diagnosis at this stage will 

 influence the future treatment of the flocks. If the sheep live through 

 this stage no further symptoms will be noticed for from four to six 

 months, when a new set of symptoms will appear. It is said that of all 

 infected sheep less than 2 per cent, of those which show the disease in 

 the early stage recover. 



The symptoms of the second stage arise from two causes — from the irri- 

 tation produced by the little heads thrust out of the mother bladder 

 and frOm the disturbances created by the pressure caused by the in- 

 crease in size of the cwnurus. 



The actions from which the disease has derived its common name in 

 all countries are especially characteristic. The head turns ;. the animal ■ 

 walks in a circle; it staggers, trembles, has convulsions, acts stupid; 

 it becomes unable to eat or drink, and finally dies of exhaustion or pa- 

 ralysis. The various gaits and peculiar positions assumed by the infected 

 animals arise from the particular location of the parasite. The length 

 of time between the attack and death also depends on this position, 

 some parts of the brain being more vital than others. Death occurs in 

 a month or a month and a half after the secondary symptoms appear. 



A diagnosis of the disease in this stage can be determined by an ex- 

 amination of an infected animal. Sometimes at this stage the parasite 

 softens the wall of the skull by its continued pressure and the spot can 

 be felt with the fingers. Gcenuri in the spinal canal are more difficult 

 to diagnose. They cause the sheep to stagger and walk peculiarly with 

 the posterior extremities. Sometimes the disease is manifested by an 

 intense itching along the backbone without any apparent reason. Paral- 

 ysis of the hind limbs and of the rectum and bladder often result. 



The gid should not be confounded with the disease caused by grubs 

 in the nasal cavities, which sometimes produce similar symptoms. The 

 false gid produced by the larvaj of the CEstrus ovis will cause more symp- 

 toms of a catarrh or cold in the head and less of the turning, which is 

 so very characteristic of true gid. 



Treatment. — There is no treatment that can be profitably followed for 

 sheep thus affected. A veterinarian could in the more advanced cases 

 locate the position of the cyst either by inference from the character of 

 the symptoms or by feeling the softened spot in the craninm. He 

 might, by carefully cutting away or trephining the skull over the point, 



