664 MANAGEMENT OF SHEEP INTERNAL PARASITES 



ing absorption of the contiguous parts of that organ, and 

 usually a thinning and softening of the skull in one or other 

 of the hollows on the crown of the head immediately in front 

 of a line drawn between the ears, where the skull is compara- 

 tively thin. Partial paralysis accompanies the later stages of 

 the development of the malady, and the sheep becomes blind 

 on, and circles to, the side opposite that on which the cyst 

 inclines. 1 Boring with a trocar and cannula to break, or if 

 possible, to extract the " bleb " and its contents, is easy in 

 such a case. When the seat of the disease is far back in the 

 brain, the skull is thicker over the affected part, and there is 

 not sufficient time, before death is liable to occur, for the 

 bone to become thin and soft by absorption. In Scotland 

 this form of gid is known by the specific name of " thorterill." 

 Piercing then leaves little pieces of bone, fractured from the 

 skull, on the surface of the brain, which, although the disease 

 may be cured, produce within a few days suppuration, which 

 usually results in death. The late Principal Wm. Williams 

 recommended in place of a piercer the use of a trephine (a 

 little circular saw), to remove a minute round piece of bone. 

 The skin is bared from the skull immediately over the spot 

 to which the movements of the sheep direct suspicion. All 

 detached pieces of bone are washed carefully away before the 

 membrane covering the brain is broken. Piercing in the 

 usual way through the brain to reach the bag is then per- 

 formed with comparative safety. When the disorder is located 

 in the forehead, or in the case of rams with skulls too thick to 

 soften, the old remedy described by Youatt of passing a thin 

 skewer or sharp steel wire up the nostril and right into the 

 brain-box to reach and penetrate the water-bag, is the readiest 

 and most simple, and often effective, means for a shepherd to 

 employ. The wire is kept close up against the roof of the 

 nostril, and should be only stopped by the skull under the 

 forehead. After it has penetrated the skull, it should be 

 partially withdrawn and returned two or three times in a 



1 In some cases the animal walks straight forward with head 

 depressed, running against everything in its way, and frequently falling. 

 Then it is likely that the parasite is attached to the Corpus callosum; if 

 the animal walks straight forward with head elevated, sometimes reeling, 

 the parasite will be found on the Cerebellum, or in the fourth ventricle. 

 PENNINGTON. 



