DISEASES DUE TO INTERNAL PARASITES. 205 



control of the posterior limbs, or an intense itchiness may be 

 present along the backbone, and complete paralysis of the pos- 

 terior portion of the body involving the bladder and rectum fre- 

 quently takes place. 



A disease which resembles gid to a certain extent is caused 

 by grubs in the nasal and frontal cavities, produced from the 

 larvae of the gad-fly. It will be recognized, however, by the 

 Symptoms of catarrh and sneezing, and lack of the violent move- 

 ments seen in gid. 



Crcattnent. 



This is preventive to a great extent and consists in adminis- 

 tering vermicides to the dogs which inhabit the farm where 

 the sheep are kept, especially the sheep-dogs, and keeping the 

 sheep where they are not so liable to pick up the eggs voided by 

 dogs belonging to other parties. The heads of affected sheep 

 should -on no account be fed to dogs, but should be burnt or 

 otherwise effectually destroyed. These precautions, while they 

 would not entirely stamp out the gid on account of other ani- 

 mals, such as foxes, wolves and coyotes being bearers, they will 

 lessen the trouble to a great extent. Experience shows that with 

 a better general care of sheep, gid is less frequently observed at- 

 tacking them. Gid attacks appear to be more frequent in ani- 

 mals which have been exposed to inclement weather, which hag 

 a tendency to weaken the nervous system, the resulting debility 

 making them more prone to attack. When one or more cases 

 occur in a flock, it is permissible to suppose that a number have 

 been invaded at the same time, in which event any animal 

 which is fat, and shows the slightest indication of gid, should be 

 sold to the butcher. Where treatment is to be tried, the oper- 

 ation of trephining the skull and puncturing the sack is per- 

 formed. This allows the escape of the contents of the cyst, and 

 in some cases where only one cyst is present it has been known 

 to be successful. 



