Leaflets. Nos. 101 to 200 / Board of Agriculture and Fisheries.

  • Great Britain. Board of Agriculture and Fisheries.
Date:
1919
Catalogue details

Licence: Public Domain Mark

Credit: Leaflets. Nos. 101 to 200 / Board of Agriculture and Fisheries. Source: Wellcome Collection.

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    gradually increases in size and brings about the symptoms by which the disease is usually recognised. The cyst, which is the sole cause of “gid,” is a little bag of variable size, and though originally very small, may in two or three months become as big as a hen’s egg. Its outer coating is very thin, and it is more or less expanded by a clear colourless liquid. The parent cyst develops on its surface 100 to 200 little chambers like white spots about the size of a millet seed, and each contains the head of a future tapeworm. They cannot develop further till the sheep dies, and the brain or the part containing the cyst is eaten by a dog. When this happens each little worm-head is set free from the cyst by the digestive juices. It becomes fixed to the wall of the intestine, and grows for about 24 months, when the segments are passed out on to the grass in the manner which has already been described. Symptoms. A sheep affected with gid may be excitable, and very timid when approached, or it may be dull and stupid. Usually it is seen apart from the rest of the flock walking about unsteadily. Frequently it turns round in a circle. It is seldom at rest for any length of time and if disturbed may try to run away, but it can only move helplessly round in one direction, often with its head carried unevenly on one side. In advanced cases the sheep may become blind. If the cyst exist in the usual place near the surface of the brain and on one side, the animal usually walks round to that side; if a cyst exists on both sides it may circle to one side or the other at different times; if it be situated in the fore part of the brain, the sheep raises its nose and walks straight forward, only stopping as a rule when it knocks up against something; whilst if the cyst is lodged in the back of the brain, the head is raised and the sheep stumbles forwards with a jerking uncertain motion of its limbs, breaking into a sort of shambling run ending in a fall and a violent struggle to get up. If there be several cysts in various parts, the abnormal movements vary. In the course of time the affected sheep refuses to eat, and by the combined effects of starvation and almost constant movement it rapidly wastes away and dies. The sheep may live for about six weeks after the appearance of well- marked symptoms. The cyst may be lodged in the spinal cord, usually at the region of the loins. In this case weakness and drooping of the loins is noticed. Eventually the sheep becomes com- pletely paralysed in its hind quarters, which it cannot raise