The parasite. Scrapings from the abomasum and intestine when diluted with water and viewed under a lens show minute bodies resembling short, fine hairs. When isolated these are easily visible with the naked eye. In situ they appear to be lying on the mucous membrane, sometimes with the head fixed in the latter. They vary in length from ³⁄₂₅ to ⁶⁄₂₅ of an inch, and are brownish in colour. For a detailed description see Penberthy loc. cit. McFadyean (Jour. of Comp. Path. and Therap. for 1896, p. 314) also gives a very full description, illustrated by plates, of the two species of strongyles which he regards as the cause of gastritis in cattle in England.
Fig. 115.—Caudal extremity of male Strongylus cervicornis. (Block kindly lent by Prof. McFadyean.)
The lesions are those of wasting diseases. The first three gastric compartments may be thin, but usually show no abnormality. The mucous membrane of the abomasum shows evidences of catarrh, is sometimes covered with a loose croupous material, or is denuded of its epithelium and even extensively destroyed. In acute cases it is more or less deeply reddened over spots or extensive patches. Occasionally it appears jelly-like, owing to effusion into its substance. Except for the catarrhal condition the small intestines may be healthy, but the large, especially the colon and cæcum, show lesions similar to, but more pronounced than, those of the abomasum.
The treatment comprises administration of the usual vermifuges, of which Penberthy prefers turpentine. The diet should be nutritious and easily digestible. Among drugs, non-irritant iron salts, cod liver oil, bitter vegetable tonics and common salt are recommended. The animals should be housed and kept warm; the litter, containing parasites, should be destroyed. The pastures may be dressed with salt and lime; those worst infected should be ploughed. An uninfected water supply is essential.
Parasitic Gastro-enteritis in Sheep and Lambs. A disease in seven to eight months old lambs, closely resembling the above, was described by McFadyean in the Jour. of Comp. Path. and Therap. for 1897, p. 48. Sheep over one year old were not affected.
The symptoms comprised diarrhœa, rapid wasting, impaired appetite, thirst, a tendency to lick and swallow sand or earth, dulness, and continued fever (105° to 108° Fahr.). There was no evidence of acute pain or of marked cough.
Duration. The disease sometimes proved fatal in one or two days, but sometimes extended over several days or weeks. The mortality varied from 10 to 20 per cent., but in many cases almost all the members of a flock exhibited diarrhœa and loss of condition.
The cause appeared to be the presence of small nematode worms in the fourth stomach, which generally exhibited gastritis with inflammatory congestion of the mucous membrane, though in a considerable number of cases the lining membrane of the stomach was markedly anæmic. In a large number of cases the irritation of the mucous membrane was continued into the duodenum, but as a rule the remainder of the small intestine was not inflamed.
The worms named by McFadyean Strongylus cervicornis are from 10 to 12 mm. in length, so that although not of microscopic dimensions they cannot be seen when suspended in the stomach contents. They are readily detected in microscopical preparations under a low power.