180 INDIGESTION. 



connection of disorders of the omasum ^Yitll febrile and inflammatory 

 diseases. 



Food is an important cause. Impaction of the omasum is a winter 

 disease — the time of dry feeding. Dry, fibrous, innutritions fodder, and 

 scarcity of water contribute to its production. It attacks cattle in spring 

 or autumn on pastures in which fresh grass grows among the dead, 

 dried, or withered stems of a previous growth. It occurs when stock 

 are fed on corn or corn stalks (maize stalks) affected with smut or ergot, 

 or on cereals or grasses similarly damaged, and in both cases especially 

 when the water supply is deficient or restricted. 



Sheep and goats, which habitually drink little, suffer less than do 

 cattle, which drink freely. 



Other causes. Fermented foods, microbian ferments and their pro- 

 ducts, which tend to induce torpidity of the omasum, fever, and lessened 

 secretion of saliva, with diminished supply of liquid from mouth or rumen. 



Pericarditis, by causing vascular stasis m the omasum, may induce 

 torpor and imj^action. 



Lead poisoning paralyses action and favours impaction. Finely 

 divided food stuffs — meal and bran — eaten greedily, may pass in quantity 

 directly into the omasum and induce impaction. " The most acute and 

 fatal forms occur in connection with a sudden change from dry to rich, 

 luscious, green food in spring, the unwonted stimulus giving rise to 

 ■ general irritation of the whole gastric mucosa, with disordered and im- 

 paired function of all four stomachs, but especially of the third. Such 

 cases are usually congestive and inflammatory, and the suspension of the 

 gastric movements is a grand cause of impaction. In such cases, too, 

 the brain or spinal cord, or both, are seriously involved, and the early 

 death is preceded by torpor, paralysis, violent delirium or convulsions, 

 following largely the type of acute lead poisoning." (Law, loc. cit.) 



The symptoms depend on the degree of impaction, and vary from 

 simple, irregular, or suspended rumination to severe gastric and nervous 

 disorder. The less acute cases are marked by failure to re-establish 

 regular rumination or partial convalescence from fever or inflammation. 

 The fever subsides, but the appetite remains capricious, the muzzle dry, 

 eyes dull, spirits low, and breathing accelerated ; the condition is some- 

 times accompanied by moaning. Slight tympanites may appear, and 

 the contents of the rumen may feel solid, the mouth hot, clammy, and 

 foetid. The bowels are constipated, the fftces small in quantity, hard, 

 covered with mucus or blood- streaked, and containing particles of undi- 

 gested food ; in other cases diarrhoea may set in, to be followed later by 

 constipation. Alternations of constipation and diarrhoea may be repeated 

 again and again. Exploration by pressure of the closed hand over the 

 omasum will give an impression of solid resistance. There may be slight 



