IMPACTION OF THE OMASUM (THIRD STOMACH). 179 



not be completely emptied, as there is danger of collapse of its walls. 

 Complications in the region of the wound can be avoided by drainage. 



If the operation succeeds, the patients must be placed on very low 

 diet or on milk for some days, and should be given lukewarm farinaceous 

 drinks, and a little hay of good quality to excite rumination. In old 

 milch cows this operation is seldom followed by a satisfactory recovery. - 

 Apart from the loss of milk, the animal loses condition, refuses to feed, 

 and gradually succumbs to exhaustion. 



IMPACTION OF THE OMASUM (tHIRD STOMACH). 



Definition. "A form of indigestion, of which the prominent feature 

 is the drying and impaction of the ingesta between the folds of the third 

 stomach. It may seem to be a primary disease, but in very many cases 

 it occurs as a result of some acute febrile or inflammatory affection." 

 (Law's " Veterinary Medicine," Vol. 11. p. 123.) 



Synonyms. Dry murrain, clew-bound, fardel-bound, stomach stag- 

 gers, grass staggers, vertigo, chronic dyspepsia, chronic indigestion. 



Causes. Torpidity of the omasum, suppression of salivary secretion, 

 with absence of " waves of liquid floating the finely divided food from the 

 mouth or rumen to third stomach, are prime conditions of desiccation of 

 the contents." The third stomach, like the first and second, has no pro- 

 vision for liquid secretion, and depends for its supply on constant flush- 

 ing by swallowed fluids. Therefore, if feeding and rumination are 

 arrested and salivary secretion is suppressed, and if movements of the 

 rumen and resulting overflow into the third stomach are checked, the 

 ingesta of the third stomach, compressed between its folds, becomes 

 drained of liquid and converted into a powder or dry mass. All febrile 

 and inflammatory affections tend to this end, and more or less drying, 

 with impaction of the contents of the omasum, is a constant feature in 

 such cases. But in the majority of cases this condition is to be looked 

 on as a secondary or subsidiary affection, and the real disease must be 

 sought elsewhere. 



The explanation of the susceptibility of the third stomach in consti- 

 tutional troubles has been sought in the source of its innervation. Electric 

 stimulation of the vagus rouses the movements of the first and second 

 stomachs, but not those of the third. Action of the third stomach is 

 excited by stimulation of the spinal cord, and of the synii^athetic nervous 

 branches going to the ganglionic cells in the walls of the omasum (Colin 

 and Ellenberger). Its nerve supply _coming from a different source, de- 

 rangement of its function may occur independently of antecedent disorder 

 of the first or second, and its motor supply coming from a source so closely 

 related to the vaso-motor centres, perhaps affords some explanation of the 



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