Book VII. 



PHYSIOLOGY OF THE HORSE. 



905 



urinary, and the spermatic, all which are invested by a membrane called the peritoneum, which, after 

 covering each of these organs separately, is reflected over the cavity of the belly itself. It is very strong, 

 and very elastic, as we perceive by the effects of dropsy, great fatness, and likewise by the increase in 

 pregnancy. The umentu?n or cawl (c) is the fatty apron which first presents itself on opening an animal's 

 body, extending in some, as 

 the dog, pig, &c., into the pel- 

 vis ; but in the horse it is less 

 considerable, by which he is not 

 subjected to cpislocele as they 

 are. Its uses are unknown. 



5727. The stomach and its di- 



festive functions. The horse 

 as one stomach only, and that 

 a very small one, drawing a 

 very wide line of separation by 

 this means between his family 

 and the ruminants. In fact the 

 stomach of tiie horse may be 

 regarded as intermediate be- 

 tween the triturating muscular 

 one of fowls, and the mem- 

 branous one of the graminivo- 

 rae. It is peculiarly constructed 

 to keep up this intermediate 

 character, being partly membra- 

 nous, partly muscular, and part.* 

 ly cuticular ; in which latter 

 formation much of its peculi. 

 arity consists, and which it 

 shares in common with asses, 

 rats, and mice ; whose habits 

 of living on grain give them a 

 like claim to this wise provision 

 In a state of rest, or only mode- 

 rately distended, its diroction is 

 across the abdomen, with its two 

 orifices directed upwards; but 

 the cardiac or recipient orifice, 

 to which the oesophagus is at- 

 tached, the most so ; while the 

 pyloric or expellent orifice is 

 rather lower, and more inclined 

 backward. The situation of 

 the stomach is imm.ediately 

 contiguous to the diaphragm 

 or great breathing muscle 

 iJig- 618 k k), from which we 

 are at no loss to understand why 



a very full meal obstructs respi- ^ ^ ^ 



ration ; and why it is so impru- /57y^'^////i^^^^^'^^^^^=^^^Mli^^^Hlliiliii8^^^^^i^^^^' 



dent to gallop a horse very hard ' ' ^ ^ 



after drinking or eating fully. 

 Small as the stomach is in a natu- 

 ral state, it is yet capable of great 

 distention, as has been witnessed in stomach staggers, when upwards of half a hundred weight of undi- 

 gested food has been extracted from it. The membranous portion of the stomach is gained from the peri- 

 toneum ; within this is situated its muscular part, principally composed of longitudinal and transverse 

 layers, by which its motions in digestion are regulated. Around the cardiac or recipient orifice, a strong band 

 of circular fibres is very evident, which effectually constringes this part, and prevents regurgitation or 

 vomiting in the horse, except under extraordinary circumstances of muscular relaxation and sympathy. 

 It has been already shown that the anterior part of the alimentary canal, as the mouth, throat, and gullet, 

 are lined with cuticle or skin. This cuticle is continued into the stomach, and lines nearly a half of its 

 internal surface, whose office seems to be a more perfect comminution of the food, which the horse has no 

 opportunity of remasticating like the ox, sheep, &c. The villous or sensible portion of the stomach is 

 thrown into folds, so as greatly to increase its surface : here the comminuted food in its passage becomes 

 saturated with the solvent gastric juice, and is then passed forward into the intestines. 



5728. The derangements of the stomach may be explained from its anatomy. Tliough small, and 

 its sensible parts still smaller, yet it is subject to more diseases, and to more frequent derangement than 

 is generally supposed. It has been proved to be muscular, and that its digestive functions are performed 

 by means of its muscularity. It has also been shown that the contractile energy of the muscular fibre, is 

 }nainly gained from the oxygen derived from the blood ; whatever tends to interrupt this separation, a 

 an unhealthy state of the lungs, too quick action of them, &c. must derange the action of the stomach 

 also. The perfection of its digestive powers is also derived from its secreting healthy gastric juice, 

 consequently whatever interrupts this process, must likewise interfere with stomachic health, and that 

 such health is more often impaired than is generally supposed, and that many ailments, attributed ta 

 other causes, are really dependent on an affection of this organ, experience and observation will fully 

 evince. Out of condition is a most frequent complaint among horsemen ; their horses are out of 

 condition, and unfit for work : the apjiearances are various, but are all well known ; yet it is seldom 

 considered, that it is owing in every seven cases out of ten, to the stomach being morbidly affected. 

 (5756.) It is evident that too full feeding must derange it, not only by keeping it constantly dis- 

 tended, and thus weakening its capacity ; but by entrenching too much on its secreting office, and 

 requiring an inordinate quantity of gastric fluid to saturate an undue quantity of farinaceous matter. 

 The bots, that are frequently found on its cuticular coat, and are there probably harmless, sometimes 

 displace themselves, and settle on the villous part, where they must occasion uneasiness and probable 

 inflammation. 



5729. The intestines {fig. 616 k, l) in the horse may be considered not merely as secerning organs 

 alone, as in man and many animals, but as really digestive organs, and continuations of the sto- 

 machic viscer" This is more particularly the case with the small intestines, and may therefore 

 entitle them to the term of alimentary canal, and the large to that of the excremental ; the for- 

 mer measure from twenty-one to twenty-three yards in length, and the latter from seven and a half 

 to eight yards and a half, according to the size of the animal. The duodenum is the first of the 

 maU intestines, commencing at the pyloric orifice of the stomach ; the jejunum, which is the next and 

 larger portion, and the ilium {fig. 616 e), which is still longer, form the remainder. The alimentary 



