Symptoms. 1117 



Thrombosis of the posterior vena cava causes similar changes 

 in the hindquarter, with which abdominal dropsy is associated 

 if the location of the obstruction is between heart and liver. 

 Thrombosis of the portal vein impairs the motility of stomach 

 or intestine (Vol. 11. ). 



The circulatory disturbances may occasionally become much 

 lessened, as was shown in a case of Albrecht 's and in one of the 

 author's. 



Literature. Albrecht, Z. f. Tm., 1902. VI. 428 (Lit.). — Barrier, Bull., 

 1906. 283. — Basset, Eec, 1905. 609. — Bretagnier, Eec, 1909. 156. — Chouleur 

 & Lebasque, Bull., 1908. 256. — Cuny, J. vet., 1906. 224. — Douville, Bull., 1907. 

 62. — Forgeot, J. vet., 1906. 362. — Friedrieh, B. t. W., 1905. 4. — Petit & 

 Delacroix, Bull., 1905. 133. 



5. Rupture of the Large Blood Vessels, Ruptura Vasorum. 



The walls of the large blood vessels rupture at times, even 

 without previous disease. The lirst segments of the aorta and 

 of the pulmonary artery are very thin at the level of the semi- 

 lunar valves (the aorta of the horse is in some places only 1 mm. 

 thick, while lower down the thickness is 5-7 mm.), so that they 

 are bulged out somewhat by the pressure of the blood, even 

 under normal conditions (Sinus Valsalvae) and may rupture 

 if a sudden rise in blood pressure occurs. Among causative 

 factors, aside from immediate injuries, may be mentioned the 

 pulling of heavy loads, severe exertion in galloping, vomiting, 

 labor pains (Sigl) or other exertions. Similar causes may some- 

 times lead to rupture Of the anterior or posterior vena cava or 

 of the portal vein. 



Usually, however, rupture is preceded by a disease of tlie 

 vessel wall, although this may not be visible to the naked eye, 

 as in a case of Caparini's. In most cases there is a sclerosis 

 with subsequent bulging of the vessel wall, which favors rupture. 

 This cause is responsible for the rupture of vessels, especially 

 in older animals. The same result is observed if an abscess or 

 ulcerating process in the immediate vicinity of the vessel is 

 transmitted to the vessel wall from an ulcerating valve, a cari- 

 ous bone, or from a breaking down new growth, causing 

 erosion of the vessel. Finally animal parasites, in the horse 

 the larvae of Sclerostomum vulgare, in the dog Spiroptera san- 

 guinolenta may weaken the vessel wall so much in places that 

 it finally tears under the influence of the blood pressure. 



The following facts may illustrate the manifold etiological factors: Palat 

 saw rupture of the aorta at the level of the valves without demonstrable external 

 caui-e, Lustig saw it occur on galloping. ISequens found in three cases the point 

 of rupture about 1 cm. above the valves in the vicinity in which the vessel wall 

 was diseased, but Cadiot could not find any pathological changes in two cases. 

 In one case described by Vaerst hemorrhage occurred from a small aneurysm 

 situated opposite the valves. — In a case reported by Prietsch the healthy pulmonary 

 artery was ruptured while drawing a heavy load. Block saw a four-your-old stallion 

 bleed to death after having been thrown; the pulmonary artery was torn at the 



