Dilatation of the Gall- Bladder. 535 



Apart from the general causes of melanosis, benignant or 

 malignant, no definite reason for this pigmentation has been 

 assigned. The development of melansemia and tissue pigmenta- 

 tion in man from malarious microoganisms suggests that other 

 germs and their products may have a similar effect in the lower 

 animals but nothing certain is known as to the true cause. 



Apart from melanosis, it is not known that this pigmentation 

 of the hepatic cells is of any essential pathological importance. 

 It is important however for the veterinarian to be acquainted with 

 the condition, that he may intelligently deal with such lesions 

 whether seen in ordinary post mortem examinations, or in the 

 course of meat inspection. 



DILATATION OF THE GALL BLADDER .AND BILE 



DUCTS. 



Causes : obstruction of common bile duct, distoma, round worms, 

 taeniae, gall stones, encrustrations, inflammations, tumors, cicatrices, hy- 

 datids. Congenital absence. Ducts stand out on liver. Symptoms of 

 colic, icterus, bile poisoning, marasmus. Treat the causative conditions. 



This may occur in all our domestic animals except solipeds in 

 which latter there is no gall bladder. 



Causes. Any serious obstruction to the discharge of the bile 

 into the duodenum may cause it. The presence of trematodes, 

 nematodes, or even taeniae in the ducts, gall stones, incrusta- 

 tions, occlusion of the ducts by inflammatory swelling, tumors of 

 the liver or adjacent parts, echinococcus, cysticercus, or cica- 

 trices may be cited. Cadeac mentions a case of congenital 

 atresia of the bile duct in the calf. Vigney records a case in the 

 cow in which the greatly dilated gall bladder formed a hernial 

 mass in the epigastric region which was, however, easily reduced 

 by manipulation. 



In all such cases the distended bile ducts stand out as white 

 branching lines on the back of the liver converging toward the 

 portal fissure. The walls of the ducts may be attenuated or 

 thickened and it is alleged calcified. They are usually lined by 

 a deposit of cretaceous consistency precipitated from the retained 



