URINARY ORGANS OF THE DOG 569 



The weight of the kidney of an adult pig is about seven to nine ounces (200 to 

 250 grams). The ratio of their combined weight to that of the body is about 

 1 : 150-200. The length in an adult of good size is about five inches (ca. 12.5 cm.) 

 and the greatest width about two and a half inches (ca. 6-6.5 cm.). 



Structure. — The hilus is about in the middle of the medial border. The pelvis 

 is funnel-shaped, and divides into two calyces majores, which pass in a curve for- 

 ward and backward respectively, and give off some eight to twelve short calyces 

 minores; each of the latter contains a papilla. Some papillae are narrow and coni- 

 cal, and correspond to a single pyramid; others are wide and flattened, and result 

 from the fusion of two or more pyramids; some project directly through the wall 

 of the renal pelvis without the formation of a calyx. The renal pyramids are dis- 

 tinct, but it is apparent that some are compound, i. e., formed by fusion of primi- 

 tively separate pyramids. The renal vessels enter the ventral part of the hilus, 

 and the ureter leaves it dorsally. 



The adrenals are long and narrow. Each lies along the medial border of the 

 corresponding kidney from the hilus forward; they are in contact medially with the 

 crus of the diaphragm and the posterior vena cava. 



The only special features in regard to the ureter are that it is at first relatively 

 wide and gradually diminishes in caliber, and that it is slightly flexuous. 



The bladder is relatively very large; when full, it lies chiefly in the abdominal 

 cavity. The dorsal surface is almost completely covered with peritoneum, but 

 the serous covering does not extend so far back ventrally. 



URINARY ORGANS OF THE DOG 



The kidneys (Fig. 624) are relatively large, forming about xrs" to ^i'o oi the 

 body-weight; the weight of the kidney of a medium-sized dog is about two ounces 

 (ca. 50 to 60 grams). They are both bean-shaped, thick dorso-ventrally, with a 

 rounded ventral surface and a less convex dorsal surface; the surfaces are smooth. 



The right kidney is not subject to much variation in position; it is situated 

 usually opposite to the bodies of the first three lumbar vertebra, but may be as far 

 forward as the last thoracic. Its anterior half or more lies in the deep renal im- 

 pression of the liver ; its posterior part is related to the sublumbar muscles dorsally, 

 and the right branch of the pancreas and duodenum ventrallj^ 



The left kidney is subject to some variation in position; this is due to the fact 

 that it is loosely attached by the peritoneum, and is affected by the degree of ful- 

 ness of the stomach. When the stomach is nearly empty, the kidney usually 

 corresponds to the bodies of the second, third, and fourth lumbar vertebrae, so that 

 its anterior pole is opposite to the hilus of the right kidney; exceptionally the 

 anterior pole may be opposite the posterior end of the first lumbar vertebra. When 

 the stomach is full, the left kidney is usually the length of one vertebra further back, 

 so that its anterior pole may be opposite the posterior pole of the right kidney. 

 The dorsal surface is related to the sublumbar muscles. The ventral surface is in 

 contact with the left part of the colon. The lateral border is related to the spleen 

 and the flank. The anterior extremity touches the stomach and the left extremity 

 of the pancreas. 



The lateral border of the left kidney usually has considerable contact with the flank, and 

 hence it may be palpated more or less distinctly in the living animal, about half-way between the 

 last rib and the crest of the ilium. But in some cases the spleen assumes an almost longitudinal 

 direction, thus intervening between the kidney and the flank. 



Structure. — The hilus is in the middle of the medial border and is relatively 



