Figure 1 . The urinary system of a female dog . From Sanderson [ 2 ] .
Figure 2 . The urinary system of a male dog . From Sanderson [ 2 ] .
Figure 3 . The urinary system of a female cat . From Sanderson [ 2 ] . Figure 4 . The urinary system of a male cat . From Sanderson [ 2 ] .
Upper urinary system
Kidneys
The kidneys are paired organs that sit within the retroperitoneal space in the dorsocaudal abdomen . They lie just under , and are closely attached to , the lumbar hypaxial muscle . The right kidney sits slightly more cranially than the left . The kidneys receive around 25 % of resting cardiac output and filter approximately 20 – 25 % of plasma [ 3 ] .
The functions of the kidney include eliminating hormones , toxins , drugs and nitrogenous waste ( urea ) through the formation of urine , maintaining salt concentrations through osmoregulation , and the release of erythropoietin to stimulate red blood cell production in the bone marrow .
The kidneys are involved in regulating blood pressure by secreting vasopressor agents and / or hormones . They also regulate the pH of the blood – predominantly by reclaiming bicarbonate from glomerular filtration – as well as regulating vitamin D activity and calcium levels .
52 Veterinary Nursing Journal