ABSTRACT

The urinary system of the pig is anatomically similar to that of most species. The kidney of a 70 kg domestic pig is approximately the size of that of an adult human. In newborn pigs, the development of nephrons continues for approximately 3 weeks in contrast to the fully developed nephron system in humans at birth. The kidneys of a 25 kg Hanford miniature pig weigh 120 g and measure 11 × 6 × 3 cm which is similar to the human (Schwalb et al., 1989). In these minipigs, the ureteral length is 22-26 cm with a diameter that accommodates a 4-6 French (Fr) catheter and a bladder capacity of approximately 150 mL. The left kidney is more cranial than the right kidney and its cranial pole is located at approximately the 13th rib (L1-L4). The renal artery and vein divide into two branches close to the renal hilus. The blood supply is divided into cranial and caudal segments rather than into longitudinal halves as in other species. This means that the avascular plane of the kidney is transverse rather than longitudinal (Figures 7.1 through 7.3). Renal blood ow is reported as 365 mL/ min and medullary blood ow as 2.5-2.6 mL/min/g (Lüdemann et al., 2009). There are some differences in anatomy and function between the pig and human (Tables 7.1 through 7.4), even though the internal renal anatomy is very similar (Figure 7.4). The multirenculate, multipapillate kidney of the pig contains a greater proportion of juxtamedullary glomeruli, the loops of Henle are relatively longer, and creatinine is absorbed from the proximal tubule (Figures 7.4 through 7.6). Maximum urine concentration in the pig is 1080 mOsm/kg, which compares favorably to that of the human, which is 1160 mOsm/kg. The calyx contracts approximately 15 times/min and the renal pelvis 3-6 times/min in both the pig and human (Assimos et al., 1986; Deding et al., 2006; Friis, 1998; Giraud et al., 2011; Sampaio et al., 1998; Schwalb et al., 1989; Swindle and Olson, 1988; Dalmose et al., 2000; Terris, 1986). Danish Landrace pigs 9-13 weeks of age (12-18 kg) were extensively studied for normal urine production (Deding et al., 2006). Urine production was approximately 15 mL/kg/h during the daytime and approximately 8 mL/kg/h at night. Daytime voidings peaked around noon and were approximately 15 during the day and 3 during the night with a mean of 18.7 voidings. The mean total volume was 2845 ± 900 mL. Average urine ow was approximately 12 mL/s and residual urine was variable between 0 and 136 m. Their average uid intake was 4151 ± 1313 mL.