Urinalysis can reveal much information about the health of an animal—in particular, regarding the status of carbohydrate metabolism, kidney and liver function, acid-base balance, and urinary tract infection. Urine was collected from habituated gorillas in the Parc National des Volcans, Rwanda to establish reference intervals for various physiological values. The urine was collected midstream as the animal urinated or from pools formed in the foliage. Sixty-six samples were collected between August 1996 and January 1997. Thirty-four midstream samples, including two collected during anesthesia, and nine samples from the foliage were of a quality sufficient to be included in the study. This represented samples from 16 males, eight females, and one of unknown sex, of which five individuals were juveniles. Multiple samples were collected from nine gorillas.
The color and turbidity were evaluated by visual observation. The pH, specific gravity, and presence of protein, glucose, ketones, bilirubin, urobilinogen, blood, and nitrate were evaluated using commercially available dipsticks (Combur 10 Test, Boehringer Mannheim, Mannheim, Germany and Ames Multistix 10 SG, Miles, Inc., Elkhart, IN, USA). The specific gravity was also determined using a handheld refractometer calibrated against distilled water. A portion of the samples with sufficient quantity was centrifuged for 5 minutes at 2000 rpm. The supernatant was removed, and an aliquot of the deposit was examined microscopically for the presence of cells, casts, crystalline, and other deposits. The color ranged from pale yellow to yellow (79% of samples), to dark yellow or brown (21%). The majority (88.3%) of samples were clear; the rest had varying degrees of cloudiness. The mean±SD specific gravity as measured by the refractometer was 1.013±0.003 (n=32), and the mean±SD pH was 8.45±0.42 (n=43). Eighteen out of the 43 samples (41.9%) had a trace of protein. Seven (16.3%) had a trace of leukocytes, and eight (18.6%) were positive for nitrite, four (9.3%) of which were positive for both tests. Three (7%) were considered to be low positive for bilirubin. All other samples were negative for the above tests. All samples were negative for glucose, blood and ketones, and all samples were considered to be within normal limits for urobilinogen. Thirty-three of the 37 samples (89.1%) examined microscopically contained some deposits in the urine. Twenty-nine (78.4%) samples contained varying amounts of crystalline material mostly suspected to be phosphate crystals, and 13 (35.1%) had varying amounts of amorphous deposits. Rare casts were seen in 12 samples (32.4%), and three (8.1%) had very rare epithelial cells.
From this study, it appears that it is feasible to collect urine from wild mountain gorillas for diagnostic purposes. The establishment of normal physiological values will hopefully improve the noninvasive diagnosis of disease in mountain gorillas and allow for prompt and effective treatment of individual gorillas with minimum disturbance to the population.