Baseline urinalysis values in common bottlenose dolphins under human care in the Caribbean

Abstract

Urinalysis is a rapid, simple, inexpensive, and reliable test that documents urine abnormalities reflecting various types of renal, hormonal, or metabolic diseases. Urinalysis could assist proper monitoring of the health of dolphins under human care; however, normal baseline values for dolphin urinalysis have not been reported, to our knowledge. We sampled urine from 193 common bottlenose dolphins (Tursiops truncatus), living under human care in 24 Caribbean dolphinariums, by voluntary free-catch and analyzed the urine for chemical and microscopic variables using multi-agent dry reagent chemistry dipstick test strips, dedicated pH reagent strips, and unstained sediment slides. Most urine was clear, pale yellow to dark yellow, and had a fishy odor. Dipstick glucose, bilirubin, ketones, and nitrites were negative in all dolphins. The urine pH was acidic (x ± SD; 5.88 ± 0.58) and specific gravity (SG) was 1.035 ± 0.008. Most animals had 0-2 red blood cells and white blood cells per 40× field, and were negative for proteins. On microscopic sediment, 42.7% of samples had few-to-many squamous epithelial cells; hyaline and epithelial casts were observed only rarely. Crystals were observed in 36.6% of the samples; most were calcium oxalate dihydrate (48.2%) and amorphous urates (42.4%). The values obtained in our study can be used as a reference for health monitoring of dolphins in dolphinariums, and to monitor renal conditions and function in dolphins being rehabilitated or under human care.

Urinalysis Reference Intervals between Rough-Toothed Dolphins (Steno bredanensis) and Common Bottlenose Dolphins (Tursiops truncatus) Kept Under Human Care

“…All 22 dolphins were trained to provide urine on command using positive operant conditioning, as described in Jiménez-Zucchet., et al [12]. The specific medical behavior steps were station, roll-over, maintenance of the genital slit above the water level, cleaning and drying the genital slit, and massage of the pubic area (Figure 1).…”

“…A sterile 3-ml transfer pipette was used to collect the sediment, transfer it to a microscope slide, and cover it with a coverslip. as none (0), rare (1-5), few (6)(7)(8)(9)(10), some (11)(12)(13)(14)(15)(16)(17)(18)(19), or many (>20). If casts, bacteria, or crystals were present, each type was also noted on the datasheet.…”

“…Diagnostic methods for common bottlenose dolphins have been developed, particularly hematology, blood chemistry, gastric sampling, and fecal cytology [11]. Nevertheless, it was not until 2019 that the baseline parameter of urinalysis was published for the first time for the common bottlenose dolphins, as urinalysis was rarely used as a diagnostic tool in these and other cetaceans [12].…”

“…Following, a URS-10 urine reagent strip (Teco Diagnostic, Anaheim, California), a pH-specific dipstick (HealthyWiser, Cheyenne, Wyoming), and a veterinary refractometer for determination of specific gravity were used for the examination. Jiménez-Zucchet., et al [12] demonstrated that in dolphins, the Aim-Strip 10-SG (Germain Laboratories, San Antonio, Texas) urine strip presented elevated acidic pH levels and that the HealthWiser dipstick results were more accurate. The URS-10 was inserted into the tube to measure glucose, bilirubin, ketone, specific gravity, blood, pH, protein, urobilinogen, nitrite, and leukocyte.…”

Rhabdomyolysis, myoglobinuric nephrosis, and crystalline nephropathy in a captive bottlenose dolphin

“…These have been reported in cetaceans with neutral-to-acidic urine conditions. 16 These crystals are known to take various shapes, 9 appearing as colorless to yellow-brown 21 birefringent crystals. Renal oxalosis delayed recovery in AKI human patients in one study and was postulated to have exacerbated the severity of the lesion.…”