Urine sediment characterisation in physically healthy adult jennies (Equus asinus). A cross-sectional study.

Overview

• This study characterizes the urine sediment and establishes urine specific gravity reference values in healthy adult female donkeys (jennies), providing baseline data to improve urinalysis interpretation in this species.
• The researchers also propose an initial grading system to semi-quantitatively evaluate urinary sediment components in donkeys.

Introduction

• Urinalysis is a key, non-invasive diagnostic tool used to assess kidney and urinary tract health.
• Despite its importance, detailed information about normal urinary parameters in donkeys (Equus asinus) is limited compared to horses.
• Donkeys have physiological differences from horses, which can affect urinalysis results, so species-specific reference intervals are needed.
• This study aims to fill that gap by analyzing urinary sediment and specific gravity in healthy adult jennies.

Methods

• Population: 54 healthy adult female donkeys (jennies) were selected.
• Sample collection: Urine collected via catheterisation to avoid contamination, ensuring reliable sediment analysis.
• Analyses performed:
• Refractometry to measure urine specific gravity (USG).
• Dipstick testing for biochemical parameters such as leukocytes, glucose, and erythrocytes.
• Microscopic examination of the urine sediment to identify and quantify elements such as crystals, cells, and casts.
• Development of a preliminary semi-quantitative sediment grading scale based on sediment composition.

Results

• The median USG was 1.048, with an interquartile range (IQR) of 1.040 to 1.055, indicating concentrated urine similar to horses.
• Urine pH median was 7.6 (IQR 7.2–8.0), suggesting slightly alkaline urine.
• Dipstick analysis showed absence of leukocytes and glucose, indicating no infection or glucose spilling.
• Only one sample contained erythrocytes, indicating negligible red blood cells in healthy jennies.
• Urine sediment findings:
• Calcium carbonate crystals were present in all samples, indicating a common physiological presence in donkey urine.
• Calcium oxalate monohydrate crystals were found in 74.07% of samples, which may also be normal in donkeys.
• Mucus filaments were observed in 66.67% of the samples, potentially originating from urinary tract lining.
• Epithelial cells were seen in 57.41% of samples, normal as some cell shedding occurs.
• Granular casts appeared in 27.77% of samples, and hyaline casts in 7.41%, both types of urinary casts that can appear in healthy animals though their prevalence varies.

Discussion

• The urine specific gravity values observed in healthy jennies are comparable to those reported in horses, supporting similar renal concentrating ability between species.
• The universal presence of calcium carbonate crystals suggests they are a normal finding in donkeys and not necessarily indicative of pathology.
• The frequent observation of calcium oxalate crystals, mucus filaments, epithelial cells, and casts provides a baseline sediment profile aiding in recognizing normal versus abnormal findings.
• The development of a sediment grading scale offers a systematic approach for semi-quantitative evaluation of sediments, which is useful for clinical and research purposes.
• These data improve understanding of donkey urinary health, helping veterinarians interpret urinalysis results more accurately in this species.
• Future work should validate and refine the proposed grading system and expand reference intervals for other urinary parameters.

Conclusion

• This study establishes normative data for urine specific gravity and sediment composition in physically healthy adult female donkeys.
• It confirms similarities with horses in certain parameters while highlighting unique sediment characteristics such as consistent calcium carbonate crystals.
• The preliminary sediment grading scale could standardize urinalysis interpretation in donkeys pending further validation.
• Overall, the research provides valuable baseline information to enhance diagnosis and monitoring of urinary health in donkeys.