Reference ranges and reliability of transabdominal ultrasonographic renal dimensions in thoroughbred horses.

This study aimed to establish a normal size range for kidneys in thoroughbred horses, based on ultrasound scans. The results showed that ultrasound was a reliable method for this purpose, and that kidney size tended to be consistent within this breed of horses.

Objective of Study

The research targeted to establish a normal size range (mean ± 2 standard deviations) for the kidneys of Thoroughbred horses and to evaluate the reliability of measurements taken through transabdominal ultrasonography. This study involved seven Thoroughbred horses.

Methods

• Ultrasound scans were obtained from each participating horse for three consecutive days, from different areas: intercostal space and the left paralumbar fossa.
• Measurements of the kidney’s length, width, and thickness, as well as of the cortex, medulla, and pelvic dimensions were taken.
• Two observers unaware of previous measurements took these readings to test the reproducibility of the procedure.
• The same measurements were taken on three separate occasions to evaluate short-term repeatability.
• The images produced by both operators were compared to assess the consistency of the images.

Findings

• The left kidney was consistently spotted in the same area – the left 15th to 17th intercostal space and the paralumbar fossa.
• The longest length (maximum) was found in the 16th intercostal space (12.7 ± 2.0 cm) and the maximum width in the paralumbar fossa (7.9 ± 1.1 cm).
• The right kidney was consistently found in the right 15th to 17th intercostal space with maximum length and width at the 15th intercostal space (16.0 ± 0.7 cm and 7.9 ± 1.0 cm respectively).
• The reproducibility of the measurements, the consistency of the images and the repeatability of the measurements were generally good to excellent, except for the smaller structures which showed less good results.
• No differences in kidney sizes between the horses were spotted.

Conclusion

The study concluded that renal ultrasonography is a reliable method for measuring kidney sizes in Thoroughbred horses. A reference range was set up. The research also found that renal dimensions vary between the rib spaces. Based on the excellent repeatability and reproducibility for renal length and width, it is recommended to use these measurements in rib spaces where parameters were maximal.