Transrectal ultrasonography of the left adrenal gland in healthy horses.

The researchers have examined the use of transrectal ultrasonography to study the appearance of the left adrenal gland in healthy horses, and found it to be a feasible method for further exploration of equine adrenal gland health and physiology.

Key Findings

• The study’s main objective was to investigate the potential of using transrectal ultrasonography to characterize the normal adrenal gland in horses. This was driven by the lack of existing information in this area of veterinary medicine.
• The researchers conducted this study on 25 healthy horses using a 7.5 MHz linear array probe at a displayed depth of 8 cm. They found that the same method could not be applied to study the right adrenal gland.
• For investigating the left adrenal gland, the horses’ left kidney, the abdominal aorta, the left renal artery, the left renal vein, and the cranial mesenteric artery were used as landmarks. This allowed the researchers to delineate and study the adrenal gland in detail.

Nature and Appearance of the Adrenal Gland

• The size of the left adrenal gland was found to be variable among the horses. In most cases, it appeared as a long, flat structure, featuring a hyperechoic (highly reflective of ultrasound waves) medulla enclosed by a hypoechoic (less reflective) cortex.
• In 44% of the horses (11 out of 25), the researchers were unable to properly delineate the most cranial part of the gland.

Measurements and Visualization

• Measurements of the thickness of the gland and the medulla were taken near the caudal (near the tail) pole, cranial (near the head) pole, and in the middle of the gland. Similarly, the length of the entire adrenal gland and of the medulla was also recorded.
• The results indicated that transrectal ultrasonography provides sufficient visualization of the left adrenal gland in horses, offering promise for further diagnostic and research use in the study of equine adrenal gland health and physiology.