Use of transabdominal ultrasonography to determine the location of cryptorchid testes in the horse

Abstract

Transrectal ultrasonography is a reliable technique to identify intra-abdominal testes, but can be hazardous or impractical in fractious, juvenile or small equids. The transabdominal approach therefore requires validation. To evaluate the sensitivity and specificity of transabdominal ultrasonography to localise cryptorchid testes. Thirty-eight horses admitted for cryptorchidism underwent transabdominal ultrasonography to locate errant testes. Location of the testes was confirmed during surgery (n = 37) or necropsy (n = 1). Horses weighed 175-760 kg. Twenty-two testes were located within the abdomen, 19 in the inguinal space and 3 in a subcutaneous location. In 2 horses, a thick winter coat prevented adequate contact between the probe and the skin, and visualisation of their inguinal testis and one abdominal testis was missed during transabdominal ultrasonography. Excluding the 2 horses with excessive hair, the sensitivity of transabdominal ultrasonography to locate errant testes was 97.6% (93.2% when all horses were included), and its specificity 100%. Transabdominal ultrasonography is a reliable, safe and immediate technique to diagnose cryptorchidism precisely in horses of all ages, sizes and temperaments. Transabdominal ultrasonography provides an immediate definitive diagnosis of adominal cryptorchidism and should enhance selection of an appropriate surgical approach for their removal.