Inguinal herniation of the large colon in a cob gelding four weeks after castration.

This study describes a rare case of large intestinal herniation in a young cob gelding horse, which occurred four weeks after castration. The effected horse, initially treated for symptoms of colic, was discovered to have a segment of the large colon protruding through the inguinal canal, a complication not previously reported in horses.

Case Description

• A year-old cob gelding horse was brought to the Royal Veterinary College’s Equine Referral Hospital. The horse’s symptoms, which included visible distress and an attempt to lie down, and a firm swelling in the left inguinal region, were indicative of having colic. The horse had a history of undergoing castration four weeks prior to being admitted.
• Despite being administered various drugs to help alleviate pain, the horse’s condition did not improve. Subsequent rectal palpation, serum biochemistry, and abdominocentesis highlighted a large, inflated, and tympanitic organ extending from the cranial midline caudoventrally. The detection of a hyperechoeic bright line signifying gas in the scrotal swelling through percutaneous ultrasound supported suspicion of a hernia.
• Although surgery was proposed to fix the hernia, the owners rejected this option. All attempts to manually reduce the hernia proved unsuccessful, and final identification of the intestinal nature of the hernia was confirmed when percutaneous aspiration of the swelling yielded green fluid that contained plant material, extracellular, and intracytoplasmic cocci and bacilli. The horse was euthanized due to welfare concerns.

Postmortem Findings

• Postmortem examination of the horse revealed that 10 cm of the large colon’s pelvic flexure had endeavored through an enlarged left inguinal canal. Though the serosa of the herniated segment was observed to be slightly hyperaemic, no imminent harm was seen on the inguinal canal, leading to the assumption that the enlarged internal inguinal ring was likely born out of a pre-existing, probably congenital, condition rather than an abrupt development.
• The horse’s large colon displayed early ischaemic change. The report hypothesizes that the left testicle and scrotal fat, removed during castration, might have been preventing the herniation. A sudden rise in abdominal pressure following the operation might have contributed to the herniation, which ultimately presented as symptoms of acute colic.

Surgical Measures and Implications

• The authors discuss the debate amongst veterinary professionals regarding the significance of the size of the external and internal inguinal ring during castration procedures, especially in horses with pre-existing inguinal hernias. While some recommend suturing the external inguinal ring and closing the vaginal tunic, others argue about the necessity of these steps.
• This case underlines the critical role of the internal inguinal ring size, marked by a rare instance of large intestinal herniation, hence, altering the understanding and handling of such surgical procedures in the future.