Inguinal Hernia in Horses

Q:My 8-year-old gelding has been diagnosed with a hernia between the omentum (a fold of the abdominal tissue surrounding the organs) and the inguinal ring (an opening deep within the groin area through which the spermatic cord passes).

I first noticed a large, hard lump (about the size of my palm) just below his stomach, on the upper part of his sheath or scrotum along with huge swelling of the sheath area which I initially thought was a hygiene issue. He has had no signs of real discomfort, his bowel movements have been the same, and he doesn't have any problems with urination.

I have had two different vets look at it, test his blood for any abnormalities, and on the vet's last visit he conducted both external and rectal ultrasound exams.

All bloodwork came back normal, the external ultrasound showed multiple pockets of liquid in this hard lump, and the veterinarian was unable to find the inguinal ring on rectal ultrasound. After conferring with a surgeon the vet diagnosed it as a hernia.

Of course, the surgeon said he will do another ultrasound prior to surgery since he is not the one who has actually seen my horse.

My question is, simply, are there more possibilities of what this could be, do I have enough information to schedule the surgery, and/or what more should I know/learn prior to scheduling a hernia removal surgery?

Rahna Fafnis, via e-mail

A:Sudden development of a hernia in the region adjacent to the sheath would be very unusual, unless it was associated with a surgical procedure or major trauma (such as collision with a fence). It's important to remember exactly what a hernia is--a defect in the body wall so that there is communication between the abdominal cavity (where the intestines are) and the tissue beneath the skin. The inguinal canal is a natural opening in the body wall that is sometimes large enough to allow abdominal organs (intestines or omentum) to get through to the scrotum or tissue around the sheath, creating an inguinal hernia. In your horse's case, the rule outs for a hard lump such as you describe would include an abscess, a tumor, or a hernia. The area you describe is likely difficult to examine and image, particularly given the swelling that has occurred.

However, a hernia in that area might be in a position where it can be felt during rectal palpation and seen on ultrasound using an imaging probe that can penetrate the full depth of the mass down to the body wall. If a break in the body wall cannot be documented, then the veterinarian could aspirate one of the fluid pockets to assess for the possibility of infection. Surgery might well be required to remove the mass or to open the mass to drain. If the surgeon detects a hernia, he or she would need to approach the case with abdominal wall closure rather than mass removal. The surgeon will be able to tell you a lot more about your options once the lump has been further examined, but you are right in questioning what else the lump could be.

The veterinarians you have worked with have given you a lot of useful information and some excellent advice. I would agree that you should give strong consideration to taking your horse to a specialty hospital with a surgery staff. A surgeon will do a thorough workup and give you a lot more information so that you can make an informed decision. Surgery might be an option, but not before a final diagnosis has been made.

About the Author

Anthony Blikslager, DVM, PhD, Dipl. ACVS

Anthony Blikslager, DVM, PhD, Dipl. ACVS, is a professor of equine surgery and gastroenterology at North Carolina State University’s College of Veterinary Medicine. His research interest is gastrointestinal physiology in horses, studying the mechanisms of injury and repair in the gut with the clinical outlook of enhancing recovery of horses with colic.

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