What are the methods for determining unilateral cryptorchidism in pigs?

Cryptorchidism in pigs is divided into unilateral cryptorchidism and bilateral cryptorchidism. Unilateral cryptorchidism is common, while bilateral cryptorchidism is rare. How can you determine which side of the pig's abdominal cavity the unilateral cryptorchidism is on? Based on my many years of clinical practice, I have found that whichever side's ear of the pig is standing upright, the cryptorchidism is in the abdominal cavity on that same side.

Surgery for unilateral cryptorchidism is generally performed in two stages: first the testis on the outer side is removed, and after the incision heals, the cryptorchid testis on the opposite side is removed. During this period, if the piglet is sold or another operator takes over, and if the side of the abdominal cavity where the cryptorchid testis is located cannot be accurately determined, the surgery becomes very difficult.

The pig's body is a complete and unified whole, and each part is inseparable, with the nervous system playing the leading role. For example: after the left testis of the pig is removed, the excitability of the nerves governing that side's testis decreases, so the left ear droops at an angle, while the right ear stands upright. This special symptom proves that the cryptorchid testis is in the right abdominal cavity, so the surgery should be performed on the right side.