Cryptorchidism is considered an inherited tendency.
In ruminants, cryptorchidism is supposedly generally due to an ectopic testicle eg a testicle found someplace outside of the abdominal cavity due to abnormal gonadal cell development. See pgs 260-261 in Surgery of the Scrotum, VCNA 2008. However, more reports are finding the testicles abdominally.
Cryptorchid testicles are commonly found abdominally in swine. Pigs can also have ectopic testicular tissue. To remove the cryptorchid testicle in pigs, an incision in made in the paralumbar fossa with the pig in lateral recumbency with the affected side up. The testicle is usually large and will be on a path between the kidney and the inguinal ring (the descent path).
ABSTRACT
This paper describes features of a study of different aspects of cryptorchidism in sheep in different parts of England. A total of 83 crytorchid testes (57 unilateral and 13 bilateral) were recognised in 70 animals post-slaughter at three abattoirs in the south west of England between June 2000-January 2004. Abdominal cryptorchids (60) were common than inguinal (23); 69% percent of cases were unilateral. External examination for cryptorchidism was carried out on 5134 young male lambs carried out in 2001 at Foot and Mouth Disease disposal sites, and on farms, during the UK outbreak of the disease. A total of 29 cases of cryptorchism [0.56%] were detected; 86% of cases were unilateral. In both situations the right testis was more commonly affected than the left.
(10) (PDF) Cryptorchidism in Sheep: A Clinical and Abattoir Survey in the United Kingdom. Available from: https://www.researchgate.net/publication/276491292_Cryptorchidism_in_Sheep_A_Clinical_and_Abattoir_Survey_in_the_United_Kingdom [accessed Jul 15 2019].e.
Location of undescended testes differs greatly among species. For cats, dogs and horses, 50, 92 and 47-60% of retained testes were in the abdominal cavity, although 1 report for horses gave 33% abdominal (see Table 1 in Amann and Veeramachaneni, 2007). There are no reliable data for pigs, but subcutaneous locations might predominate. From
Cryptorchidism and associated problems in animals R. P. Amann and D. N. R. Veeramachaneni A, Anim Reprod 20
Resources
JM Ewoldt. Surgery of the scrotum, Vet Clin Food Anim 24 (2008):253–266
Scolo et al. Pig surgery: cryptorchidectomy using an inguinal approach. Vet Rec 2016
SS Nair. Ultrasound Diagnosis of Cryptorchidism in Sheep. Frontier J. Vet. Anim. Sci.Vol.4, No.1(Jan-June) 2015
R P Amann and D N R Veeramachaneni. Cryptorchidism in common eutherian mammals. Reproduction 133(3), 2007- very thorough coverage!
Testicular descent animation
