Canine Cryptorchidism : From Pathophysiology to Practical Management in Veterinary Practice

Cryptorchidism is more than just a developmental anomaly, it is a condition with significant reproductive, behavioral, and oncological implications. Understanding its pathogenesis, diagnosis, and management is essential for veterinarians aiming to deliver comprehensive reproductive care. 

What is Cryptorchidism? 

Cryptorchidism refers to the failure of one or both testes to descend into the scrotum within the first few weeks of life. In dogs, testicular descent typically completes by 35–40 days after birth . When this process is disrupted, testes may remain in the abdomen, inguinal canal, or ectopic sites such as subcutaneous tissues^1,2. 

The condition arises due to abnormalities in gubernacular development or persistence of suspensory ligaments, preventing normal migration¹. 

Epidemiology and Genetic Considerations 

Cryptorchidism affects approximately 10% of adult canines, with unilateral cases being far more common than bilateral ones. The right testicle is more frequently retained¹. 

Small breeds such as Yorkshire Terriers, Pomeranians, and Poodles show a higher predisposition, with a 2.7-fold increased risk compared to larger breeds¹. The condition is believed to follow an autosomal recessive inheritance pattern, further exacerbated by inbreeding practices¹. 

Clinical Presentation and Challenges 

Most cryptorchid dogs are asymptomatic, making incidental diagnosis common during routine examinations. However, retained testes continue to produce testosterone, leading to¹: 

• Aggression and territorial behavior 

• Hypersexuality 

• Foul-smelling urine 

In bilateral cases, sterility is common due to impaired spermatogenesis. Histological changes include germ cell degeneration, Sertoli cell abnormalities, and Leydig cell hyperplasia¹. 

Associated Disorders and Risks 

Cryptorchidism is linked with several complications: 

• Persistent Mullerian duct syndrome 

• Prostatic cysts 

• Feminization syndrome 

• Testicular tumors^1,3 

Neoplastic transformation is a major concern, with risks 9.2–13.6 times higher than normal testes. Tumor types include¹: 

• Seminomas (32–48%) 

• Leydig cell tumors (27–42%) 

• Sertoli cell tumors (20–40%)  

Sertoli cell tumors may metastasize to organs such as liver, spleen, and lungs in about 10% of cases⁴. 

Diagnostic Approach in Practice 

Clinical Examination 

Absence of testes in the scrotum remains the most definitive clinical sign. However, palpation alone is unreliable, with only 48% success in locating retained testes¹. 

Imaging Modalities¹ 

• Radiography: Limited utility; may show soft-tissue masses 

• Ultrasonography: Highly sensitive and preferred modality 

• CT Scan: Recommended when ultrasound findings are inconclusive 

Ultrasound helps differentiate testes from surrounding tissues based on echogenicity and structural features^1,5. 

Treatment Strategies: What Works Best? 

Hormonal Therapy 

Although GnRH may induce testicular migration, results are inconsistent¹. Moreover: 

• Androgen therapy is discouraged due to adverse effects 

• Hormonal treatment may allow genetic transmission of the defect^1,6 

Thus, its clinical use remains limited and cautious. 

Surgical Management 

Castration (orchiectomy) is the treatment of choice. Timing is crucial; surgery is recommended after six months to allow for possible delayed descent¹. 

Surgical approaches include: 

• Inguinal approach for palpable testes 

• Midline laparotomy for abdominal testes 

• Laparoscopy, increasingly preferred for minimal invasiveness¹ 

Vasectomy is rarely indicated and does not prevent hormonal complications^1,6. 

Complications and Prognosis 

Untreated cryptorchidism can lead to¹: 

• Testicular torsion, especially in abdominal testes 

• Hormonal imbalances 

• Behavioral abnormalities 

• Neoplasia 

Post-surgical complications may include infection, edema, and hemorrhage, but are generally manageable¹. 

Importantly, feminization syndrome caused by Sertoli cell tumors is often reversible after tumor removal, provided metastasis has not occurred¹. 

Preventive and Clinical Recommendations 

• Avoid breeding cryptorchid animals due to hereditary risk 

• Encourage routine examination in young dogs 

• Use ultrasonography early in non-palpable cases 

• Opt for surgical removal rather than hormonal correction 

Conclusion 

Cryptorchidism is a multifactorial condition requiring a proactive clinical approach. While often silent in presentation, its long-term consequences can be severe. Early diagnosis, appropriate imaging, and timely surgical intervention are key to preventing complications. For veterinarians, combining genetic awareness with clinical vigilance can significantly reduce the burden of this condition in canine populations. 

Reference 

1. Shrestha A, Neupane N, Nepal G, Rimal S. Bilateral Abdominal Cryptorchidism: A Case Study in Dog and Review of Its Relevant Consequences. Mathews Journal of Veterinary Science. 2025 May 30;9(5):1-8. https://www.mathewsopenaccess.com/full-text/bilateral-abdominal-cryptorchidism-a-case-study-in-dog-and-review-of-its-relevant-consequences 

2. Saren AK, Mandal D, Sarkar P, Chakraborty D, Das S, Baidya S. (2024). Surgical management of bilateral cryptorchidism with congenital agenesis of scrotum in a mongrel breed dog: A rare case report. Int J Vet Sci Anim Husbandry. 9(5):98-100. : https://doi.org/10.22271/veterinary.2024.v9.i5b.1658 

3. Park EJ, Lee SH, Jo YK, Hahn SE, Go DM, Lee SH, Lee BC, Jang G. Coincidence of Persistent Müllerian duct syndrome and testicular tumors in dogs. BMC veterinary research. 2017 Jun 2;13(1):156. https://link.springer.com/content/pdf/10.1186/s12917-017-1068-6.pdf 

4. Madureira R, Filho NDPR, Dos Santos AR, Dias AL, Headley SA, Mascarenhas NMF, et al. (2017). Seminoma and sertolioma in a male pseudohermaphrodite dog with unilateral cryptorchidism. Semina: Cienc Agrar. 38(4):2831-2836. https://www.redalyc.org/pdf/4457/445752611046.pdf 

5. Waqas MS, Arroyo E, Tibary A. (2024). Diagnostic Approach to Equine Testicular Disorders. Vet Sci. 11(6):243. https://www.mdpi.com/2306-7381/11/6/243 

6. Sun T, Xu W, Xu H, Chen Y, Niu Y, Wang D, et al. (2023). Hormonal therapy is effective and safe for cryptorchidism caused by idiopathic hypogonadotropic hypogonadism in adult males. Front Endocrinol. 13:1095950. https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2022.1095950/pdf