Retained Testicle in Dogs (Cryptorchidism)
- Occurrence: common
- Location of disease: Abdomen/pelvis
When to visit the vet?
Non-urgent see a veterinarian within 2–3 days
If the condition worsens / symptoms persist, consult a veterinarian.
Definition
Cryptorchidism is a developmental disorder in male dogs where one or both testicles fail to descend into the scrotum. Instead, they remain in the abdominal cavity or the inguinal canal.
The most important facts at a glance
Cryptorchidism, also known as retained testicle, affects about 1–3% of male dog puppies. Normally, the testicles descend into the scrotum by the eighth week of life, but in cryptorchidism this process remains incomplete. Genetic factors play a key role, especially in breeds such as German Shepherds, Boxers, and Chihuahuas, indicating a hereditary predisposition. Hormonal and environmental influences during pregnancy can also affect testicular descent. Symptoms are usually a missing testicle in the scrotum or swelling in the groin area, which can cause infertility. Diagnosis is made through a physical examination, occasionally supported by ultrasound. The main treatment is surgical removal of the undescended testicle to reduce the risk of testicular tumors. In cases of unilateral cryptorchidism, the healthy testicle is often also removed to prevent genetic transmission. The prognosis is good if treated early. For prevention, affected dogs should not be used for breeding. Research focuses on genetic causes and environmental influences to develop better diagnostic and treatment methods.
Causes
Undescended testes is a relatively common anomaly in dogs and occurs in about 1–3% of male puppies. The normal descent of the testicles into the scrotum occurs in the first weeks of a puppy’s life, typically by the eighth week. In cases of cryptorchidism, this process remains incomplete.
The causes of cryptorchidism are not fully understood, but it is believed that genetic factors play a key role. The condition occurs more frequently in certain breeds, including German Shepherds, Boxers, Chihuahuas, and Poodles. This suggests that hereditary factors contribute significantly to the predisposition.
In addition to genetic factors, hormonal and environmental influences during the mother’s pregnancy could also play a role. For example, disruptions in testosterone levels could affect the normal development and descent of the testicles.
Symptoms
The most noticeable symptom of cryptorchidism is the absence of one or both testicles in the scrotum, which is identified during a physical examination. If the examination is incomplete, the condition may go unnoticed.
Another symptom can be an asymmetrical or irregular size of the scrotum if only one testicle is affected. In bilateral cryptorchidism, the testicles are completely hidden in the abdominal cavity, making them difficult to detect.
Affected dogs may have an increased risk of testicular tumors in adulthood, especially if the testicles remain in the abdomen. Furthermore, cryptorchidism can lead to behavioral problems such as aggression, which are influenced by elevated testosterone levels.
Therapy
The recommended treatment for cryptorchidism is the surgical removal of the undescended testicle, a procedure known as cryptorchidectomy. This significantly reduces the risk of testicular tumors and other health complications.
In cases of unilateral cryptorchidism, the descended testicle is often also removed to minimize the risk of passing on the anomaly genetically. Castration / neutering also prevents unwanted behavioral problems associated with elevated testosterone levels.
In some cases, especially in valuable breeding animals, hormonal treatment may be considered to promote testicular descent. However, this method is controversial and not always successful.
Prognosis and follow-up care
The prognosis for dogs with cryptorchidism is generally good, especially if the condition is detected and treated early. Surgical removal of the affected testicle is a routine procedure with low risk and a short recovery time.
If left untreated, there is an increased risk of developing testicular tumors, which can worsen the prognosis. Testicular tumors in cases of cryptorchidism are often more aggressive and harder to treat, which is why early removal of the affected tissue is important.
After treatment, most dogs can lead a normal, healthy life. Neutering can also help reduce behavioral problems that may accompany the condition.
Prevention
Since cryptorchidism has a genetic component, the best prevention is not to use affected dogs for breeding. This prevents the passing on of the genetic predisposition to future generations.
Regular veterinary examinations in the first months of a puppy’s life are important to detect cryptorchidism early. This allows for timely treatment and prevents possible complications.
A healthy diet and proper care of the pregnant bitch can also help minimize the risk of developmental disorders in the offspring, although this alone cannot fully prevent cryptorchidism.
Outlook on current research
Cryptorchidism, also known as retained testicle, is one of the most common congenital disorders of the reproductive organs in dogs. This condition has attracted considerable attention in the scientific community because it can not only impair the fertility of affected animals, but also increase their risk of certain health problems, such as testicular cancer and testicular torsion. Current research focuses on various aspects of this condition, including genetic predispositions, environmental influences, and improved diagnostic and therapeutic approaches.
A major focus of research is identifying genetic markers responsible for cryptorchidism. Scientists have found that it is a polygenic condition, meaning that multiple genes are involved in its development. Modern techniques such as genome sequencing and association studies are used to identify specific gene variants linked to an increased risk of cryptorchidism. These discoveries could lead to genetic tests in the future, enabling breeders to better assess the risk of cryptorchidism in their breeding lines.
Another area of research examines the role of environmental influences in the development of cryptorchidism. Studies have shown that certain chemical substances known as endocrine disruptors can disrupt hormonal balance during embryonic development, which can lead to an increased risk of cryptorchidism. These substances can be found in pesticides, plastic products, and other industrial chemicals. Research aims to better understand these compounds and develop strategies to minimize exposure during critical developmental phases.
With regard to the treatment of cryptorchidism, current studies focus on developing less invasive and more effective surgical techniques. While castration / neutering of the affected dog is the most common treatment method, some researchers are exploring the possibility of relocating the testicles back to their original position to preserve fertility. However, these surgical techniques are still in the experimental phase and require further investigation to assess their safety and effectiveness.
In summary, research into cryptorchidism in dogs is making promising progress. The combination of genetic studies and the investigation of environmental influences could lead to better prevention and treatment of this condition in the future. This would not only benefit the health of affected dogs, but could also improve breeding practices and expand the overall understanding of reproductive biology in mammals.
Frequently Asked Questions (FAQs)
1. What is cryptorchidism in dogs?
2. How common is cryptorchidism in dogs?
3. What causes cryptorchidism?
4. What risks are associated with cryptorchidism?
5. How is cryptorchidism diagnosed?
6. What are the treatment options for cryptorchidism?
7. Can dogs with cryptorchidism be bred?
8. Are there ways to prevent cryptorchidism?
9. At what age should a dog with cryptorchidism be castrated / neutered?
10. Does cryptorchidism affect a dog's behavior?
Literature
- Cho, S. E., Fudge, J. M., Page, B., Kim, S., & Yu, D. (2025). Cryptorchidism in dogs and cats presented for elective gonadectomy: A descriptive cohort study of 306 animals treated between 2018 and 2023. Topics in Companion Animal Medicine, 65, Article 100961. https://doi.org/10.1016/j.tcam.2025.100961
- Soto-Heras, S., Reinacher, L., Wang, B., Oh, J. E., Bunnell, M., Park, C. J., Hess, R. A., & Ko, C. J. (2024). Cryptorchidism and testicular cancer in the dog: Unresolved questions and challenges in translating insights from human studies. Biology of Reproduction, 111(2), 269–291. https://doi.org/10.1093/biolre/ioae075
- Stachowiak, M., Nowacka-Woszuk, J., Szabelska-Beresewicz, A., Zyprych-Walczak, J., Krzeminska, P., Sosinski, O., Nowak, T., & Switonski, M. (2024). A massive alteration of gene expression in undescended testicles of dogs and the association of KAT6A variants with cryptorchidism. Proceedings of the National Academy of Sciences of the United States of America, 121, Article e2312724121. https://doi.org/10.1073/pnas.2312724121
- Hernández-Jardón, N., Rojas-Castañeda, J. C., Landero-Huerta, D., Reyes-Cruz, E., Reynoso-Robles, R., Juárez-Mosqueda, M. L., Medrano, A., Reyes-Delgado, F., & Vigueras-Villaseñor, R. M. (2022). Cryptorchidism: The dog as a study model. Frontiers in Veterinary Science, 9, Article 935307. https://doi.org/10.3389/fvets.2022.935307
- Blades, M., Freyer, J., Donner, J., Chodroff Foran, R., & Forman, O. P. (2022). Large scale across-breed genome-wide association study reveals a variant in HMGA2 associated with inguinal cryptorchidism risk in dogs. PLOS ONE, 17(5), Article e0267604. https://doi.org/10.1371/journal.pone.0267604
- Pecile, A., Groppetti, D., Pizzi, G., Banco, B., Bronzo, V., Giudice, C., & Grieco, V. (2021). Immunohistochemical insights into a hidden pathology: Canine cryptorchidism. Theriogenology, 176, 43–53. https://doi.org/10.1016/j.theriogenology.2021.09.011
- Khan, F. A., Gartley, C. J., & Khanam, A. (2018). Canine cryptorchidism: An update. Reproduction in Domestic Animals, 53(6), 1263–1270. https://doi.org/10.1111/rda.13231