When Testicles Do Not Descend: More Than a Cosmetic Issue
In a healthy male puppy, both testicles should be present in the scrotum by the time the dog is two months old. When one or both testicles fail to descend into their normal position, the condition is called cryptorchidism. It affects roughly 1.2 to 10 per cent of male dogs depending on breed, and while it may appear to be a minor anatomical quirk, the health consequences are anything but minor. A retained testicle carries a significantly elevated risk of becoming cancerous — up to thirteen times higher than a normally descended testicle.
Understanding Why It Happens
During foetal development, the testicles form near the kidneys and migrate downward through the inguinal canal into the scrotum. In cryptorchid dogs, this migration stalls at some point along the route. The retained testicle may sit within the abdomen, within the inguinal canal, or just beneath the skin near the groin.
Cryptorchidism has a strong hereditary component. Several breeds show notably higher rates, including the Chihuahua, Dachshund, Boxer, Pomeranian, Maltese, Pekingese, and Shetland Sheepdog. Because it is inherited, affected dogs should not be used for breeding — and reputable breeders screen actively for this condition.
The Health Risks of Leaving It Untreated
Testicular Torsion
A retained testicle sits in an abnormal location with more room to move than a scrotal testicle. This mobility creates the risk of testicular torsion — where the testicle twists on its own blood supply. Torsion causes sudden, severe abdominal pain and is a genuine emergency. Dogs experiencing torsion will typically show acute distress, vomiting, and collapse. Immediate surgical intervention is required.
Testicular Neoplasia
The most serious long-term risk is cancer. The abdominal environment is warmer than the scrotum, and this elevated temperature disrupts normal testicular tissue development and function. Three tumour types are commonly associated with retained testicles: Sertoli cell tumours, seminomas, and interstitial cell tumours. Sertoli cell tumours are of particular concern because they can secrete oestrogen, leading to a syndrome of feminisation in affected dogs — including breast tissue development, a pendulous prepuce, and bone marrow suppression.
Infertility
While a dog with one descended testicle may still produce sperm and be technically fertile, the retained testicle itself is typically non-functional in terms of sperm production due to heat exposure. Dogs with bilateral cryptorchidism — both testicles retained — are usually sterile.
Diagnosis
A veterinarian will palpate the scrotum and inguinal region during a routine examination. If a testicle cannot be located externally, ultrasound is the most effective tool for locating an abdominal testicle. In some cases, particularly with small abdominal testicles, this requires an experienced ultrasonographer.
Puppies are typically assessed at their first and second vaccine appointments, then re-evaluated at neutering age. If both testicles have not descended by six months, the likelihood of spontaneous descent is very low.
Treatment: Why Surgery Is Always Recommended
The appropriate treatment for cryptorchidism is surgical removal of the retained testicle, combined with castration of the descended testicle. There is no medical treatment that reliably causes a retained testicle to descend, and hormone injections sometimes advertised for this purpose are not considered ethical or effective by mainstream veterinary bodies.
Surgery is recommended regardless of whether the dog shows symptoms. The risk of malignant transformation increases with age, meaning that the longer a retained testicle remains in situ, the greater the likelihood of cancer developing — often silently until the disease is advanced.
The surgical approach varies depending on the testicle's location. An inguinal testicle can often be removed through a relatively small incision. An abdominal testicle requires laparoscopic or open abdominal surgery. Both are routine procedures in experienced hands, and recovery is typically straightforward.
What Owners Should Watch For
If you have a male dog whose cryptorchidism has not yet been addressed, be alert to the following signs, which may indicate a Sertoli cell tumour or torsion:
- Symmetrical hair loss, particularly along the flanks and perineum
- Development of breast tissue or a swollen prepuce
- Attraction from other male dogs
- Abdominal swelling or a palpable mass
- Sudden abdominal pain, vomiting, or collapse
- Lethargy, pale gums, or signs of anaemia
These signs warrant urgent veterinary assessment. Sertoli cell tumour-associated anaemia, caused by oestrogen suppressing the bone marrow, can be life-threatening and requires prompt treatment beyond surgery alone.
A Practical Summary for Dog Owners
- Ask your vet to confirm both testicles are present at your puppy's vaccination appointments
- If cryptorchidism is identified, schedule surgical consultation — ideally before your dog reaches twelve months
- Do not breed a cryptorchid dog, as the condition is heritable
- If surgery has been postponed, monitor your dog closely for the signs listed above and discuss the increasing cancer risk with your vet
- Understand that surgery is not optional in the long term — it is the only reliable way to eliminate the risk of torsion and malignancy
Cryptorchidism is one of those conditions where the right intervention is clear and the window for acting safely is wide — but that window does not stay open indefinitely. Early surgery protects your dog and removes the risk entirely.