SYMPTOM
Missing testicle in scrotum
Owners usually notice that only one testicle, or neither, can be felt in the scrotum, or that the scrotum looks smaller or uneven on one side.
Developmental Non-Descent (Cryptorchidism)
During normal development each testicle migrates from near the kidney down through the inguinal canal into the scrotum, usually completing before eight to ten weeks of age. When this migration stalls, the testicle remains lodged in the abdomen or inguinal canal and is never palpable in the scrotal sac. Toy and small breeds, including Yorkshire Terriers, Toy Poodles, Pomeranians and Chihuahuas, are recognised as more likely to show this pattern, and it is inherited, so affected dogs are advised not to be used for breeding. Descent after about six months of age is rare, and a retained testicle carries a higher risk of tumours than a scrotal one.
Retractile Testis (Normal Variation)
A strong cremaster muscle reflex can pull an otherwise normally descended testicle up towards the inguinal canal, particularly in younger dogs or when a dog is stressed or frightened during handling. In this situation the testicle is present but temporarily out of reach on examination rather than genuinely retained, and it usually returns to the scrotum once the dog relaxes.
Testicular Absence (Monorchidism or Anorchism)
Occasionally a testicle fails to form at all, or is lost to an in-utero vascular event before birth, leaving genuinely only one, or rarely no, testicle rather than one that has simply failed to descend. This differs from cryptorchidism in that there is no retained gland anywhere in the abdomen to locate. It is considered rare in dogs, its frequency has not been studied, and it cannot be told apart from a retained testicle by feel: imaging, hormone blood tests or surgery are needed to confirm it.
Previous Neutering or Partial Castration
A testicle that was surgically removed, including during a prior cryptorchid castration where only the scrotal testicle was taken at the time, will understandably no longer be present. A small scar near the scrotum or in the groin points towards previous surgery, but it cannot confirm that all testicular tissue was removed. A blood test for anti-Müllerian hormone, which falls to very low or undetectable levels after castration, can show whether testicular tissue remains.
Testicular Torsion or Atrophy
A retained abdominal testicle is more prone to twisting on its own blood supply than a normally descended one. Torsion is painful and sudden in onset. In a published series of six cryptorchid dogs with a twisted abdominal testicle, five had abdominal pain and loss of appetite and three vomited; lethargy and shock can also occur. It needs veterinary assessment the same day, and treatment is surgical removal of the testicle, which was curative in five of the six dogs. Separately, a retained testicle often degenerates over time, and a small, degenerate testicle in the groin can be hard to feel. Both of these concern a testicle that is already retained, rather than explaining why it is absent from the scrotum.
Why timing matters
Early observation
Checking both testicles at puppy health checks allows a retained testicle to be identified before about six months of age, after which descent is rare.
Later presentation
A testicle still retained in an adult dog carries a higher risk of tumours and of twisting on its blood supply than a scrotal one, and removal of retained testicles is recommended.
The finding itself does not change from day to day. What matters is whether the testicle is retained, retractile, absent or already removed, which examination, and sometimes imaging or blood tests, can establish.
Conditions commonly associated
Cryptorchidism
One or both testicles absent from the scrotum is the defining feature of cryptorchidism.
Cushings Disease in Dogs
Testicular atrophy in entire males is listed as an uncommon sign of Cushing's disease. Atrophied testicles are smaller but still lie in the scrotum, so a testicle that cannot be felt at all points more towards retention or previous surgery.
Testicular Tumours
A testicle retained in the abdomen or groin is reported to carry 9 to 14 times the tumour risk of a scrotal testicle, with Sertoli cell tumours and seminomas the most common types.
Sertoli Cell Tumour
About half of Sertoli cell tumours in dogs (54% in one review) arise in retained testicles. These tumours can produce oestrogen, causing enlarged nipples, a pendulous prepuce and hair loss.
The page on this condition is being checked again and is offline for now.
When to explore further
When a testicle is still missing from the scrotum at around six months of age, after which descent is rare
When a dog with a known or suspected retained testicle develops sudden abdominal pain, vomiting, loss of appetite or lethargy, which can signal torsion and needs assessment the same day
When enlarged nipples, a pendulous prepuce or hair loss develop, which can reflect an oestrogen-producing tumour in a retained testicle
When it is unclear whether a dog that has had surgery still has testicular tissue
Noting whether the testicle can ever be felt in the scrotum, for example when the dog is relaxed, and gathering any records of previous surgery can provide useful information for veterinary discussions.
Last reviewed: 10 October 2026 · Dr Alastair Greenway MRCVS