SYMPTOM
Missing testicle in scrotum
Owners may observe missing testicle in scrotum in their pet.
Various conditions
This symptom can occur in multiple conditions and warrants further assessment.
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 tends to run in family lines.
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, in cold weather, or when a dog is anxious during handling. In this situation the testicle is present but temporarily out of reach on examination rather than genuinely retained, and it usually settles back into the scrotum once the dog relaxes or warms up.
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, and it is uncommon.
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 inguinal region, alongside a calm, non-painful presentation, points towards a surgical rather than developmental explanation.
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 a painful, sudden-onset problem, typically causing vomiting, abdominal pain and lethargy rather than a quiet change in what can be felt on examination, so it needs same-day veterinary attention. Long-standing atrophy of a retained testicle is a gentler, more gradual process that can shrink the gland until it is no longer distinguishable from surrounding tissue. Either way, this tends to reflect a change in a previously identified retained testicle rather than a lifelong absence.
Why timing matters
Early observation
Early recognition allows prompt assessment and intervention if needed.
Later presentation
Persistent or worsening signs may indicate progression requiring attention.
The significance of this symptom depends on its context, duration, and associated findings.
Conditions commonly associated
Cryptorchidism
One or both testicles absent from the scrotum is the defining feature of cryptorchidism.
Cushings Disease in Dogs
Cushing's disease can cause one or both testicles to atrophy and become smaller or less palpable within the scrotum due to the chronic excess of cortisol affecting testicular tissue. In some cases, the affected testicle may shrink enough that owners perceive it as missing when comparing sides or recalling previous examinations.
Lymphoma in Dogs
Lymphoma affecting the testicles or surrounding lymphoid tissue can cause asymmetrical swelling, distortion, or displacement that may lead owners to perceive one testicle as absent or altered in position. Testicular lymphoma, though less common than other forms, can also result in tissue changes that alter the normal scrotal anatomy.
Testicular Tumours
A testicle that has not descended into the scrotum carries a substantially higher risk of developing a tumour than one sitting normally.
Sertoli Cell Tumour
A testicle that never descended into the scrotum carries a substantially higher risk of developing this type of tumour than a normally positioned one.
When to explore further
When the symptom is persistent or worsening
When other signs are present alongside
When daily activities or quality of life are affected
When there is uncertainty about the cause
Noting when this symptom occurs, any triggers, and how it changes over time can provide useful information for veterinary discussions.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS