The Mystery of the Missing Testicle in Some Dogs (and Cats)

This isn’t a magic trick. Sometimes testicles do not descend as expected in dogs and cats. Learn to identify dangers and look for symptoms.

Missing testicle in a dog
You want to check my WHAT?! Cryptorchidism affects male dogs and cats.

This isn’t the work of Houdini but a real issue for male dogs and cats. Males can be born missing one or both testicles, also known as cryptorchidism. A testicle could be retained in the abdomen, be completely undeveloped or be retained while another descends (known as monorchidism).

What Happens in Development

Normal male development occurs when the testicles descend from the abdomen into the scrotum. This usually occurs in the first two months of life but can be delayed up to six months. If descent is not seen by 6 months of age, consult your veterinarian.

Abnormal male development occurs when one or both testicles are retained in the abdomen or are undeveloped. The reasons for this condition are largely believed to be the result of a genetic trait, but other reasons are possible. This condition can appear in any breed but is thought to be more common in toy and miniature breeds of dogs.


Cats can also be affected too, so this is not a selective canine disorder. Males with this condition should not be bred for fear of passing on the condition genetically, and there is an increased risk of health problems and cancer. If the condition is found, it is advised to have the animal neutered to prevent further health complications.

For detailed images of visual identification of this disorder, view these images from Ron Hines, DVM, PhD.

How to Recognize Cryptorchidism

This condition can be hard to recognize in your pet. It’s not a condition usually known to be painful unless the retained testicles twist internally, and that will cause severe abdominal pain. For other cues, watch out for these symptoms:

  • Visual absence of one or both testicles
  • Differences in urinating behavior
  • Continued mating behavior (humping) after a neutering procedure
  • Aggression, especially toward intact males perceived to be competition for mates
  • Infection or tumors in the testicular area
  • Darkened skin in the testicular area
  • Impregnation of a female after being neutered

This video explains a description of the condition by a veterinarian and his patient:

What to Do Next

Your vet may notice this condition during an examination or vaccination appointment. If your male puppy (or kitten) reaches 6 months of age and you notice any of the symptoms listed above, talk to your vet about it. Your vet can use either laboratory tests or an ultrasound to evaluate the condition (or the absence thereof). Removal of both testicles is recommended when this condition is present. This may be done surgically, but in some cases the testicle may be able to massaged down into the scrotum for a less invasive procedure.

Please keep in mind that surgeries where the testicle cannot be descended may require a longer recovery period and a higher expense. It is in the best interest of your dog or cat to get this operation done to reduce future health issues and the possibility of cancer, so please do not ignore the symptoms or diagnosis by your vet. Recovery and future health rates are very positive for dogs and cats who have this condition properly treated.


This condition can be serious, and early detection is important. Please don’t delay; take care of this as soon as possible. You may be able to prevent subsequent health issues and reduce the likelihood of cancer in your pet. Check for the symptoms and notice if your pet is in pain. This could be the result of the testicles being twisted or entwined internally. Don’t ignore the warning signs, and get to your vet at the first suspected symptom. Your pet is depending on you.

Photo: darkuncle/Flickr


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