Small Sized Testes in Dogs

By PetMD Editorial on Oct. 5, 2010

Testicular Degeneration and Hypoplasia in Dogs

Smaller than normal testes are generally easy to spot. There are different conditions that can lead to this disorder: underdevelopment or incomplete development of the testes is known as hypoplasia, an inability to grow and/or mature appropriately; and degeneration of the testes, which refers to the loss of potency after the stage of puberty has arrived.

Both of these conditions can be due to a condition that was present at birth -- congenital -- or can be due to some other cause that takes place after birth. The congenital forms are usually related to genetic abnormalities that have been inherited by the parent, but may also be due to something that occurred while the puppy was in utero, such as exposure to radioactive substances.

Dogs of any age or breed are predisposed to these conditions, but hypoplasia is most commonly seen in young dogs, and degeneration is more common in older dogs.

Symptoms and Types

In addition to abnormally small testes, infertility is the single most common symptom of these conditions. Semen analysis will show a low sperm count (oligospermia) or an absolute absence of sperms (azoospermia) in the seminal fluid is usually reported.


  • Degeneration of the testicular sacs
  • Radiation exposure
  • Metal toxicity, including lead
  • Chemical toxicity
  • Other toxins
  • Exposure to heat
  • Inflammation of the testes (orchitis)
  • Hormone imbalance
  • Increasing age
  • Adverse drug reaction (e.g., antifungal drugs)
  • Hypoplasia
  • Genetic
  • Injury, trauma
  • Tumor of the pituitary gland


Dogs with these conditions are typically presented to their veterinarians with a compliant of infertility. You will need to give a complete known history, including any such problems that were present in the previous generations of your dog's familial line and any trauma or injury that may have affected your dog's scrotum.

Your veterinarian will thoroughly examine the scrotal region and should be able to immediately ascertain whether they are of normal size or are smaller than what they should be for your dog's breed, size and age. A finding of abnormal size is enough to urge your veterinarian to conduct further tests in order to differentiate testicular degeneration from hypoplasia. An ultrasound image of the testes is usually done to confirm the visual diagnosis of smaller than normal testes.

Your veterinarian will also take a semen sample for laboratory testing, to check for abnormal cell development and to do a standard sperm count. The sperm count will evaluate the number of viable sperm cells in your dog's semen. If it appears to be called for, under the circumstances, a small tissue sample may also be taken from the testicular sac, using a fine needle, to be sent to the laboratory for further evaluation.


Treatment depends on diagnosis of the underlying cause of degeneration or hypoplasia. Hormonal therapy has been used in animals with these conditions with variable results reported. Your veterinarian will discuss the possibilities of your dog's future fertility using the various treatment protocols that are available, depending on the final diagnosis. Treatment is not available in all cases, but this cannot always be determined without the appropriate tests being conducted first.

If your doctor does determine that treatment is a viable option, follow-up visits will include serial semen analyses to evaluate the efficacy of the therapy.

Living and Management

There is no special at home care that is recommended for dogs with testicular hypoplasia or degeneration. You may need to take your dog for subsequent laboratory testing during the period of treatment, but this will be entirely dependent on the diagnosis your veterinarian has settled on and the treatment protocol that has been outlined for him.

Dogs with hypoplasia have a poor chance of ever becoming fertile; the chances are a bit better for dogs with degeneration of the testes, but in general, the prognosis for successful breeding remains poor. In any case, the prognosis depends on the underlying cause and successful response to treatment.

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