The testes perform two major functions in the male feline; the secretion of steroidal hormones and sperm production. When the testes are smaller than average, the production of both testosterone hormone and sperm is greatly decreased. A lack of circulated steroidal hormone influences secondary sex characteristics and the male phenotype. A small testicle means that there is less storage capacity for sperm and results in a low sperm production, or sterilization.

Small sized testes in cats is considered a disorder of sexual development that can be either an acquired or congenital condition. Testes lacking in diameter can affect cat of all ages and breed, but older or purebred felines are the common group affected by the condition. Small sized testes do not usually compromise a feline’s sexual behavior, but almost all felines with this condition have low sperm counts or are sterile, prohibiting reproductive abilities. Most cat owners will view feline sterilization as a positive outcome, as many do not require a producing feline. However, small sized testes can be a disorder related to disease and testicular degeneration that could become problematic in the near future. With that being said, if a cat owner believes their household cat possesses small sized testes, it is important to have the feline evaluated by a veterinary professional. 

Although your feline’s testicles are small in proportions, most felines still exhibit normal sexual behavior. The symptoms of small sized testes in cats can be a simple observation made by your veterinarian, or a variety of conditions you may notice at home. The clinical signs a feline may display with small sized testes varies with the condition at hand, but common symptoms of this ailment include: 

Immune-mediated orchitis is the condition in which sperm escapes the testes and causes the body to create anti-sperm antibodies. Trauma or a biopsy commonly causes the sperm to be released into the bloodstream, where the body recognizes the sperm as foreign invaders to be destroyed by the immune system.  

Testicular degeneration is a condition in which the testicular tissues breakdown resulting in soft, flabby and small testicles in a spacious scrotum. Testicular degeneration is commonly caused by illness and disease that have a common symptom of high fever. 

Testicular hypoplasia is the condition in which one or both testes are 25% smaller than the average testicle size of a feline. Testicular hypoplasia is a congenital disorder during sexual maturity. 

The most common cause of small sized testes in a cat is testicular degeneration and atrophy, but a variety of other conditions can also cause a feline to have underdeveloped male reproductive organs including: 

Small sized testes in cats can be diagnosed during a routine physical exam conducted by the veterinarian. Palpation of the scrotum will reveal the formation and dissention of the testes, which will clue the veterinarian in as to what might be the cause for the irregularly proportioned male organs. The doctor may analyze the feline’s fertility by running a sperm count. The sperm count is a relatively simple exam, as the amount of ejaculated sperm the cat produces is viewed under a microscope. The veterinarian will count the number of sperm in a field of view to estimate the total volume. The motility and physical nature of the sperm will also be evaluated during a sperm count exam. Additionally, the doctor may request an analysis of the feline’s steroidal hormones. If the hormone production is low, the likeliness of small testes and a possible underlying condition will be taken into consideration. 

The treatment of choice for small sized testes in cats is usually castration. The surgical removal of the feline’s underdeveloped sexual organs will remove the problem at hand and prevent future testicular complication from occurring. If the presence of an underlying illness or disease has been found, the veterinarian will also prescribe therapeutic treatment to aid the feline’s condition.

Recovery time for a cat that has undergone castration is very short and only takes a few days for the cat to return to normal. Once the testes have been removed, there is no need for the owner to manage the condition unless the problem involves accompanying sexual organs. In the case of additional complications or underlying disease, your veterinarian may advise follow-up care.