What is infertility?
Male infertility refers to the inability of a sexually mature tomcat (intact male cat) to impregnate a fertile female cat. Most tomcats reach sexual maturity between six and twelve months of age, although this can sometimes occur as late as 18 months old. A tomcat that has been unable to sire a litter with a proven fertile female by 18 months of age may be evaluated for infertility.
What causes infertility in male cats?
Some cases of male infertility may be genetic in nature. This is the case in male calico and tortoiseshell cats, because these cats carry the chromosomes XXY instead of the normal XY seen in males. Some cats may be born as pseudohermaphrodites, possessing both male and female sexual characteristics, while others have different inherited abnormalities of the reproductive system. Some Persian cats are reported to possess a low sex drive, though the reason for this is not fully understood.
Behavioral factors may also be associated with infertility in tomcats. An anxious tomcat, or one that has had negative experiences associated with breeding in the past, may be reluctant to mate with a female. Attempting to breed cats in a stressful environment may be associated with lower breeding success.
Less commonly, testicular diseases can contribute to infertility. The testicles may be retained within the abdomen (cryptorchidism), abnormally small (atrophied), or affected by tumors. Any of these testicular conditions may interfere with sperm production, decreasing fertility as a result.
Systemic infections may affect a tomcat’s testicles and fertility. These infections include tuberculosis, feline infectious peritonitis (FIP), feline leukemia virus (FeLV), and feline immunodeficiency virus (FIV). Prostate cancer and prostate infections are rare but possible and may require investigation.
Disorders of the penis may prevent successful mating. These disorders may be hereditary defects or caused by trauma. Commonly observed disorders of the penis in cats include priapism (persistent erection), paraphimosis (inability to retract the penis into the sheath), and phimosis (inability to extend the penis from the sheath).
In long-haired cats, the entanglement of long hair can lead to problems with the penis and successful breeding; improved grooming may resolve these breeding concerns. Back or pelvis pain may also inhibit the male cat from successfully mounting the female cat.
How will my veterinarian determine the cause of my cat's infertility?
Your veterinarian will begin with a thorough physical examination. Diagnostic testing may be recommended based upon physical exam findings and may include some or all of the following:
1. Complete blood cell count (CBC) and serum biochemistries. Screening blood work, including thyroid levels, can be used to assess your cat's overall internal health and reveal possible causes of infertility. A urinalysis may also be performed to assess for the presence of urinary tract disease.
2. Infectious disease testing. These tests assess for viral infections such as FeLV, FIV, and FIP.
3. Semen testing. If possible, your veterinarian will obtain a sample of your cat's semen for evaluation. Some tomcats can be trained to provide a sample for assessment, while others may require sample collection under anesthesia. Your veterinarian will examine the semen to ensure that the sperm are structurally normal, with normal motility (movement).
4. Testosterone testing. Circulating levels of testosterone can vary significantly in normal cats, depending on the time of day and other factors. Therefore, assessing testosterone levels requires more specialized testing, such as a gonadotropin releasing hormone (GnRH) response test or a human chorionic gonadotropin (hCG) response test. In these tests, a cat is injected with a hormone known to trigger testosterone release and testosterone levels are assessed one to two hours after the injection.
5. Abdominal imaging. X-rays and ultrasound may be used to evaluate internal structures, such as the testicles or prostate gland.
How is infertility in male cats treated?
The treatment of infertility and its prognosis with treatment depends on the underlying cause. In many cases, improving sanitation, alleviating overcrowding, and taking measures to reduce stress can improve fertility. Improved grooming may also facilitate breeding in long-haired cats. In other cases, more targeted medical interventions may be required, or an infertile male may have to be removed from the breeding pool.
