Infertility in Male Dogs

By Malcolm Weir, DVM, MSc, MPH; Catherine Barnette, DVM

Breeding, Diagnosis, Medical Conditions, Treatment, Pet Services

What is infertility?

Infertility in a male dog is defined as the inability to produce a successful pregnancy in a fertile female, even with multiple breedings near the time of ovulation.

What causes infertility in male dogs?

There are many possible causes of infertility in male dogs that can be broken down into three broad categories: failure to copulate (breed) or ejaculate, poor semen quality, and prostatic disease diseases

What causes failure to copulate or ejaculate?

There are many reasons why a male dog may have difficulty with breeding or ejaculation. Some of these reasons are behavioral, while others are due to physical or medical factors.

A common behavioral cause of infertility is the dynamic between the male and female; if a male dog is introduced to a non-receptive or aggressive female, a refusal to breed is a normal result. Additionally, a male dog that is anxious due to his surroundings, is inexperienced, or is not sexually mature may also refuse to copulate with a receptive female. Attempting to promote breeding on a slippery floor may lead to apprehension, as the male feels less secure in his footing and may be reluctant to mount the female.

"...if a male dog is introduced to a non-receptive or aggressive female, a refusal to breed is a normal result."

Physical conditions that cause discomfort in the spine or rear legs can result in a reluctance to copulate. These conditions may include spinal disease, arthritis, or trauma. Diseases of the penis may also result in painful copulation, causing reluctance.

A condition known as retrograde ejaculation may be responsible for an inability to ejaculate. In dogs with retrograde ejaculation, sperm enters the bladder with ejaculation instead of traveling to the tip of the penis. This makes the male physically incapable of ejaculating into the female.

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What causes poor semen quality in dogs?

Poor semen quality can refer to low sperm counts, the complete absence of sperm in the semen, abnormal sperm motility (movement), and abnormal sperm morphology (structure). Decreased sperm number and quality will decrease the likelihood of successful conception, even with appropriate copulation and ejaculation. Possible causes of decreased semen quality include hormonal imbalances, certain medications, fever from systemic infection, and numerous diseases of the testicles.

What prostatic diseases can affect fertility in dogs?

"Prostatic diseases account for 25-40% of all male reproductive problems."

Prostatic diseases account for 25-40% of all male reproductive problems. The prostate gland produces some of the fluids found in semen and contributes to the forward movement of semen during ejaculation. Many older intact male dogs will eventually develop a condition known as benign prostatic hypertrophy. This condition is caused by the effects of sex hormones over time, resulting in the prostate gland becoming significantly enlarged. This prostatic enlargement can lead to infertility. Other types of prostate disease that can affect infertility include prostatic tumors, which may be benign or malignant, prostatic cysts, and prostatic infections. Infectious prostatitis is caused by certain bacteria, including E. coli, Staphylococcus, Streptococcus, Proteus, and Brucella canis.

How will my veterinarian diagnose the cause of my dog's infertility?

Your veterinarian will begin with a comprehensive physical examination that will include a rectal exam to assess your dog’s prostate gland. Diagnostic laboratory tests will then be performed to look for the underlying cause(s) of your dog's infertility. These tests typically include:

1. Complete blood cell count and biochemistry panel. These blood tests assess the function of your dog's internal organs and look for signs of infections or autoimmune disease. Blood work can reveal systemic (whole-body) diseases that may be affecting your dog’s fertility.

2. Urinalysis. Evaluating the chemistry and microscopic appearance of your dog’s urine may reveal evidence of infection or other causes of infertility.

3. Semen testing. The semen can be evaluated for sperm quality and quantity. It may also be cultured to test for the presence of a bacterial infection. Additionally, measuring levels of certain enzymes found within the semen can provide an indication of reproductive health.

4. Brucellosis titer. This blood test allows your veterinarian to specifically test for the presence of Brucella canis, one possible infectious cause of prostatic disease.

5. Ultrasound. Ultrasonography is often used to evaluate the internal structure of the testicles and prostate gland, looking for evidence of infection, benign disease, or cancer.

6. Hormone testing. Blood tests may be used to assess your dog’s levels of testosterone, luteinizing hormone, follicle-stimulating hormone, thyroid hormone, and/or cortisol. Each of these hormones play a role in male infertility.

7. Other testing. Depending on the results of these preliminary screening tests, your veterinarian may recommend additional, more specialized testing to determine the cause of your dog’s infertility.

How is infertility in male dogs treated?

Treatment will depend on the underlying cause of your dog’s infertility.

Behavioral factors resulting in a reluctance to breed can often be addressed by changing the breeding environment, using a different female, or considering alternative measures such as artificial insemination.

If your dog has physical factors causing reluctance to mount the female, these issues will need to be addressed.

Problems with semen quality may or may not be treatable, depending on the underlying cause. Some cases are genetic, meaning that there is no successful treatment. In many dogs, however, poor semen quality can be addressed by removing drugs that may be damaging to sperm and providing hormone supplements to restore appropriate hormone levels.

"Brucellosis, in particular, causes irreversible infertility; treatment is not recommended, and these dogs should no longer be bred."

The treatment of a prostatic disease depends on the underlying cause. While many infectious causes of prostatic disease can be treated, treatment does not always restore fertility. Brucellosis, in particular, causes irreversible infertility; treatment is not recommended, and these dogs should no longer be bred. Benign prostatic hypertrophy can often be successfully treated with a drug called finasteride (Proscar®, Propecia®), allowing the dog’s fertility to be restored.

Supportive care, such as ensuring good quality nutrition for the stud dog. Certain forms of nutritional supplementation may be helpful in restoring fertility.

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