Infertility in Male Dogs
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. These causes can be broken down into three broad categories:
- failure to copulate (breed) or ejaculate
- poor semen quality
- prostatic diseases
What causes failure to copulate (breed) or ejaculate?
There are many reasons that 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."
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 behavior. 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. It is important to consider the setting of the attempted breeding. 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.
Physical conditions in the male may also lead to failure to copulate. This is often observed with any condition that causes discomfort in the spine or rear legs. These conditions may include spinal disease, arthritis, or trauma. Diseases of the penis may also result in painful copulation, leading to a reluctance to breed.
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 as it does in dogs with normal ejaculation. This makes the male physically incapable of ejaculating into the female.
What causes poor semen quality in dogs?
Poor semen quality can be caused by a number of defects. These include 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 disease accounts 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; therefore, prostatic disease can significantly impact fertility.
The majority of 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 with age. 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, fluid-filled prostatic cysts, and prostatic infections. Infectious prostatitis is caused by a number of bacteria, including E. coli, Staphylococcus, Streptococcus, Proteus, and Brucella canis. Any of these conditions can negatively affect fertility.
How will my veterinarian diagnose the cause of my dog's infertility?
Your veterinarian's workup will begin with a comprehensive physical examination. A rectal exam will be performed to assess your dog’s prostate gland and a general physical examination will be performed to assess for other conditions that may be associated with infertility.
A number of diagnostic laboratory tests will then be performed to look for possible underlying causes 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. Bloodwork 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 health, looking at sperm numbers, sperm movement, and sperm structure. 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 may 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 will my veterinarian treat my dog’s infertility?
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 that are making him reluctant to mount the female, addressing these issues (by using pain medication or other treatments) may be sufficient to permit breeding.
- Retrograde ejaculation can often be successfully treated using the injectable drug pseudoephedrine, which is administered prior to breeding.
- Problems with semen quality may or may not be treatable, depending on the underlying cause. Some cases are genetic, or inherited, 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 as needed to restore appropriate hormone levels.
- The treatment of 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, allowing the dog’s fertility to be successfully restored.
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