Infertility (Male) in Dogs

Possible symptoms of infertility include fever, bloody discharge from penis, failure to ejaculate, and pain/discomfort. Treatment varies depending on the underlying cause, but can range from medicinal to surgery. Prognosis depends largely on the underlying cause, some cases have a complete recovery while others have no viable treatment options at this time. Male dogs who should be evaluated for infertility are those who impregnate less than 75% of female dogs who are known to be fertile, provided that correct breeding management and ovulation timing has occurred. Infertile dogs may be consistently infertile or may have been fertile previously but have experienced a decline in successful impregnation. 

Infertility in male dogs may result from a variety of causes. These causes can be broken down into the following categories: infectious or inflammatory, physical, traumatic, immune mediated, chemical, behavioral, genetic or chromosomal, endocrine, neurologic, tumors, and metabolic. 

• Fever
• Uneasiness or discomfort
• Bloody discharge from penis
• Painful ejaculation
• Swelling/pain of testes
• Depression
• Pain in lumbar region
• Retrograde ejaculation (sperm is expelled into the bladder instead of the urethra)
• Changes in libido
• Failure to ejaculate
• Refusal to breed

Types

Cases of male fertility can be broken into categories by cause. The following categorizations can be used to identify male fertility:

• Infectious or inflammatory: This may affect specific parts of the reproductive system or be more general.
• Physical: Infertility may be caused by anatomic defects. These defects can be congenital (at birth) or acquired.
• Traumatic: Traumatic events that affect the scrotum may affect fertility.
• Immune mediated: This can affect the production of sperm if antibodies are produced against the testicle, essentially leading to self-destruction.
• Chemical: Exposure to certain chemicals or use of certain medications may impact fertility.
• Behavioral: In many behavioral cases, a change in libido or failure to ejaculate can be observed.
• Genetic or chromosomal: These regularly result in sterility but may occasionally cause subfertility.
• Endocrine: Endocrine causes are related to hormone imbalances that cause infertility.
• Neurologic: Infertility at the hand of neurologic causes has to do with changes in nerve transmission.
• Tumors: These can affect fertility by changing temperature regulation or taking up space and affecting functionality.
• Metabolic: These causes may affect the reproductive system secondarily through their impact on other organs.

• Infectious or inflammatory: Infection or inflammation may affect the testes, epididymis (a duct behind the testis through which sperm passes), spermatic cords (cord-like structure formed by the vans deferens), prostate, penis, and prepuce. Inflammation of the prostate is the most common site of inflammation in the male. Infection may be caused by bacteria, including staphylococcus, streptococcus, Escherichia coli, Proteus Pseudomonas, Brucella canis, Pasteurella, and Mycoplasma. 
• Physical: These abnormalities may include missing segments of the reproductive tract, which could cause an absolute sperm deficiency if both sides are affected, or a decrease in sperm count if only one side is affected. Granulomas (plugs of sperm) may cause blockage to the ejaculatory tract. Obesity may cause overheating of the testes, affecting fertility. Fluid accumulation in the scrotum as a result of peritonitis (inflammation of the stomach) or leakage of fluid can also affect fertility.
• Traumatic: Trauma can alter testicular function or sperm production and ejaculation as the result of thickening of the scrotum, fluid accumulation in the scrotum, or bleeding in the testes or spermatic cords. Penis trauma can also have scarring which can affect ejaculation.
• Immune mediated: Breakdowns in the reproductive system can cause the reproductive system to turn itself, ultimately resulting in a form of self-destruction. With time, normal testicular function may return if the body is able to recover.
• Chemical: Environmental toxins, medications, anabolic steroids, and pesticides or insecticides may affect fertility. 
• Behavioral: Some behavioral causes of infertility include fear or anxiety, inappropriate discipline for male sexual behavior, timidity or confusion, or territorial issues. 
• Genetic or chromosomal: There are really no treatments for genetic infertility, though related members of their bloodline should be evaluated and heavily considered when determining breeding purposes.
• Endocrine: Possible hormone imbalances that affect fertility include steroid hormones (such as testosterone and estrogen), pituitary hormones, thyroid hormones, or others.
• Neurologic: Nerve transmission can be affected by problems with the spine or vertebral column, affection ejaculation. 
• Tumors: Types of tumors in the testes include seminomas, Sertoli cell tumors, interstitial cell tumors, lymphoma, and teratomas. Castration is typically suggested.
• Metabolic: Types of metabolic diseases that may inadvertently affect the reproductive system include diabetes, hypothyroidism, and epilepsy.

Your veterinarian will ask you to detail your dog’s medical history and any symptoms or problems that you’ve noticed. Your veterinarian will also rule out poor breeding management as the cause of presumed infertility. This may be evaluated by determining if the female has had reproductive success before, and if they have not, possibly by breeding to another female to see if this female becomes pregnant. Additional diagnostic tests may include:

• Physical exam
• Reproductive exam
• Endocrine profile, which will measure hormones to determine a cause of the infertility
• Ultrasound, used to identify abnormalities and examine the prostate gland
• If prostate infection is the cause, palpation of the prostate can aid in diagnosis by revealing enlargement of the prostate and pain. 
• Breeding soundness exam, in which a sperm sample is collected and sperm count and characteristics are evaluated.
• Microscopic examination and bacterial culture of sperm and urine
• Testicular biopsy

• If infection is the cause, antibiotics can usually treat the problem. In some cases, antibiotic treatment may be long term. In severe cases, removal of the infected reproductive part may be necessary.
• If sperm plugs are to blame, regular collection may be necessary.
• If obesity is to blame, weight reduction measurements should be taken.
• Retrograde ejaculation can be treated through medication to close the urethral sphincter prior to breeding/collection.
• If the cause is chemical, removal of the chemical or discontinuation of the medicine will likely return your dog to normal function.
• If a hormonal balance is to blame, administration of hormone supplements such as human chorionic gonadotropin, human menopausal gonadotropin, gonadotropin releasing hormone, thyroid replacement hormones, or others, may return your dog to normal functionality.
• Anti-inflammatories may aid in neurologic causes resulting from spine-related issues.
• Artificial insemination may be an alternative for breeding, should the male be unable to regain vitality.
• If a tumor is the cause, castration of the testicle is the most common course of action. The remaining testicle may still be able to produce sperm.

Recovery and management depend largely on the underlying cause of the condition. Some causes, such as chemical or behavioral causes, can have a complete recovery. Others, such as genetic causes, currently have no treatments available.