Causes of Infertility in Male Dogs
Infertility in dogs can be congenital (present at birth) or acquired during their lifetime. In many cases, failure to produce a litter is caused by improper breeding management and timing, rather than true infertility on the part of either the male or the female.
- Underdeveloped testicles (testicular hypoplasia)
- Undescended or retained testicles (cryptorchidism; if bilateral, the dog will be sterile; if only one retained testicle, the dog may be fertile)
- Persistent penile frenulum (a piece of skin remains attached between the prepucial sheath and the penis, preventing normal extrusion of the penis and successful mating)
- Phimosis (the prepucial opening is too small for the penis to come out of it and accomplish a breeding)
- Chromosomal abnormalities (intersex disorders; these involve the intermingling, to varying degrees, of the characteristics of both sexes in one animal, including anatomical form, reproductive tissue and organs and sexual behavior)
- Anatomical abnormalities of the penis
- Anatomical abnormalities of the prepuce
Infertility in male dogs can also be acquired after birth, for a number of reasons. These include:
- Testicular or scrotal trauma
- Testicular or scrotal infection
- Testicular inflammation (orchitis)
- Testicular torsion (extremely serious; potentially fatal)
- Testicular degeneration
- Fracture of the bone of the penis (os penis)
- Infection or inflammation of the prostate gland (prostatitis)
- Trauma to the prostate gland
- Inflammation anywhere along the male genital tract (by Brucella canis or other infectious microorganisms)
- Castration (neutering)
- Immune-mediated diseases or disorders
- Metabolic diseases or disorders
- Prolonged exposure to certain drugs (steroids; anti-cancer drugs/chemotherapy; estrogen; androgen; progesterone; certain antibiotics; others)
- Exposure to environmental and chemical toxins
- High fever
- Prolonged exposure to temperature extremes
- Sexual overuse
- Inbreeding (the mating of very closely related dogs; mother to son, father to daughter, etc.)
Excessive sexual activity is a significant cause of temporary infertility in male dogs. Most authorities recommend that a dog bred on 3 consecutive days should be rested for the following 2 days, at a minimum. Some males can be bred every other day and maintain a high sperm count, but they still will require rest periods to prevent impotence (loss of libido or sex drive).
One of the reported hormonal causes of canine infertility is hypothyroidism, which usually is an acquired condition. Low thyroid hormone levels affect both sperm count and sex drive. Diabetes mellitus can also cause infertility by decreasing the sperm count in affected dogs. Hypogonadism is a poorly understood disorder that involves a decrease in one or more sex hormones that cause abnormalities in sperm numbers and motility. Diseases or disorders of the pituitary and adrenal glands are other acquired hormonal causes of infertility in male dogs.
Low testosterone levels can lead to a low sex drive. Testosterone is a hormone that is produced by the testes and is critical to the male libido. Testicular diseases, including cancer and infection, can diminish or destroy a dog’s sex drive. Testicular sertoli cells produce estrogen, which acts to neutralize the effects of testosterone. Sertoli cell tumors are uncommon but they do happen in domestic dogs and can contribute to infertility.
In some males, infertility is caused by failure of the internal urethral sphincter to contract (close) when the dog ejaculates. When this happens, semen is ejaculated upstream into the dog’s urinary bladder, rather than out the urethra and into the female’s vagina. This condition is called “retrograde ejaculation.”
Psychological factors can contribute to canine infertility, in both males and females. Some male dogs are scolded and punished by their owners for showing sexual behavior (“humping”) and/or aggression towards other dogs or people. This can create an unpleasant association with mating. Some bitches can be extremely aggressive during breeding, which may traumatize participating males and make them fearful of sexual activity. Dogs raised exclusively indoors with people may be reluctant to mate simply because they are uncertain about their rank with other dogs. Physical pain, in the genitalia or in the legs, can also inhibit a male dog’s desire to breed.
Prevention of Infertility
It is impossible to make meaningful generalizations about effective ways to prevent infertility in male dogs, because the causes can be so variable. However, exposure to temperature extremes – hot or cold – should be avoided. Care should be taken in selecting appropriate bedding materials and when bathing male dogs, so that their genital areas are not irritated or traumatized. Male dogs should not be bred daily for any prolonged period of time, and inbreeding should be avoided by all but the most seasoned of breeders. Breeding animals should be kept away from environmental and household toxins and should not be given drugs for longer than medically necessary. Perhaps most importantly, infertility can be prevented by sound, thoughtful, well-managed breeding programs and practices on the part of both the stud and the bitch owners.
The most common cause of infertility (“failure to produce puppies”) is poor or inadequate breeding management practices – especially improper timing and coordination of matings. It takes about 60 days for sperm to mature within the canine reproductive tract. As a result, infertility caused by testicular problems will take roughly 2 months to resolve, if resolution is possible.