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Infertility What is infertility and what causes it? Infertility is the inability of an individual to reproduce, and it can occur in both males and females. There are a number of causes, which can broadly be grouped into the following categories: (1) Congenital (a physical defect that the animal is born with, that prevents it from breeding) (2) Infectious (an infection that the animal has acquired, that damages the reproductive tract) (3) Hormonal (a disease that interferes with the animal's hormones so that it cannot breed) In addition there may be disorders of behaviour, as well as just improper animal management, in which case there is no true infertility but rather a misunderstanding of animal reproduction. As with humans, animals must have reached a certain body weight before they are able to reproduce. A malnourished animal may be infertile, as may an animal that is excessively physically active, such as a racing greyhound, just as a human athlete may stop her reproductive cycles during heavy training. When will my dog first be able to reproduce? Bitches reach puberty at 6-24 months depending on when they reach mature body weight. However, some normal dogs do not reach puberty until they are 2-3 years old, and in some greyhounds it may be 4-5 years. Hence a bitch that is apparently unable to reproduce may be normal rather than infertile. The testicles of male dogs should have descended by 6-7 weeks of age, but they do not reach puberty until 9-10 months, or later for larger breeds. Congenital causes of infertility: Congenital causes of infertility include: (1) ovarian aplasia/ hypoplasia: this is absence or failure of development of the female’s ovaries. It is very rare. A blood test performed by your veterinary surgeon will detect ovarian activity, or an operation to look for the presence of ovaries can be performed. (2) Abnormal sexual differentiation: this is when the animals sex organs fail to develop normally. For example an animal may be born looking like a female but instead of having ovaries, it has small testicles hidden inside its abdomen. Such animals usually have abnormal sex chromosomes: real females have the sex chromosomes "XX", real males have "XY" whereas an abnormally developed animal could be "XXX" or "XXY." (3) Penis deformity: various deformities of the male’s penis can occur leading to infertility. Also abnormal testicular development can occur. Infectious causes of infertility: Infectious causes of infertility include: (1) Brucella canis infection: this is a bacterial infection of dogs which can cause infertility (in both males and females) or abortion. It can also cause fever and headaches in humans. Infection can be by ingestion of placental, mammary or vaginal material, or it can be transmitted venereally. Treatment involves antibiotics but is not always successful. Control involves regularly testing breeding animals, and never introducing a dog to a breeding kennel unless it has tested negative for this bacterium. (2) Herpes virus infection: this has been associated with abortions and stillbirths in bitches. It may also be involved in the inability to conceive, but this is unclear. (3) Bacterial endometritis: this is infection of the womb lining by bacteria. Diagnosis can be made by a veterinary surgeon who will test for presence of bacteria. Treatment involves antibiotics. (4) Cystic endometrial hyperplasia (CEH): this occurs in older females. It is not solely an infectious disease, but bacterial infection contributes to the condition. There are cysts in the lining of the womb, due to the action of sex hormones acting on the uterus, and there are also usually excessive numbers of bacteria. If untreated pyometra (a potentially fatal womb infection) can develop. Treatment involves antibiotics to kill the bacteria, and drugs to inhibit the sex hormones and delay the onset of the next oestrus until the CEH has gone. Hormonal causes of infertility: Hormonal causes of infertility include: (1) Hypothyroidism: this is reduced activity of the thyroid gland, a gland in the neck. This means that there is reduced production of thyroid hormone, and this can influence reproductive cycles causing infertility. The condition is most common in young to middle-aged dogs of larger breeds. Predisposed breeds include Golden Retrievers, Irish Setters, Doberman pinschers, boxers, dachshunds and Wolfhounds. (2) Hyperadrenocorticism ("Cushing's disease"): this is over-activity of the adrenal glands resulting in excessive production of the naturally occurring steroid cortisol. It occurs in middle-aged to older dogs. (3) Hypoadrenocorticism: this is under-activity of the adrenal glands resulting in insufficient cortisol production. The condition is most common in middle-aged (2-5 years) female large-breed dogs. (4) Pituitary insufficiency: this is a rare disease, most commonly seen in German Shepherd Dogs with hereditary dwarfism. The pituitary gland is a gland in the brain that normally releases Growth Hormone, but it also produces hormones that control reproduction.
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