Many of the medical conditions affecting a female dog’s reproductive tract are extremely serious and can even be fatal, although risk of these disorders can be reduced by spaying. In contrast, few reproductive disorders affecting the male are life-threatening.

Dangers During Birth
There are several risks to a female dog when giving birth. If she fails to have successful contractions or has difficult labour, the pups may need to be delivered by Caesarean section. After birth, there is a risk of haemorrhage, infection, prolapse or rupture of the uterus, or eclampsia – a life-threatening loss of calcium from the body. If your dog has difficulties during or after birth, seek urgent veterinary help. X-ray analysis may be used to identify a closed pyometra; this dangerous condition, caused when pus builds up in the womb, requires urgent surgery.

Male infertility can occur as a consequence of prostatic or testicular disease, an underactive thyroid, or even a prolonged high fever. Female infertility is difficult to assess, although hormonal blood tests during oestrus may be useful. Each female has her own idiosyncratic oestrous cycle, however, and the most common reason for unsuccessful mating is miscalculation of the correct time for mating.

Female Reproductive Tract Disorders
Womb infection or pyometra This is potentially life threatening, and usually occurs after an oestrous cycle. Bacteria multiply in the womb and create pus. If the cervix remains open, the pus escapes through the vagina and out of the vulva. This is known as an “open pyometra”, and is relatively easily diagnosed and treated. If the cervix is tight, however, pus builds up in the womb; this is called a “closed pyometra” and clinical signs develop quickly. A dog with pyometra has increased thirst and a decreased appetite. She rests more and may or may not have a vaginal discharge. Untreated, this leads to collapse and shock. If a dog has a closed pyometra, immediate surgery is needed to remove the womb.
Vaginitis and juvenile vaginitis  Vaginitis (inflammation of the vagina) in adult female dogs causes discomfort, and affected dogs persistently lick their vulva. Some young pups develop a sticky, green-yellow vaginal discharge that dries into a hard crusty wick in the hair on the tip of the vulva. This condition, known as juvenile vaginitis, almost always spontaneously clears when a pup has her first season. If your pup is affected, postpone spaying until three months after her first season.
Mammary tumours  In most cases, mammary tumours appear as hard, pebble-like mobile masses under the skin near teats, but the most aggressive form causes rapid, painful swelling in breasts in the groin area. Removal and examination of a lump is the only guaranteed way of diagnosing mammary tumours. Neutering a female dog can reduce the risk of mammary tumours: if bitches are spayed before their first season, the risk is negligible, and even spaying after the first season still reduces the risk by over 99 per cent. However, spaying a female dog after she has had about six oestrous cycles has no effect on the risk of her developing mammary tumours.
Male Reproductive Tract Disorders
Discharge from the sheath, (balanoposthitis)

A male dog normally produces a cream-yellow coloured lubricant in the sheath (smegma). Injury or infection to the sheath or penis can cause increased redness, excessive drip that may be foul-smelling, and licking. To treat, the sheath is flushed with warm saline or dilute antiseptic � this reduces the quantity of discharge. If the problem is due to bacterial infection, the dog is treated with antibiotics.

Penis stuck out of sheath (paraphimosis)

During an erection, the bulbourethral gland on a dog’s penis can swell so much it is too wide to retract into the sheath. If the erection is prolonged, the penis becomes dry and cannot be withdrawn. To treat this condition, lubricate the penis with water-soluble jelly and slide it back in its sheath. If this is not possible, keep it moistened with lubricant and get veterinary help.

Undescended testicles

There is a high incidence of cancer in undescended testicles. Abdominal testicles may be surgically removed. Partly descended testicles that have passed through the inguinal ring should be monitored for changes in texture or size, and removed if and when necessary. Because this condition is inherited, dogs with partly or completely undescended testicles should not be used for breeding.

Scrotal or testicular enlargement

The most likely cause of testicle enlargement is a testicular tumour. To treat, tumours are surgically removed and identified by a pathologist. Malignancy is very rare. Infection or injury from dog bites, frostbite, or contact with corrosive chemicals can also cause painful enlargement. A moist scrotal skin infection causes weeping skin damage that heals into a hard, carapace-like scab, giving the impression of testicle enlargement. Penetrating injuries are treated with pain killers and antibiotics.

Prostate problems

The prostate may become infected when there is either bladder or urethra infection. All prostates increase in size with time, reaching maximum size usually between six and ten years of age. This swelling pushes upon the floor of the rectum, causing a bottleneck for stool to pass through. Initial signs of “benign hyperplasia” include difficulty passing stools. In rare instances hyperplasia can produce small to enormous prostatic cysts that can cause rectal obstruction. Prostate tumours are uncommon. A dog may be treated with injections of delmadinone, but if severe, hyperplasia is reduced by castration.