Most vaginal abnormalities are congenital, resulting from abnormal development of the paramesonephric ducts (also called the Müllerian ducts). In females, these embryonic structures evolve to form most of the female reproductive system, while in males they disappear. Abnormal development can lead to partial or complete aplasia or obstruction anywhere along the uterus, uterine tubes or the vagina. Persistent or imperforate hymen is the most common problem in dogs. This may take the form of stenosis, a horizontal narrowing of the vagina, or a vertical septum that divides the vagina into two chambers. Depending on the location of the abnormality, many dogs can be asymptomatic; in fact, clinical symptoms are only found in about .03% of dogs. The most common sign is difficulty or pain during breeding, but some dogs can also have protruding tissue, frequent vaginal infections, and incontinence due to fluids and urine being retained and pooling in the vagina. Another rare vaginal abnormality can occur when a hole forms between the vagina and the rectum. This is called a rectovaginal fistula. Fluids and feces may pass between these two areas spreading bacteria and preventing your dog from having normal bowel movements. Some feces may be expelled through the vulva, but many dogs still develop severe constipation or megacolon with rectovaginal fistula. This is usually a congenital condition, however, it can occur as a result of errors during colonic surgery. Vaginal strictures called adhesions may also be acquired through inflammation or from the development of cancerous lesions. Additionally, some dogs acquire vaginal hyperplasia, an external protrusion of vaginal tissue, as a result of excessive mucosa development during estrus, but this is temporary and the growth will disappear as hormone levels change.

Vaginal abnormalities in female dogs can cause problems with mating, persistent infection, and incontinence. Most vaginal malformations are congenital and present from birth, but a few conditions can be acquired.

Most symptoms will appear in young dogs especially around the first mating season.

These are the most common types of structural malformations in the vagina.

Acquired conditions may be caused by

The veterinarian will need to know your dog’s age, and whether she has been bred before. A detailed description of any symptoms will be helpful. Cellular cultures will be taken to identify infection, and determine what stage of the mating cycle your dog is in. Bloodwork is frequently normal, but urinalysis may show elevated levels of white blood cells from concurrent urinary tract infection. With rectovaginal fistula, the vaginal culture will show fecal contamination.

A physical examination will include palpitation and digital examination with an inserted finger. Many congenital structural abnormalities that are causing significant symptoms, especially vaginal septum, can be identified in this way. If no abnormalities are noted, Vaginoscopy (the insertion an instrument that can take a picture of the vagina), X-rays and ultrasound will help to identify abnormalities that are less obvious.

 

If the conditions isn’t causing a problem, most veterinarians don’t recommend treatment. With chronic symptoms of infection and incontinence, surgery is usually the best solution. Some problems directly related to breeding can be corrected with an ovariohysterectomy. Others may require surgical removal of the hymen membrane that is causing the problem. Dogs will typically stay in a veterinary hospital for at least a day and have a reduced period of activity when they come home. 

Rectovaginal fistulas also require surgery to correct the problem, especially if the dog also has an imperforate or obstructed anal canal which happens in many congenital cases. Diet change (usually a liquid diet) may be recommended until surgery can be performed. Dogs that have developed irreversible megacolon may need continued treatment to prevent constipation.

If the condition turns out to be cancerous, surgery will remove the tumor and chemotherapy may be prescribed to prevent metastasis. Further treatment may be needed if the cancer has spread to other parts of the body.

Most vaginal abnormalities only cause mild symptoms and dogs will make a full recovery with surgery. A rectovaginal fistula is more serious, but this condition is usually treatable with surgery. If megacolon has developed, long term management will be necessary. Your dog may need to take continual laxatives and follow a special diet that makes bowel movements easier. Cancerous conditions may be serious unless the problem is caught early. The veterinarian will discuss the likelihood of successful treatment upon diagnosis.