Tumors of the Vagina in Dogs

Tumors of the vagina are the second most common form of female reproductive tumor and can be either benign or malignant. Most vaginal lesions or tumors are non-cancerous leiomyomas or fibroleiomyomas, but certain malignant cancers can develop in the skin of the vagina as well so it is important to alert your veterinarian if you see signs of a tumor on or in your dog’s vagina. Canine transmissible venereal tumors, a type of cancerous canine tumor that can be spread from dog to dog by touch, can form in this area as well.

Tumors of the vagina and vulva are the second most common form of reproductive tumors in female dogs. Unspayed female dogs are more likely to develop these tumors.

Vaginitis is an inflammation of the vagina which can result in discharge, itching and pain. This inflammation can occur separately or concurrently with vaginal tumors. 

• Blood in the urine
• Difficulty giving birth or mating
• Excessive licking of genital area
• Mass on the vagina (either visible or palpable)
• Straining to urinate
• Vaginal discharge
• Vaginal odor
• Vulvar bleeding

Types

There are many types of tumors that can affect the vagina and vulvar area on dogs, both benign and malignant. The most common tumors to affect the vagina are leiomyomas and fibroleiomyomas; benign tumors of the smooth muscle that generally do not spread. Fibropapillomas, small, warty bumps that are caused by a viral infection, may also develop in this area. They tend to look similar to other tumors in this area, however they often regress spontaneously after a few months. Malignant tumors are rarer, but squamous cell carcinomas may also develop on the skin in this area, and clitoral adenocarcinoma may affect your canine’s clitoris. Canine transmissible venereal tumors are cauliflower-like, nodular or papillary and can also affect the genital area. They are often inflamed and ulcerated, making it quite contagious particularly if direct contact has occurred during mating, licking or rough play.

The causes of most cancers can be somewhat ambiguous although there are some things can increase the likelihood for cancers to develop:

• Advanced age
• Exposure to chemicals 
• Infection 
• Radiation exposure
• Genetics 
• Reproductive status (whether neutered or not)

There is a hormonal component to most vaginal tumors. The overwhelming majority of females that develop tumors in the vagina are unspayed, however tumors that do occur in spayed females have a higher incidence of being malignant. The exception to that rule in this group are the canine transmissible venereal tumors (CTVT). These tumors are actually a contagious canine cancer. It is transmissible by direct contact such as the type that is made during mating, licking or rough play. Generally, your canine’s immune system would recognize and eliminate cells from an outside source such as this, however when CTVT cells are introduced a state of rapid growth of the cancer cells begins and will last between three and nine months. Although CTVT is found in moist of the world, it is more prevalent in tropical and subtropical urban environments.

Initially, your veterinarian will need to get a full medical history of your pet as well as perform a physical examination, including a close examination of the tumors and the area surrounding them. A tissue sample will also be obtained so that it can be examined microscopically, as well as samples of any discharge from the vagina. A complete blood count, biochemistry profile, and urinalysis will also be requested to reveal any underlying or concurrent medical issues. Most of these growths are fairly simple to identify once the sample is viewed microscopically. To determine if there are other tumors your veterinarian may choose to perform a vaginoscopy. X-ray, ultrasound, or CT scans or may be used to ascertain if any tumors have spread further, and further analysis may be done in the lab to get more information from the tissue sample. If metastasis is suspected, your veterinarian may want to biopsy the local lymph nodes as well.

Ovariohysterectomy, the surgical removal of the uterus and ovaries, is the treatment of choice in these cases, as well as the removal of the tumor itself. This generally reduces the risk of more tumors forming due to hormonal means as well as allowing for the examination of the abdominal organs to check more clearly for metastasis. Surgery is completely curative for a majority of benign vaginal tumors as they should not spread and most are only locally invasive.

Malignant tumors of any type in this area will be treated aggressively. A radical vulvovaginectomy or perineal urethrostomy will be done to remove all possible cancerous tissue. Once the surgeon has removed all that he or she physically can, radiation and chemotherapy will be utilized in an attempt to destroy any new or hidden cancer cells as well as to prevent recurrence. Dogs are more tolerant of chemotherapy than most humans and only around 5% need hospitalization from the treatment itself. Although there is less reported hair loss in dogs than in people some breeds (English Sheepdog, Lhasa Apso, Maltese, Schnauzer, Shih Tzu, and Poodle) are more prone to hair loss than others. 

Complications from chemotherapy can arise, so your veterinarian will probably want to do regular checks on your dog’s liver and kidney enzyme levels. Pets are often sent home the same day after chemotherapy, and although most of the drug is metabolized within just a few hours, some remnants of it can remain in the blood for a few days. It is important to use gloves when dealing with bodily fluids and maintain good hand washing hygiene. Children, pregnant and nursing women and immunocompromised adults should avoid contact with the bodily fluids during that time. Your pet should be monitored closely for additional tumors during and after their chemotherapy treatments.