Vaginal hyperplasia in dogs: swelling and treatment

Overview

In vaginal hyperplasia, swollen lining initially bulges into the vaginal cavity. A larger protrusion may become visible between the lips of the vulva.

Severity is classified into 3 clinical types.

Estimates of frequency reach as high as 8–10% of bitches. Indian veterinary hospitals identified 94 cases among 9,236 gynaecological disease cases, or 1.02%. That figure therefore describes gynaecological cases, rather than all bitches in the area.

Vaginal hyperplasia can remain internal, without a visible external lump. True vaginal prolapse is less common and may be associated with difficult labour, for example.

Causes

Oestrogen causes the vaginal lining to swell during a season. In vaginal hyperplasia, the usual increase in blood flow and swelling is exaggerated. However, the precise mechanism is unknown.

Blood oestrogen in an affected bitch is not necessarily higher than in a healthy dog. Unusual tissue sensitivity to oestrogen is one possible explanation. Swelling begins on the vaginal floor in front of the urethral opening.

Thickening of the lining and underlying tissue increases the protrusion. An initial internal bulge can progress to partial or complete circumferential protrusion. Symptoms may also occur around giving birth as the hormonal balance changes.

Normal bloody discharge during a season originates in the uterus. The oestrogen responsible is produced in ovarian follicles.

An individual prolapse case has also been described after oestrogen medication used to induce a season.

Risk factors

The condition is most common in young bitches during their first seasons. In reported cases, 73–86% occurred during the first, second or third season. A typical patient is an unspayed bitch with continuing ovarian hormone activity.

Short-muzzled breeds have been overrepresented among patients. Boxers and large dogs also occur frequently in case descriptions. However, precise breed predispositions have not been established in comparative studies.

In the Indian group of 94 patients, 48.94% were Labrador Retrievers. Pugs made up 24.47% of the same group. Of the patients, 43.62% were 1–2 years old. Those over 4 years accounted for 13.83%.

Of the same 94 dogs, 35.11% were in pro-oestrus at examination. Oestrus accounted for 60.64%. Dioestrus accounted for 4.25%.

A surgical comparison included an experimental group of 7 bitches and a comparison group of 6. Of the operated bitches, 8 were in their first season. The 5 examined in later seasons had already had protrusion during a previous cycle.

Typical symptoms

You may notice the following signs:

• A visible bulge or tissue mass protrudes through the vulva during a season.

• Your dog tries to lick the exposed lining and may damage it.

• Urination becomes difficult if the protruding tissue obstructs urine flow.

• The bitch resists mating despite apparently being at the appropriate stage of her cycle.

• The exposed tissue surface becomes irritated, damaged or inflamed.

Difficulty urinating is fairly uncommon in ordinary vaginal hyperplasia. A smaller change may remain entirely inside the vulva. Visible tissue can range from a tongue-shaped protrusion to a ring-shaped mass.

Tissue damage can cause local pain, particularly when inflammation or injury persists.

Complications and consequences

Exposed lining can be damaged by friction or the dog's own attention. Secondary infection may develop in damaged tissue. Severe loss of blood supply can cause death of the protruding tissue.

Backward displacement of the bladder with prolapse has also been described in an individual dog. Mild disease may settle as the cycle progresses without a procedure. Estimates of recurrence after spontaneous resolution range from 66–100%.

Vaginal hyperplasia itself does not usually bleed, but injured tissue may do so.

Diagnosis at the vet

Diagnosis combines the history, clinical examination and laboratory tests when needed. The vet establishes the relationship to the reproductive cycle. Examination assesses whether the protruding tissue is a mucosal fold or another lesion.

Severity of the change

In type I, swollen tissue on the vaginal floor remains inside the vulva. In type II, tissue from the floor and side walls protrudes in a tongue or pear shape. In type III, the entire circumference protrudes as a ring with a central opening.

The external urethral opening lies on the lower surface of the protruding tissue. Difficulty urinating is considered when planning care. Inflammation and possible tissue death affect the need for surgery.

Cell samples and distinguishing other conditions

Cornification of superficial cells in a vaginal sample indicates an oestrogen effect. Blood-tinged secretions typical of a season also help identify the cycle stage. Sexual behaviour is another observation used to assess the hormonal phase.

A vaginal tumour is a key alternative cause of a similar protrusion. An enlarged clitoris or uterine prolapse may also look like a mass around the vulva. A visible tissue lump alone therefore does not establish its origin.

Cell samples may also identify inflammatory cells or abnormal cells suggesting a tumour. Vaginoscopy, examination of the vagina with a camera, helps locate surface damage. It can also establish whether bleeding comes from the vagina or the direction of the cervix.

Ultrasound can investigate possible uterine or ovarian changes when needed. A full blood count can assess anaemia associated with bloody discharge. Blood biochemistry may help investigate other systemic diseases in the same situation.

Local palpation may reveal vaginal narrowing or an abnormal band of connective tissue. A distinctly one-sided lesion also raises suspicion of a local tumour. A leiomyoma, a smooth muscle tumour, may become apparent as seasonal swelling decreases.

More than 70% cornified superficial cells is consistent with a marked oestrogen effect. This may come from the ovaries or external hormone exposure. Bloody discharge may also originate in the urinary tract. A clotting disorder can cause similar bleeding too.

Vaginal and vulval tumours occur at an average age of 7–10 years. Whether discharge is continuous and how heavy it is are established as part of the history.

Treatment

Treatment depends on the extent of protrusion and the bitch's reproductive status. The aim is to keep exposed lining clean and protected from further damage. A protective collar prevents licking and self-injury.

Treating a mild change

A small internal change may settle without surgery. Swelling often decreases once oestrogen no longer dominates the cycle. Type I and II changes may shrink spontaneously as the hormonal effect declines.

The vet may use a topical antibiotic ointment when needed. In some cases identified before ovulation, hormonal induction of ovulation may be considered. The vet may choose gonadotrophin-releasing hormone or chorionic gonadotrophin for this purpose.

Surgery and preventing recurrence

Tissue that blocks urination or has died may need surgical removal. In type II, excess tissue beneath the lining can be removed. Severe type III changes may be treated by removing protruding tissue around the entire ring.

Local tissue removal alone may be followed by recurrence in the next cycle. Removing the ovaries removes the hormonal influence sustaining recurrence. Swelling usually settles within 7–10 days after ovary removal.

In type III, tissue removal is combined with removal of the ovaries. The ovaries may be removed alone or together with the uterus. Removing only the uterus can instead leave ovarian hormone activity intact.

Manual replacement of tissue and a tightening suture around the opening have been used. This method is not recommended because of pain and vulval damage. If a prolapse will not stay in place, surgical fixation of the uterus may be considered.

Removing the ovaries and uterus during a season carries a greater bleeding risk. Mating soon after this surgery can damage the vaginal surgical site. Possible concurrent uterine disease is also considered when choosing the procedure.

Ovary removal alone can generally use a smaller incision than removal of both ovaries and uterus. It also involves fewer potential bleeding sites. Removing the ovaries alone may reduce the risk of accidentally closing off a ureter too.

Pain relief and investigating infection

Pain from tissue trauma may be treated with a non-steroidal anti-inflammatory drug prescribed by the vet. Some severely painful cases may also need an opioid. Culture of inflammatory discharge helps target any antimicrobial treatment required.

Prevention

Removing the ovaries prevents recurrence associated with the hormonal cycle. Vaginal hyperplasia does not usually recur after complete removal of the ovaries and uterus. Breeding from an affected dog is not recommended.

Inherited susceptibility is suspected because cases occur within the same family lines. However, vaginal hyperplasia itself does not necessarily make a bitch infertile. Some Boerboel breed clubs recommend assessment for vaginal hyperplasia as a breed-specific health check before breeding.

Health information about siblings, parents and offspring is also collected to support breeding choices.

Some Boerboel breed clubs recommend openly sharing all health test results, including imperfect ones.

Important for dog owners

Note when the season began and when the protrusion became visible. Record whether it has occurred during previous seasons or births. Photograph the change to monitor size without unnecessary handling. Tell the vet whether your dog urinates normally and can reach the area to lick it.

Ask which tissue forms the lesion and whether there is surface damage. Agree when review will take place and which changes to monitor at home. Discuss treatment of the current protrusion and a plan for the next cycle. If your dog has already been spayed, bring the surgical report to clarify whether the ovaries remain.

A protrusion that shrinks as a season ends may return at the next season. Protection prescribed by the vet prevents self-inflicted damage during healing.

Frequently asked questions

Is vaginal hyperplasia the same as a tumour?

Vaginal hyperplasia is swelling and tissue overgrowth associated with an oestrogen effect. However, a vaginal tumour can appear as a similar protruding lump. Examination also considers an enlarged clitoris or uterine prolapse, for example. Cell samples can help identify inflammation and abnormal tumour cells.

Can the protrusion disappear by itself after a season?

Mild type I and II changes may shrink as the oestrogen effect decreases. However, the problem may recur in the next cycle. Exposed tissue is kept clean and protected from self-injury. Local removal alone does not always prevent later recurrence.

Why does the vet ask about urination?

The external urethral opening lies on the underside of the protruding tissue. Difficulty urinating is fairly uncommon. Nevertheless, the protrusion can block normal urine flow. An obstructive lesion may require surgery. Impaired tissue circulation is considered in the same assessment. Possible tissue death is also evaluated.

Does spaying cure vaginal hyperplasia?

Removing the ovaries prevents hormonally driven recurrence. Swelling may settle within about 7–10 days of the procedure. Severe type III changes also need removal of the protruding mass. Removing only the uterus may preserve ovarian hormone activity.

Can an affected bitch have puppies?

The condition does not necessarily prevent conception if no other reproductive disease is present. Nevertheless, breeding from an affected dog is not recommended. Inherited susceptibility is suspected because it occurs within family lines. The condition may also recur during later seasons.