The terms "vaginal prolapse and hyperplasia" refer to the protrusion of oedematous vaginal tissue through the rima vulvae; the terms "vaginal eversion" and "vaginal protrusion" are often used, but these are incorrect. Vaginal prolapse is a disorder that affects many species of domestic animals, including bovines, ovines and caprines; these species are generally affected by a complete prolapse, i.e. one that concerns the entire thickness of the vaginal wall. Such a prolapse may also involve contiguous organs, such as the bladder or the uterus.
In queens, vaginal prolapse is a very rare occurrence and can arise in oestrus or anoestrus. In bitches, the eventuality of a complete vaginal prolapse is quite rare and occurs as parturition draws near. The reduction of progesterone and the increase of oestrogens does in fact favour hyperaemia and oedema of the vaginal tissue; therefore, in the canine [3] species, it is more correct to speak generically of partial vaginal prolapse.
In 1967, Schutte proposed a classification of the disease in 3 degrees. A first-degree prolapse is a moderate eversion of the vaginal floor without protrusion of vaginal tissue from the vaginal slit. In the second-degree prolapse there is an eversion of the cranial floor and side walls of the vagina which, protruding from the labia, assume a typical "pear" or "tongue"-like shape. The third-degree prolapse ultimately affects the entire circumference of the vaginal canal; externally it presents itself in the shape a "doughnut" (Fig. 1).
SIGNALMENT AND MEDICAL HISTORY
In bitches, the frequency of vaginal prolapse is rather low compared to other disorders of the reproductive system; the frequency varies according to the degree of the prolapse (full or partial), to the stage of the oestrus cycle and to some individual characteristics (being sexually intact or gonadectomized, size, genetic line).
The complete vaginal prolapse occurs in 8-12% of cases and is accompanied, as already mentioned, by hormonal changes that characterize the last few days before parturition.
In 73-86% of cases the prolapse is partial and occurs during the follicular phase (pro-oestrus/oestrus); on rare occasions the prolapse can occur during dioestrus or in the early phase of pregnancy.
Vaginal prolapse usually occurs in sexually intact, young (mean 21 months) female dogs. No actual breed predisposition is recognized, although several authors report a higher frequency in large breed dogs (60%) compared to small ones (10%). An increased susceptibility of some genetic lines has also been ascertained, especially among brachycephalic dog breeds, a fact that supports the hypothesis of a possible hereditary predisposition of the disease.
At the anamnestic examination, owners report the recent appearance of a visible mass, in the vulva, that can take various shapes and sizes and that can be intermittent; other symptoms include anorexia and alterations in urination (dysuria, strangury and pollakiuria).
AETIOPATHOGENESIS
The aetiologic and pathogenetic mechanism of vaginal prolapse has not yet been fully elucidated; bitches suffering from prolapse do not in fact present problems of hyperoestrogenism or fertility (in the absence of other reproductive disorders).
Both complete and partial vaginal prolapse are favoured by a higher concentration of oestrogens, which are responsible for the relaxation of pelvic ligaments, the oedema of perivaginal tissues and relaxation of the vulvar and perivulvar muscles. Such hormone-induced changes are indispensable for a vaginal prolapse to occur.
In reality other secondary factors seem have a role, such as a congenital weakness of the perivaginal tissues, tenesmus, the violent separation of the male during coitus and huge differences in size between animals during mating. Among the causes of a complete prolapse, vaginal traumas or neoplasms have also been reported.
SYMPTOMS
The common symptom in patients with vaginal prolapse is the presence of a mass projecting from the vulvar labia. In fact, depending on the degree of the prolapse, the mass can range from easily visible to hardly perceptible, thus explaining why most first degree vaginal prolapses escape the observation of the owners. Another feature, which complicates the identification of the prolapse, is the fact that the mass may protrude intermittently, usually following a temporary increase in intra-abdominal pressure (tenesmus). As already mentioned, the prolapsed portion may assume different shapes and sizes depending on the degree of the prolapse.
The conditions of the subject are generally good, while the state of the prolapsed vaginal tissue can vary widely; oedema is always present, while in more severe cases ischaemia and necrosis of the tissues may be present, making them easily susceptible to lacerations. In these cases, the sensory function may appear depressed and the subject may present anorexia and pyrexia; vaginal discharges of various types can also be present.
DIAGNOSIS
The presence of clearly visible vulvar and vaginal alterations must not be misleading; before issuing a diagnosis of vaginal prolapse some differential diagnoses are to be considered.
The first differential diagnosis is represented by vaginal cancer. The elements useful for distinguishing between the two diseases are essentially the signalment, the medical history and the characteristics of the mass. Vaginal prolapse, as already mentioned, generally occurs in young, sexually intact bitches, and in a particular stages of the oestrus cycle, such as the pro-oestrus and oestrus. Vaginal cancer, instead, affects both sexually intact as well as gonadectomized bitches, and usually in older-aged animals. Neoplastic masses are independent of the oestrous cycle and do not regress during dioestrus and anoestrus, as happens in the case of prolapse. In the presence of a neoplasm the vaginal mass does not have a precise origin, while prolapses always originate from the vaginal floor, cranially to the urethral meatus. In doubtful cases a cytological examination is recommended.
In cases in which the prolapse occurs shortly before or during parturition, a physical examination, particularly of the reproductive tract, possibly accompanied by an ultrasound examination, is necessary to distinguish the vaginal prolapse from a cervical or uterine prolapse. In these cases it is necessary to identify any foetuses that may be present and assess their conditions of vitality, by means of abdominal palpation and ultrasound.
A careful overall physical examination must clearly be performed, in order to monitor the clinical conditions of the subject, including a blood test and a urine analysis.
TREATMENT
The choice of treatment is essentially based on the outcome of the clinical examination, which is aimed at establishing the degree of the prolapse and the general conditions of the animal.
Partial and intermittent prolapses generally resolve spontaneously at the beginning of dioestrus, and therefore do not require any particular treatment.
The prolapsed vaginal tissue must however be kept clean and protected from dehydration; the use of lubricating and hyperosmotic substances may be indicated in order to reduce the oedema and encourage a spontaneous repositioning of the organs. In subjects prone to excessive licking and self-traumatism, the use of an Elizabethan collar and, in the worst cases, of tranquillizers are useful.
In cases of complete vaginal prolapse close to the time of parturition, the condition of the mother and foetuses must be monitored; in such case hospitalization in a clinic which provides reproductive services is recommended. It is always necessary to verify the presence of spontaneous micturition and, if obstructed, bladder catheterization must be provided.
As for the cases of partial prolapse during pro-oestrus or oestrus, the outcome is conditioned by the stage of the oestrous cycle. In subjects in which spontaneous ovulation is imminent (progesterone>4 ng/ml), the prolapse will resolve spontaneously following the reduction in blood concentration of the oestrogens. In cases in which ovulation is not imminent (progesterone <2 ng/ml), the ovulation must be pharmacologically induced with the administration of GnRH (2.2 micrograms/kg i.m.) or hCG (1000 IU per animal i.m.). Regression of the prolapse should take place within one week after treatment. The use of progestogenic substances, such as megestrol acetate, is not recommended.
The manual repositioning of the prolapsed organs and subsequent suturing of the vulva can lead to a positive outcome, but it is scarcely feasible in view of the pain and vulvar trauma that can result.
In cases in which the resolution does not occur either spontaneously or after hormone treatment, a non-conservative surgical treatment is possible, with amputation of the prolapsed vaginal portion. Surgical treatment is more common in cases of third-degree prolapse, in which the vaginal mucosa appears to be badly compromised.
The only treatment which is definitively resolutive is an ovariectomy/ovariohysterectomy; in fact, in view of the hormonal nature of the disease, with other treatments frequent cases of relapse have been reported. Ovariectomy/ovariohysterectomy are therefore recommended whenever possible, as they ensures the removal of the hormonal stimulation that is the primary cause of the prolapse, thus totally reducing the chances of relapse.
PROGNOSIS
In terms of survival, the prognosis is guarded only in cases of severe impairment of the general conditions of the subject. In terms of function, the prognosis depends on the treatment used. Given the high incidence of recurrence (66%), non-conservative surgical treatment with ovariectomy/ovariohysterectomy is always recommended.
In the case of subjects of high genetic value used for breeding, medical treatment generally ensures the restoration of the reproductive function of the animal, although it cannot in any way prevent the possibility of recurrence.
Suggested readings
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- JohnstonSD, Kustritz MVR, Olson PNS (2001)Disorders of the canine vagina, vestibule, and vulva. In: Johnston SD, Kustritz MVR, Olson PNS (Eds.) Canine and Feline Theriogenology. WB Saunders: 233-235.
- JohnstonSD, Kustritz MVR, Olson PNS (2001)Disorders of the feline vagina, vestibule, and vulva. In: Johnston SD, Kustritz MVR, Olson PNS (Eds.) Canine and Feline Theriogenology. WB Saunders: 472.
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- Troge CP (1970) Vaginal prolapse in the bitch. Mod Vet Pract, 51: 38-41.
- Schutte AP (1967) Vaginal prolapse in the bitch. J S Afr Vet Med Ass, 38: 197-203.