True vaginal prolapse associated with retroflection of the urinary bladder in a bitch

Abstract

True vaginal prolapse is rare in bitches and is most likely to occur near whelping. A 2-year-old intact female Brazilian mastiff, 39.5 kg, had a true vaginal prolapse associated with urinary bladder retroflection; the female was in estrus, and concomitantly had diarrhea for 3 d, plus vaginal hyperplasia, and ultimately a vaginal prolapse. Ultrasound examination and retrograde urethrocystography were extremely important for detection and identification of the position (retroflection) of the urinary bladder within the prolapsed vagina. These tools, therefore, are recommended for a conclusive diagnosis and surgical planning, to avoid trans- and postoperative complications, e.g., urethral damage or bladder rupture. Prompt diagnosis and surgical correction enabled a favorable prognosis and rapid postoperative recovery, avoiding complications or ultimately death of the dog.

Introduction

True vaginal prolapse, a rare condition in dogs, is characterized by protrusion of edematous vaginal tissue through the opening of the vulva; it differs from partial prolapse due to the exposition of the external cervical os (1). It occurs most often during the peripartum period when the ratio of serum concentrations of progesterone and estrogen are inverted (2); it is rarely reported at other reproductive stages (3,4).

Although the etiology is not fully defined, pelvic muscle relaxation, mesovarian flaccidity, and tenesmus are considered predisposing factors (5). Development of a true vaginal prolapse may also occur as a sequela of decompensated vaginal hyperplasia, which may develop in bitches in estrus, as an excessive response to physiological estrogen concentrations (6). In addition, prolapse of other organs, such as the urinary bladder, uterine body, or distal portion of the colon, may also occur (1,7). Increased intra-abdominal pressure may contribute to retroflection of the urinary bladder (8); this has been reported mainly in elderly male dogs, with a lower incidence in bitches and cats (8,9).

Herein we describe a very unusual case of true vaginal prolapse associated with retroflection of the urinary bladder in a nulliparous, non-pregnant bitch. Written informed consent for publication of this case report was obtained from the owner.

Case description

A 2-year-old intact female Brazilian mastiff weighing 39.5 kg was referred to the Obstetrics and Animal Reproduction sector of the Veterinary Hospital “Governador Laudo Natel” at UNESP Jaboticabal, with a history of a bloody vaginal discharge for approximately 1 wk, a swollen vulva, and male attraction. The owner described seeing a mass protruding from the vulva a few days after the onset of the vaginal discharge. According to the owner, the mass had gradually enlarged for a few days and then increased abruptly in size 1 d before the consultation. The dog had been fed primarily sheep offal and had had diarrhea for the last 3 d.

Physical examination revealed a reddish mass (14.6 × 12.5 × 10.1 cm; length × width × height) projecting through the vulva, with edema and some congestion, but no evidence of hemorrhage or necrosis (Figure 1). The perineal region had adherent feces, consistent with the history of diarrhea. The dog was recumbent, in poor body condition (BCS: 3/9), heart rate: 120 bpm, tachypnea, moderate dehydration (8%), non-reactive lymph nodes, normal colored mucosa, and a capillary refill time of 2 s. Blood samples were collected for hematology and serum biochemistry (Tables 1 and 2). There was leukocytosis (24 600 total leukocytes/μL; reference range (RR): 6000 to 18 000 μL) due to neutrophilia (19 680/μL), and hypoalbuminemia (1.99 g/dL) and hyperglobulinemia.

Figure 1.

Mass measuring 14.6 × 12.5 × 10.1 cm (length × width × height) protruding through the vulva, characterizing true vaginal prolapse. An arrow indicates the urinary meatus with a urethral catheter.

Table 1.

Hematological parameters for a female Brazilian mastiff at admittance.

Parameter	Value at admittance	Lab reference values
Red blood cells (/μL)	5.49 × 106	5.5 to 8.5 × 106
Hemoglobin (g/dL)	14.6	12 to 18
Hematocrit (%)	41	37 to 55
VCM (fL)	74.7	60 to 77
HCM (pg)	26.6	19.5 to 24.5
CHCM (g/dL)	35.6	30 to 36
Platelets (/μL)	403 × 103	175 to 500 × 103
White blood cells (/μL)	2.46	6 to 17 × 103
Basophil (%)	00	—
Basophil (/μL)	0	Rare
Eosinophil (%)	4	1.66 to 7.35
Eosinophil (/μL)	984	100 to 1250
Rod neutrophil (%)	00	0 to 1.75
Rod neutrophil (/μL)	00	0 to 300
Segmented neutrophil (%)	80	50 to 67
Segmented neutrophil (/μL)	1.97 × 103	3.0 to 11.5 × 103
Lymphocyte (%)	13	16 to 28
Lymphocyte (/μL)	3.2 × 103	1.0 to 4.8 × 103
Monocyte (%)	3	2.5 to 8.0
Monocyte (/μL)	738	150 to 1350

Table 2.

Serum biochemistry parameters for a female Brazilian mastiff at admittance.

Parameter	Value at admittance	Lab reference values
Creatinine (mg/dL)	0.8	0.5 to 1.5
Urea (mg/dL)	45	21 to 59.9
Total protein (g/dL)	8.91	5.4 to 7.1
Albumin (g/dL)	1.99	2.6 to 3.3
Globulin (g/dL)	6.92	2.7 to 4.4
ALT (UL)	13	21 to 102
Alkaline phosphatase (UL)	26	20 to 156

Ultrasonographic examinations of the abdomen and prolapsed mass were performed (Siemens S2000 with 9 MHz linear-array transducer; Siemens Medical Solutions, Erlangen, Germany). The ovaries and uterus were not detected in the abdominal cavity, being displaced along with the prolapsed mass. Within the prolapsed structure, the retroflected bladder was identified, with its usual shape, thickened echogenic walls, regular internal margins, and a lumen filled with anechoic content with discrete cellularity. The uterus had a slightly heterogeneous wall and was visualized surrounding the urinary bladder (Figure 2). Continuous retrograde urethrocystography was conducted via urethral catheterization (Figure 1) to confirm the integrity of the urethra. The urethra was intact and the urinary bladder was observed (Figure 3). Based on clinical, radiographic, and ultrasonographic findings, a diagnosis of a true vaginal prolapse associated with retroflection of the urinary bladder was made (Figure 4).

Figure 2.

Ultrasound image of the prolapsed mass. A — Retroflected urinary bladder with moderate liquid repletion, usual shape, thickened echogenic walls, regular internal margins, and lumen filled with anechoic content with discrete cellularity. B — Uterus with slightly heterogeneous parenchyma, surrounding the urinary bladder.

Figure 3.

Retrograde urethrocystography of the protruded mass, in the right laterolateral projection. Note the intact urethra and an oval structure of the amorphous shape, compatible with the urinary bladder.

Figure 4.

Digital representation, in latero-lateral view of the true vaginal prolapse associated with retroflexion of the urinary bladder. A — Everted and externalized vaginal mucosa; B — Retroflected urinary bladder; C — Uterine body projected into the prolapsed mass; D and E — Left and right ovaries, respectively. The arrow indicates the external urinary meatus.

A decision was made to resolve this condition surgically. Anesthesia included midazolam (0.2 mg/kg, IV) and propofol (4 mg/kg, IV) followed by isoflurane in O₂. For antimicrobial chemoprophylaxis, cefazolin (30 mg/kg, IV) was administered. The bitch was placed in dorsal recumbency, scrubbed, and prepped. A celiotomy was done and the uterine horns were visualized, projecting into the prolapsed mass (Figure 4). Protruding tissues were cleaned and washed with 0.9% saline solution and external mechanical pressure on the prolapsed tissue concomitant with uterine traction through the laparotomy incision were used to reposition the uterus into the abdominal cavity and to correct the retroflection of the urinary bladder (Figure 5 A–C). An ovariohysterectomy was performed, but cystopexy was not done, as the urinary bladder wall was friable.

Figure 5.

Stages of uterine and urinary bladder repositioning. A — External mechanical pressure of prolapsed mass by an assistant concomitantly with uterine traction through linea alba incision by the surgeon to reduce true vaginal prolapse and bladder retroflection; B — Uterine horns and urinary bladder returning to their anatomical position, while there is still some external mechanical pressure being exerted by the assistant; C — Return of the anatomical position of the entire uterus and urinary bladder.

Post-operative treatment included tramadol hydrochloride (4 mg/kg, q8h, for 5 d), dipyrone (25 mg/kg, q8h, for 5 d), cephalexin (30 mg/kg, q12h, for 10 d), meloxicam (0.1 mg/kg, q24h, for 3 d), and ranitidine hydrochloride (2.2 mg/kg, q12h, for 10 d). The bitch recovered uneventfully after surgery and no reoccurrence of the vaginal prolapse was observed after 1 y.

Discussion

True vaginal prolapse is a rare condition in the bitch, usually occurring during or shortly after whelping (10,11) when serum concentrations of progesterone decrease and those of estrogen increase (12). The unusual aspect of this case was a true vaginal prolapse in a dog during proestrus/estrus, in the absence of pregnancy. In addition, the bitch had previous signs of vaginal hyperplasia, which is not common prior to vaginal prolapse.

Potential predisposing conditions for true vaginal prolapse in the female dog include increased intra-abdominal pressure (13,14), dystocia (7), forced separation during copulation (12), constipation (11), intestinal parasitism (15), weakness of the pelvic floor muscles, and advanced age (1). The current case, however, was young and nulliparous, 2 conditions that do not predispose to vaginal prolapse. This true vaginal prolapse was primarily attributed to the estrogenic phase of the estrous cycle, which promotes relaxation of pelvic ligaments, edema of perivaginal tissues, and relaxation of the vulva and perivulvar muscles, and other tissues (16,17). Furthermore, concomitant diarrhea likely increased intra-abdominal pressure and contributed to this disorder.

No specific changes in hematology and clinical chemistry are described in cases of vaginal prolapse; however, anemia can occur following hemorrhage and leukocytosis can indicate an infection (18,19). In dogs, neutrophils are the initial leukocytes recruited in response to inflammation; therefore, in this species, leukocytosis is usually due to neutrophilia, whereas leukopenia is related to a reduced number of neutrophils (20). Neutrophilic leukocytosis occurs in various pathological conditions, but may also be a response to acute stress (21). Hypoalbuminemia can occur in several situations, e.g., deficiency of dietary protein, parasitism, intestinal malabsorption syndrome, and hemorrhage. In addition, albumin is an acute-phase negative protein, which tends to decrease its serum concentration during an inflammatory process, due to inhibition of its synthesis by proinflammatory cytokines (22). In the present report, leukocytosis was attributed to contamination of the prolapsed mass and/or by stress, whereas hypoalbuminemia was attributed to poor nutrition (primarily sheep offal) and low body condition, exacerbated by inflammation.

Urinary bladder catheterization followed by retrograde urethrocystography, to assess the integrity of the urethra and avoid trans- and post-operative complications, has apparently not been reported in cases of true vaginal prolapse associated with urinary bladder retroflection; however, in our view, this was a crucial tool for prognosis and surgical planning. The pelvic urethra may be secondarily injured by traumatic urethritis, which can often trigger luminal stenosis (23).

In the present case, the pelvic urethra was retroflected as a result of the retroflection of the urinary bladder. Even though it caused partial luminal stenosis, it did not impair urination, thus not requiring bladder emptying or the use of excretory urography. However, failure to detect urinary bladder retroflection could have been followed by urethral obstruction, urethral damage, and stenosis. Furthermore, in our opinion, excretory urethrocystography was essential for a comprehensive diagnosis and prevention of complications.

Although the most common treatment for urinary bladder retroflection is cystopexia (24), this was not done due to the extremely thin and friable mucosa of the urinary bladder, which could have led to severe postoperative complications (e.g., dehiscence or rupture).

Prognosis depends on the degree and time of occurrence (6). A vaginal prolapse may be accompanied by hemorrhage, infection, or necrosis of prolapsed tissue. If not treated quickly, affected animals can become hypotensive and/or septicemic, which can cause death (25). Regardless, the prognosis of urinary bladder retroflection is favorable as long as the patient is promptly evaluated and there are no extensive lesions. However, with urethral involvement, the prognosis may be unfavorable (26). In the present case, the dog was not in shock nor did it have substantial preoperative bleeding, indicating a favorable prognosis.

In conclusion, in this rare case of true vaginal prolapse associated with urinary bladder retroflection, ultrasonography and retrograde urethrocystography were useful for a conclusive diagnosis and surgical planning and to avoid trans- and postoperative complications, e.g., urethral damage and/or bladder rupture. Prompt diagnosis and surgical correction enabled a favorable prognosis, avoiding postoperative complications and potentially death. CVJ