Uterine torsion and metabolic abnormalities in a cat with a pyometra

Abstract

A 6-year-old, intact female, Russian Blue cat was presented with abdominal distention, vaginal discharge, and a firm tubular structure palpable in the mid-abdomen. Serum biochemical abnormalities included hyperkalemia, hyponatremia, and azotemia. Exploratory laparotomy revealed a pyometra with uterine torsion; an ovariohysterectomy was performed.

A 6-year-old, intact female, Russian Blue cat was presented because of a 2-day history of lethargy, anorexia, abdominal distention, and vaginal discharge. The cat had no access to the outdoors and there were no other cats in the household. The last heat cycle was observed 6 wk prior to presentation and she had never been bred. The cat was up-to-date on vaccinations and was negative for feline leukemia virus and feline immunodeficiency virus.

Case description

On initial physical examination, the cat was assessed as 5% dehydrated and had a distended, painful abdomen with a palpable large tubular structure in the mid-abdominal cavity. A vulvar examination revealed purulent vaginal discharge. The cat had a rectal temperature of 36.6°C, a heart rate of 160 beats/minute, and a respiratory rate of 16 breaths/minute. Results from a rectal examination were normal.

Initial diagnostic procedures included a complete blood (cell) count (CBC), serum biochemical profile, abdominal radiographs, and abdominal ultrasonographs. The CBC showed a mature neutrophilia (14.2 cells × 10⁹ cells/L; reference range 2.5 to 8.5 × 10⁹ cells/L). The serum biochemical values revealed azotemia with a blood urea nitrogen (BUN) value of 25 mmol/L (reference range, 3.57 to 10.71 mmol/L) and a creatinine value of 300.6 μmol/L (reference range, 26.5 to 185.6 μmol/L). Hyperkalemia (potassium, 5.8 mmol/L; reference range, 3.1 to 4.9 mmol/L) and hyponatremia (sodium 137 mmol/L, reference range, 142 to 152 mmol/L) were also noted. The sodium:potassium ratio was 23:6. There was also a metabolic acidosis noted on the initial acid base results with a HCO₃⁻ valve of 12.9 mmol/L and a pH of 7.16. The systolic arterial blood pressure was 110 mmHg. Abdominal radiographs revealed a large tubular structure of soft tissue density in the abdominal cavity with an overall decrease in abdominal detail. There was no evidence of fetal ossification. Thoracic radiographs appeared to be normal. Abdominal ultrasonographs revealed a large, fluid-filled, left uterine horn. The right uterine horn was also fluid-filled, but much smaller than the left, and there was a 2-cm × 3-cm area of tissue density near the uterine body. A small amount of ascites was apparent. Ultrasound-guided aspiration of the ascitic fluid was performed. Results from analysis of the fluid were consistent with that of a pure transudate with a total protein of 10 g/L. On cytologic analysis, the fluid was acellular and showed no evidence of a septic peritonitis.

Initial treatment consisted of an IV bolus of 0.9% sodium chloride (B. Braun Medical, Irving, California, USA), 20 mL/kg body weight (BW), followed by 4 mL/kg/h BW as a constant rate infusion, enrofloxacin (Baytril; Bayer Corporation, Shawnee Mission, Kansas, USA), 5 mg/kg BW, IV, q24h, and ampicillin (Bristol-Meyers Squibb, Princeton, New Jersey, USA), 22 mg/kg BW, IV, q8h, to help prevent septicemia from a suspected pyometra.

Based on the high suspicion of a pyometra, the cat was prepared for surgery. Preoperative prothrombin and activated prothrombin times were within normal limits. The cat was premedicated with atropine (Butler, Columbus, Ohio, USA), 0.005 mg/kg BW, IV, and hydromorphone (Baxter Healthcare Corporation, Deerfield, Illinois, USA), 0.1 mg/kg BW, IV. Anesthesia was induced with propofol (Propoflo; Abbot Laboratories, North Chicago, Illinois, USA), 4 mg/kg BW, IV, and diazepam (Hospira, Lake Forrest, Illinois, USA), 0.5 mg/kg BW, IV, and maintained on isoflurane (2%) in oxygen. Lactated Ringer’s solution (Hospira, Lake Forrest) was administered, IV, at a rate of 10 mL/kg/h. A ventral midline celiotomy was performed. Approximately 50 mL of clear ascitic fluid was present; this was sampled and submitted for aerobic culture and sensitivity testing. Results from an exploratory examination of the peritoneal cavity were within normal limits with the exception of the uterus. The right uterine horn was mildly fluid-distended, but normal in color and position. The left uterine horn was severely fluid-distended and purple. A torsion of the left uterine horn was present. An ovariohysterectomy was performed, and the uterus was submitted for histopathologic examination. The torsion was not derotated prior to ligating the vessels, in an attempt to prevent release of endotoxins into the systemic circulation. The peritoneal cavity was lavaged and the abdominal wall was closed routinely.

The cat was maintained on IV fluids, ampicillin, 22 mg/kg BW, and enrofloxacin, 5 mg/kg BW. Hydromorphone, 0.04 mg/kg BW, IV, q4h, was given for postoperative pain management. Half of a 25 mcg fentanyl patch (Sandoz, Broomfield, Colorado, USA) was also placed to counter for postoperative pain. The electrolyte abnormalities were corrected with fluid therapy. On day 2, a repeat serum biochemical profile showed resolution of the azotemia. The cat was sent home on day 4 with instructions to the owner to administer amoxicillin-clavulanic acid (Clavamox; Pfizer, New York, New York, USA), 13.7 mg/kg BW, PO, q12h, and enrofloxacin, 5 mg/kg, PO, q24h, for 2 wk. Culture of a sample taken from the uterus at the time of surgery revealed a Corynebacterium sp. that was susceptible to all antibiotics tested. The culture of the ascitic fluid revealed no growth. Results from histopathologic examination of the uterus were consistent with a pyometra, neutrophilic endometritis, and cystic endometrial hyperplasia. The left uterine horn revealed that the wall was markedly edematous. The lumen contained bacterial colonies and some neutrophils. Areas of the endometrial lining were obscured by extensive necrosis and hemorrhage with infiltrates of neutrophils. Some endothelial glands were cystically dilated. The right uterine horn contained bacteria and some neutrophils. There was also prominent cystic endometrial hyperplasia.

On follow-up, 3 wk postoperatively, the cat was doing well and the CBC and serum biochemical values were normal. An analysis of urine showed normal concentrating ability of the kidneys (urine specific gravity, 1.055) and an inactive sediment. Results from a urine culture were negative.

Discussion

Cystic endometrial hyperplasia-pyometra is a disease that is mainly characterized by progesterone-induced hyperplasia of the endometrium; cystic dilatation of the endometrial glands; and inflammation of the uterus, with purulent content in the uterine lumen leading to several clinical signs (1). The clinical signs and pathogenesis of pyometra in cats has been well described in the literature (1–3). Cats are generally considered induced ovulators and are subjected to multiple cycles of estrogenic stimulation. If a queen ovulates but does not conceive, she may undergo pseudocyesis and eventually develop pyometra or endometritis (3). In this case, no known mating had occurred anytime prior to the occurrence of the pyometra. There may have been spontaneous ovulation that occurred in this cat. Spontaneous ovulation has been reported to occur in cats in response to a variety of visual, auditory, or olfactory stimuli in queens (4,5). Uterine torsion is defined as a twisting of the uterus or uterine horn perpendicular to its long axis (6). Uterine torsions are uncommon in cats and few cases have been reported in the literature (6–19). In cats, uterine torsions most commonly occur in late gestation or just before parturition. To the authors’ knowledge, this is the 1st reported case of a cat with pyometra and uterine torsion. However, a uterine torsion secondary to a pyometra has been referenced in a retrospective study of pyometras in cats (2). The etiology of uterine torsions is unknown, but it may involve stretching of the broad ligament from previous pregnancies, fetal movement, lack of uterine tone, flaccid uterine walls, uterine contractions, rough handling, lack of fetal fluids, and a long flaccid mesometrium (4).

The clinical signs of anorexia, lethargy, abdominal distention, and vaginal discharge in this case were similar to those in previous reports of feline pyometra (1–3). Polyuria and polydypsia (PU/PD) were noted by the owner, but they were not documented definitively, as a urine specific gravity was not obtained prior to surgery and the water consumption was not quantitated at home by the owner. Polyuria and polydypsia are not as commonly observed with pyometra in cats as they are in dogs; PU/PD has been reported to be present in only 9% of feline pyometra cases (1,2). Escherichia coli endotoxin is believed to be the underlying mechanism that causes PU/PD by interfering with Na+ and Cl− absorption in the loop of Henle, thereby reducing medullary hypertonicity and resulting in impaired water resorption. In addition, E. coli endotoxins block antidiuretic hormone (ADH) in renal collecting ducts, leading to obligatory polyuria with compensatory polydypsia (20). A Corynebacterium sp., not E. coli, was cultured from the uterine horn at the time of surgery; however, Corynebacterium spp. are rarely cultured from the fluid in the feline pyometra (1,2). A Corynebacterium sp. can be part of the normal flora in the feline reproductive tract (21,22).

Hyperkalemia and hyponatremia have been reported previously in a cat with a uterine torsion (11). In this case, the hyperkalemia was attributed to decreased excretion, due to renal failure, and transcellular shifting, due to a metabolic acidosis. The hyponatremia was attributed to “third-spacing” of sodium into the uterus and peritoneal effusion. It may also have been caused by a loss of isotonic-sodium and bicarbonate-rich fluid, with compensatory hyponatremia and acidosis, which is often seen with gastrointestinal disease. In a recent review of hyperkalemia and hyponatremia in cats, it was found that these electrolyte abnormalities are rarely caused by hypoadrenocorticism and are commonly caused by gastrointestinal disease, urinary disease, and endocrine disease (23). The electrolyte abnormalities in this cat were corrected with fluid support and ovariohysterectomy.

Abdominal ultrasonographs proved to be a useful diagnostic tool in this case. Previous reports have utilized ultrasonography as a diagnostic tool for discovering live or dead fetuses in the uterus (6,9). In this case, the abdominal radiographs indicated a fluid-filled uterus; this finding was confirmed by ultrasonography, which further indicated a lack of fetuses. Although the ultrasonography did not confirm a uterine torsion, it did show great asymmetry and tissue thickness that presumably was the torsion seen at surgery. Abdominal ultrasonography also enabled precision in the aspiration of ascitic fluid to rule out septic peritonitis. Primarily, the ascites was most likely due to increased portal hydrostatic pressure caused by obstruction or torsion of the mesenteric or uterine vessels and secondarily to increased permeability of the capillary endothelium due to inflammation of the uterus.