VETERINARSKI ARHIV 69 (3), 161-165, 1999

ISSN 1331-8055 Published in Croatia

A case of urolithiasis in a captive brown bear

Huben Hubenov, Dinko Dinev*, Nadya Zlateva, Nikolay Goranov, Dinyo Bakalov, and Tsveta Filipova

Department of Surgery and Radiology, Faculty of Veterinary Medicine,
University of Thrace, Stara Zagora, Bulgaria

* Contact address:
Prof. Dr. Dinko Dinev,
Department of Surgery and Radiology, Faculty of Veterinary Medicine, Thracian University, Student's Campus, 6000 Stara Zagora, Bulgaria,
Phone: 359 42 302 85; Fax: 359 42 451 01

Hubenov, H., D. Dinev, N. Zlateva, N. Goranov, D. Bakalov, T. Filipova: A case of urolithiasis in a captive brown bear. Vet. arhiv 69, 161-165, 1999.

ABSTRACT

The subject of the present report is an interesting case of urolithiasis in a captive brown bear (Ursus arctos) - a urolith found in the urethra that caused urinary bladder rupture, severe uraemia and peritonitis. The clinical signs, the schedule of general anaesthesia, the successful operative intervention and the outcome of the operation are all described in detail.

Key words: urolithiasis, urinary bladder rupture, brown bear, Ursus arctos, surgery

Introduction

Urolithiasis is a common disease in almost all animal species, with a higher incidence in male individuals (BOVÉE et al., 1985). An especially serious problem is encountered when uroliths are lodged within the urethra and an obstruction occurs.

There are no reports for incidence of this disease in bears (WEDLICH, 1982).

The subject of the present report is an interesting case of urolithiasis (urolith within the urethra of a captive brown bear) that caused rupture of the urinary bladder, severe uraemia and peritonitis. The clinical signs, the schedule of general anaesthesia, the operative intervention and the outcome of the operation are all described in detail.

Materials and methods

A captive male brown bear (Ursus arctos), 6 years old, 181 kg, kept for public attraction, was referred to the Surgical Clinic of the Faculty of Veterinary Medicine, Stara Zagora, on 10 October 1997. A radiograph of the abdomen was made. Prior to the operation, blood was sampled for routine examinations (haematology, blood urea nitrogen).

Taking into account the high risk for the life of the patient, blood was sampled every 30 min from the previously catheterised cephalic vein for determination of acid-base and blood gas status (ABL-3, Radiometer, Denmark) during the operation.

Results and discussion

The first clinical signs were noted a month before the first visit to the clinic - decreased appetite, depression, anxiety, retention of urine, bloody urine. An unsuccessful attempt at catheterisation of the urinary bladder had been performed.

Twenty-eight days after the first observation, the bear was hospitalised in the clinic with the following anamnesis: total refusal of feed, dorsal recumbency with elevated limbs, a "sitting dog" posture. Urination was absent for 4 days, although a slight improvement in general condition was observed.

The most striking sign was a pronounced flat belly, especially in dorsal recumbency. Body temperature was 35.3 °C. After tranquillisation with Rompun^(r) (Bayer, Germany) at a dose rate of 0.75 mg/kg i.m., lateral radiography of the hips was performed. This revealed 3 dense homogenous shadows localized 4-5 cm behind os penis. The first had a diameter of 10-12 mm, and the other two 3-4 mm.

The principal deviations in the blood parameters were haemoconcentration (hematocrit 0.57 l/l), leukocytosis (24.0 G/l) and high blood urea nitrogen values (27.0 mmol/l).

The radiological picture and the clinical and paraclinical results served to diagnose urolithiasis (calculi urethrales) and to propose the performance of a urethrotomia.

The operation was made under general inhalation anaesthesia, maintained for 3 hours. The schedule of anaesthesia included pre-medication with xylazine (Rompun^(r), Bayer) 0.75 mg/kg i.m. and ketamine hydrochloride (Imalgen^(r), Rhône Mérieux) 5 mg/kg i.m. Fifteen minutes later, anaesthesia was induced with a further dose of ketamine (5 mg/kg). Because the swallowing reflex was not overcome, thiopental was slowly venously injected at a dose of 1.25 mg/kg until an effect was observed. After intubation, the inhalation anaesthesia was maintained with 4.0-3.5-3.0% halothane and an oxygen flow of 4 l/min using a close circulatory breathing circuit. The schedule of anaesthesia was found to be effective for this case and eight minutes after the cessation of the halothane, the animal recovered in a sternal position.

Despite the severe uraemia, the principal clinical parameters did not change significantly during the operation. Immediately after the induction of anaesthesia, body temperature was 35.0 °C, pulse rate 120 beats/min, respiratory rate 12 beats/min. The last two parameters were determined using the esophageal stethoscope. At hour 2, body temperature slightly decreased to 34.2 °C, the pulse rate remained 120 beats/min and the respiratory rate became 15 beats/min.

The operative interventions were consecutively as follows: urethrotomy, laparotomy, vesicoraphy. Urethrotomy was performed just behind os penis, near the location of the uroliths, following the classical sequence of the operation.

After the removal of uroliths, the urinary bladder was catheterised, although the amount of the poured urine was minimal. This led to the thought that the urinary bladder had spontaneously ruptured. This hypothesis was confirmed after median laparotomy. After the dissection of the peritoneum and opening of the abdominal cavity, 10-15 litres of fluid with the characteristic odour of urine and yellow-reddish colour flowed out under pressure. The fluid accumulated in the abdominal cavity was slowly aspirated in order to prevent a collapse. The diagnosis was then confirmed after inspection of the urinary bladder. The bladder defect was closed with Gambee suture (KNECHT et al., 1981), Vycril 3. The abdominal cavity was washed several times with warm rivanol solution (1:1000), and aspirated via a vacuum pump.

The catheter within the urethra was attached to the preputial skin by several interrupted sutures. The urethral mucosa was closed by a two-stage suture of Schmiden and an interrupted Lembert suture using Vycril 2-0 suture material. The skin was sutured with silk suture 2 using an interrupted suture.

The dynamics of change in acid-base parameters are presented in Table 1.

Table 1. Changes in the acid-base values of a brown bear with urolithiasis and rupture of the urinary bladder before and after surgery, and treatment with sodium bicarbonate solution

Data showed an increasing decompensated metabolic acidosis that required urgent correction, achieved via the venous administration of 500 ml sodium bicarbonate solution.

For correction of the electrolyte balance and restoration of blood volume, a massive volume-replacing fluid therapy was performed via a venous, slow injection of 2.0 litres 0.9% sodium chloride; 2.0 liters Darrow solution and 500 ml 5% glucose.

After the final restoration of the passability of the urinary ducts, a slow venous administration of 20% manitol at a dose rate of 0.5 g/kg was performed for stimulation of diuresis and improvement of renal perfusion.

The therapy resulted in a successful outcome. Twenty days later, during a control examination, the animal was found to be in a very good state.

The lack of data in the literature for urolithiasis in the bear (WEDLICH, 1982) do not permit us to speculate and interpret the clinical and paraclinical signs from a comparative point of view. However, the leading clinical signs that could be used for diagnostics are frequent and difficult urination, depression, subnormal body temperature, characteristic posture in recumbency, flat belly (after rupture of the bladder). The most consistent paraclinical parameters were the haemoconcentration, leucocytosis, the very high blood urea nitrogen levels, the high degree of decompensated metabolic acidosis (BOVÉE, 1983). Those changes result mostly form the developing peritonitis, occurring after the urinary bladder rupture and in a lesser degree than the urolithiasis itself.

In conclusion, it could be stated that this wild animal species is characterized by a high resistance and high compensatory possibilities in overcoming disorders that could be critical for individuals of another species. That fact is most probably related to the higher, evolutionally determined adaptivity of the organism to risk conditions.

References

BOVÉE, K. C. (1983): Metabolic disturbances of uremia. In: BOVÉE K. C. (ed.) Canine Nephrology, Harwal Publishing Co., Media, PA.

BOVÉE, K. C., A. ROSIN, B. L. HART (1985): Pathophysiology and Therapeutics of Urinary Tract Disorders. In: SLATTER D.H. (ed) Textbook of Small Animal Surgery, W.B. Saunders, Co, NY, 1733-1752.

KNECHT, C., A. ALLEN, D. WILLIAMS, J. JOHNSON (1981): Fundamental techniques in Veterinary Surgery, Saunders, Philadelphia.

WEDLICH, V. (1982): Grossbären (Ursidae) in der veterinärmedizinischen Literatur. Inaugural Dissertation, Tierärztliche Hochschule. Hannover.

Received: 27 October 1998
Accepted: 20 July 1999

Hubenov, H., D. Dinev, N. Zlateva, N. Goranov, D. Bakalov, T. Filipova: Mokracni kamenci u smedeg medvjeda iz zatocenistva - prikaz slucaja. Vet. arhiv 69, 161-165, 1999.

SAZETAK

Predmet ovog prikaza je zanimljiv slucaj mokracnih kamenaca u smedeg medvjeda (Ursus arctos) iz zatocenistva. Urolit u mokracnici bio je uzrocnik prsnuca mokracnog mjehura, jake uremije i upale potrbusnice. Detaljno su opisani klinicki znakovi oboljenja, tijek opce anestezije, operativni zahvat i uspjesni ishod lijecenja.

Kljucne rijeci: urolitijaza, mokracni kamenci, prsnuce mokracnog mjehura, ruptura mokracnog mjehura, smedi medvjed, Ursus arctos, kirurgija