Introduction

Urethral obstruction is a common condition in domestic male cats. Many problems can occur due to the interruption of the urinary flow, such as acid-base and electrolytic changes that results in abnormalities in the myocardial cells potential action and, therefore, in electrocardiogram.

Objectives

The aim of this study was to characterize the electrocardiographic, biochemical, and hematological changes of cats with urethral obstruction.

Methods

Eighteen male cats with first urethral obstruction were evaluated in the clinical routine of Veterinary Medicine and Animal Science School - UNESP, Botucatu, SP.

Results

The most significant electrolytic change was hyperkalemia, in 76.5% of the animals; 17.7% were hypokalemic and 5.9% with normal potassium levels (5.4±1.7). The cats were azotemic, with serum urea (267.8±181.9) and creatinine (7.9±6.0) above reference range in 94.7% and 79% of the cats, respectively. It was observed as well hypoalbuminemia in 57.9% of cats (2.5±0.3). There was a marked leukocytosis in 79% of the cats (32147±16782) characterized by neutrophilia (29700±16444). In electrocardiogram 81.3% showed sinus rhythm, however, 6.25% presented sinus bradycardia and 12.5% sinus tachycardia. Other relevant findings were widened QRS complex (87.5% of the animals) and prolonged P-wave duration (62.3%) and Q-T interval (50%). There were also abnormalities such as ventricular extrasystole (6.3%), atrial still, right bundle branch block, and fascicular block (12.5%). The cats which presented serum potassium levels above 7.0 (22.2%) had as the most important irregularities fascicular block and atrial still.

Conclusions

It is important to monitor the cardiac rhythm in cats with urethral obstruction, since electrocardiographic changes are relatively frequent.