Research Updates: Clinicopathologic features of male cats with urethral obstruction

In this retrospective study from an urban veterinary teaching hospital, data from 223 male cats with urethral obstructions were evaluated to characterize clinical signs, electrolyte and acid-base changes, and renal parameters. Only 5% of the cats were purebred; most were domestic shorthaired or longhaired cats. Ninety percent of the cats were castrated, 83% were indoor pets, and 74.5% had no previous urethral obstructions. The median age was 4.7 years, and the median weight was 12.3 lb (5.6 kg).

Most of the cats had multiple clinical signs for three days including stranguria, dysuria, vocalization, lethargy, and anorexia. The median rectal temperature was 100.4 F (38 C); 39% of the cats were hypothermic (temperature < 100 F [37.8 C]), and 11% were hyperthermic (temperature ≥ 102.5 F [39.2 C]). Of the cats, 12% had heart rates below 140 beats/min. Severe hyperkalemia (> 8 mmol/L) occurred in 11.6% of the cats, though most of these cats lacked serious metabolic derangements as assessed by pH and pCO2, pO2, blood urea nitrogen, and creatinine concentrations.

Treatment consisted of intravenous fluids and urethral catheterization and included calcium gluconate, sodium bicarbonate, regular insulin, or dextrose to alleviate hyperkalemia. The mean duration of hospitalization was 1.8 days, and 205 cats survived to discharge. Twelve cats were euthanized at admission or during hospitalization because of costs, complications, or prognosis.

COMMENTARY

Feline urethral obstruction is a common, potentially fatal condition. This study characterizes the clinicopathologic features in cats acutely obstructed, most for the first time, that were treated at an urban center. Although infrequent, hyperkalemia was the primary metabolic change, and it inversely correlated with pH and bicarbonate, pCO2, sodium, chloride, and ionized calcium concentrations; it positively correlated with blood urea nitrogen and creatinine concentrations. These parameters should be monitored during treatment for hyperkalemia. The data presented confirm the authors' belief that most acutely obstructed cats are clinically stable at presentation and have excellent chances for recovery after appropriate treatment. It would be worthwhile to learn how many cats with urethral obstruction have a recurrence and to know the clinicopathologic features in cats with chronic or recurrent obstructions.

Lee, J.A.; Drobatz, K.J.: Characterization of the clinical characteristics, electrolytes, acid-base, and renal parameters in male cats with urethral obstruction. J. Vet. Emerg. Crit. Care 13 (4):227-233; 2003.