Feline · Urinary · Emergency medicine
Feline urethral obstruction
Male cat straining with a large firm painful bladder. Hyperkalemia with bradycardia is the lethal problem; treat the potassium before spending time on the catheter.
Obstruction produces postrenal azotemia, metabolic acidosis, and hyperkalemia. ECG changes progress from tall tented T waves, to prolonged QRS, to loss of P waves and a sine wave. Emergency management is calcium gluconate to stabilize the myocardium, isotonic fluids, and dextrose with or without insulin to shift potassium intracellularly. Then sedate, decompress by cystocentesis if needed, and pass a urinary catheter. Anticipate postobstructive diuresis and match fluid output. Recurrence prevention centers on environmental modification, wet diet, increased water intake, and litterbox management; perineal urethrostomy is reserved for repeated obstructions or urethral trauma.