Historical and Physical Parameters As Predictors of Severe Hyperkalemia in Male Cats with Urethral Obstruction

Objective: To evaluate selected historical and physical parameters as predictors of hyperkalemia in male cats with urethral obstruction.Design: Retrospective study.Setting: Veterinary teaching hospital.Animals: Two hundred and twenty-three male cats.Interventions: None.Measurements and main results: The metabolic derangements of 223 male cats that presented with urethral obstruction from 1997 through 1999 were reported in a companion article. Approximately 12% of the cats had multiple, life-threatening metabolic derangements. In the present study, historical and physical parameters were evaluated as predictors of hyperkalemia (K+>= 8.0 mmol/L) in cats with urethral obstruction. The 4 historical parameters significantly associated with hyperkalemia were: first time obstruction, outdoor status, anorexia, or vomiting. The 5 physical parameters significantly associated with hyperkalemia were: rectal temperature, heart rate, respiratory rate, pulse quality, and the presence of arrhythmia. Of the physical parameters, a rectal temperature below 95-96.6 degrees F (35-35.9 degrees C) or a heart rate below 120 b.p.m. were the most accurate predictors. When used in combination (i.e., evidence of bradycardia and hypothermia), the specificity for hyperkalemia was 98-100%.Conclusions: Rectal temperature and heart rate were the best parameters for predicting hyperkalemia in this population.