Pharmacological therapy for hyperkalemia in feline urethral obstruction has no additional benefit over intravenous fluid and calcium gluconate therapy and prompt unobstruction.

OBJECTIVE

Urethral obstruction (UO) in male cats is a potentially fatal condition due to hyperkalemia. The objective of this study was to compare the effect of IV fluids and calcium gluconate (IVF-Cg) alone or with insulin/dextrose, terbutaline, or sodium bicarbonate on hyperkalemia in male cats presenting with UO.

METHODS

Male cats presenting to a university hospital with UO and a blood potassium > 7.5 mEq/L were prospectively enrolled in this experimental study from July 2019 to September 2024. All cats received a fluid bolus and calcium gluconate dose IV. Cats were randomized to receive IVF-Cg alone or with terbutaline, insulin-dextrose, or sodium bicarbonate. The relative reduction in blood potassium after 4 hours was compared between groups.

RESULTS

The study enrolled 34 cats, with 8 cats in the bicarbonate and insulin/dextrose groups and 9 cats in the IVF-Cg and terbutaline groups. The median baseline and 4-hour potassium for all cats was 9.1 mEq/L (range, 7.5 to 11.8 mEq/L) and 5.4 mEq/L (range, 4 to 8 mEq/L) respectively. The median relative reduction in blood potassium was 29% (6% to 50%) for IVF-Cg, 37% (12% to 55%) for insulin-dextrose, 36% (8% to 45%) for sodium bicarbonate, and 52% (10% to 56%) for terbutaline. There was no significant difference in percentage change in potassium between groups.

CONCLUSIONS

There is no significant difference between the various treatments for hyperkalemia in male cats with UO.

CLINICAL RELEVANCE: There is no adjunctive therapy that is clearly beneficial for promoting resolution of hyperkalemia. Prompt relief of obstruction, calcium gluconate, and administration of IV fluids result in rapid reduction of hyperkalemia and a good prognosis.