Objective— To report the prevalence of hypophosphatemia after renal transplantation in a historical cohort of cats.

Design— Case series.

Animals— Cats (n=86) that received a renal allograft.

Methods— Medical records (January 200–June 2006) were reviewed. Signalment, clinical signs, pre- and postoperative diet, pre- and postoperative clinicopathologic variables, renal histopathology, and outcome were retrieved. Prevalence, onset, duration, treatment and associated clinical signs of hypophosphatemia were recorded. A χ2 test was used to compare hemolysis frequency between cats with normal serum phosphorus concentration or a single spurious low serum phosphorus concentration for <24 hours duration (group 1) and confirmed hypophosphatemia for >24 hours (group 2). A Cox proportional hazards model was used to evaluate the effects of hypophosphatemia on survival while controlling for other potentially confounding variables (age, sex, weight, body condition score, and pre- and 24 hours postoperative clinicopathologic variables).

Results— Eighty-six cats (mean age, 7.7 years) were identified. Hypophosphatemia occurred in 32 cats (37%), with a median onset of 2 days and median duration of 4 days. Treatment was initiated in 48 (56%) of hypophosphatemic cats. Survival and hemolysis frequency was not significantly different between groups, and no risk factors were identified.

Conclusion— Hypophosphatemia occurs in cats after renal transplantation and does not affect survival.

Clinical Relevance— The clinical importance of hypophosphatemia in renal transplant recipients remains unknown.