Ionized calcium concentrations in cats with septic peritonitis: 55 cases (1990-2008).

OBJECTIVE: To report the prevalence of ionized hypocalcemia (iHCa) in cats with septic peritonitis, and to determine whether hypocalcemic cats had increased morbidity and mortality when compared with normocalcemic cats. DESIGN: Retrospective clinical study. SETTING: University teaching hospital. ANIMALS: Fifty-five client-owned cats with septic peritonitis. MEASUREMENTS: Medical records of 55 cats with confirmed septic peritonitis meeting the study inclusion criteria were reviewed. Information obtained included signalment, cause of peritonitis, length of hospitalization (LOH), length of ICU stay, and outcome. Results from serum biochemical analysis, blood gas analysis, and coagulation testing from the time of diagnosis, and all ionized calcium (iCa) measurements during hospitalization were recorded. Systolic blood pressure, the presence of arrhythmias and administration of vasopressor agents, blood products, and sodium bicarbonate were documented. iCa concentration at the time of diagnosis and lowest recorded value during hospitalization were compared with LOH and length of ICU stay, survival to hospital discharge, and clinical and clinicopathologic data. MAIN RESULTS: iHCa (iCa<1.20 mmol/L) was found in 89% of cats (49/55) at the time of diagnosis of septic peritonitis and 93% (51/55) at any time during hospitalization. There was no association between the presence or severity of iHCa at diagnosis and survival to hospital discharge. LOH (P=0.046) and duration of ICU stay (P=0.026) were significantly correlated with the lowest iCa recorded during hospitalization. Failure to normalize iCa during hospitalization was associated with a decreased survival rate to discharge (P=0.029) in patients with iHCa. iHCa was not associated with an increased prevalence of hypotension, coagulopathy, arrhythmias, or evaluated therapies. CONCLUSIONS: iHCa is more prevalent in cats with septic peritonitis than described previously. Failure of iCa to normalize during hospitalization may be a negative prognostic indicator. iHCa may be predictive of a longer LOH and ICU stay, but is not necessarily associated with a poorer prognosis.