ObjectivesThis exploratory study aimed to evaluate the methaemoglobin fraction in cats with sepsis, non-septic sick counterparts and healthy controls, and to assess the feasibility of using the methaemoglobin fraction as a biomarker for predicting clinically relevant outcomes such as duration of hospitalisation and mortality.MethodsMedical records were retrospectively searched for all cases of confirmed sepsis presenting to the ICU of two referral hospitals, from September 2016 to January 2019 in Institution A and March 2019 and October 2024 in Institution B, with a methaemoglobin measurement taken on admission. Records were also searched for cats presenting to the ICU of Institution B from March 2019 to October 2024 who met 2/4 SIRS criteria without evidence of infection. The methaemoglobin levels of these cases and those of previously collected data from healthy cats (from both institutions) were compared to those of the septic population. Data from each institution was analysed separately.ResultsA total of 47 cats with sepsis were enrolled (23 in Institute A and 24 in Institute B), as well as 100 NSS cats from Institute B and 53 healthy controls (42 in Institute A and 11 in Institute B). Data from each Institute was analysed separately. The median methaemoglobin fraction was significantly higher in control cats compared to septic cats in institution A (1.7%, 0.1-2.6% vs 1.1%, 0.1-6.9%, P = 0.03). There was no significant difference in methaemoglobin levels between combined septic survivors vs non-survivors (0.5%, 0.2-6.9% vs 0.9%, 0.1-3.6%, P = 0.5).Conclusions and relevanceThis exploratory study was unable to demonstrate a significantly increased circulating methaemoglobin fraction in cats with sepsis or an association between methaemoglobin fraction and survival outcome. These findings support the feasibility of further research and highlight the need for adequately powered standardised multicentre studies to clarify the biomarker's clinical utility.
McGuigan et al. (Tue,) studied this question.