Evaluation of blood thiamine concentration in hospitalized dogs with and without critical illness.

Objective: To evaluate blood thiamine concentration in healthy and critically ill hospitalized dogs over 72 hours of hospitalization and to identify any association of thiamine concentration with patient morbidity and mortality.

Design: Prospective, observational, clinical study.

Setting: University veterinary teaching hospital.

Animals: Thirty-one hospitalized healthy dogs and 37 dogs with critical illness. Dogs with critical illness had nonseptic (n = 24) or septic (n = 13) etiologies.

Interventions: None.

Measurements And Main Results: Whole blood EDTA samples were collected within 24 hours of admission and 72 hours later. Samples were stored at -80°C and batch analyzed. Total thiamine (tB1) and thiamine diphosphate (TDP) concentrations were measured using high-performance liquid chromatography, and free thiamine concentration was determined using liquid chromatography with tandem mass spectrometry. Collected patient data included CBC, biochemistry profile, plasma lactate concentration, shock index, Acute Patient Physiologic and Laboratory Evaluation Score (APPLE ) score, comorbid conditions, and patient outcome. Approximately 92% of tB1 present in whole blood is measured as TDP. TDP concentration was strongly correlated with tB1 (R = 0.97, P < 0.0001). Thiamine concentration, represented by TDP, was not different at admission or at 72 hours in all dogs. TDP concentration was lower in septic dogs requiring surgery at admission (P = 0.044) and 72 hours later (P = 0.008), compared to dogs not requiring surgery. TDP concentration was not different between dogs with and without stable chronic diseases at any time point. Older dogs had lower TDP concentration. Positive correlations were seen between TDP and body weight, APPLE score, and WBC count. Critically ill dogs with lower admission plasma lactate concentration were more likely to have an increase in thiamine over time (P = 0.0142).

Conclusions: Differences in thiamine concentration were not identified in hospitalized healthy or critically ill dogs. Further investigation into the clinical relevance of thiamine deficiency is indicated in septic dogs undergoing surgery.