Breed Dependency of Reference Intervals for Plasma Biochemical Values in Cats

Background: Reference intervals (RI) are pivotal in clinical pathology. The influence of breed on RI has been poorly documented in cats. Hypothesis/Objectives: RI for plasma biochemistry variables are breed‐dependent in cats. Animals: Five hundred and thirty‐six clinically healthy, fasted, client‐owned cats from 4 breeds: Holly Birman (n = 132), Chartreux (n = 129), Maine Coon (n = 139), and Persian (n = 136). Methods: Prospective observational study: Blood samples were collected from the cephalic vein into capillary tubes containing lithium heparin. Plasma glucose, urea, creatinine, total proteins, albumin, calcium, phosphate, sodium, potassium, chloride, and total CO₂ concentrations and the activities of alanine aminotransferase and alkaline phosphatase were assayed with a dry slide biochemical analyzer. RI were defined as central 95% intervals bounded by the 2.5th and 97.5th percentiles. Data were analyzed by a linear mixed effects model with type I error rate of 0.05. Results: A significant (P < .05) breed effect was observed for 9/13 variables. The magnitude of the differences between breeds could be clinically relevant for creatinine, glucose, and total protein. Age, body weight, sex, and housing conditions had significant (P < .05) breed‐related effects on different variables. Conclusions and Clinical Importance: Breed‐specific RI should be considered for cats.