Stability of Cerebrospinal Fluid Proteins in Dogs and Cats: Effects of Refrigeration and Freezing Over Time

ABSTRACT Background The quantification of protein levels is an important part of standard cerebrospinal fluid (CSF) analysis. However, delays in processing due to shipment and/or laboratory opening schedules, combined with the need to preserve sample stability during storage, pose critical challenges to ensuring accurate diagnoses. Objectives Our aim was to assess the stability of CSF proteins in canine and feline samples refrigerated and subsequently frozen. Methods CSF samples were prospectively collected from dogs and cats. CSF protein levels were measured: immediately after collection; after refrigeration (at 4°C for 48 h); and after freezing (at −20°C for 6 to 150 days). Linear regression was performed for each species to evaluate the influence of time and preservation on protein levels. The impact of the variation in CSF protein measurements on clinical interpretation was evaluated. Results Fourteen dogs and four cats with neurological diseases, and five cats euthanized for reasons unrelated to neurological issues were enrolled in the study. Protein measurements were stable over time in dogs ( p = 0.334) and cats ( p = 0.785), regardless of the preservation method and timing of analysis. The variation between the CSF protein measurements of fresh and stored samples did not change the interpretation of any results. Conclusions CSF protein levels in dogs and cats remained stable when samples were refrigerated for 48 h prior to being frozen for long‐term storage, supporting the feasibility of banking samples for research and laboratory control. Additional studies are necessary to evaluate the stability of specific protein biomarkers.