Abstract
BACKGROUND: Equine blood samples are often collected in uncontrolled, distant environments and stored for later analysis. AIMS: This study aimed to determine how sample storage methods influence complete blood count (CBC) parameters, hypothesizing that temperature and time elapsed from collection to analysis would affect CBC parameters. METHODS: Blood samples were collected from 10 healthy Quarter Horse mares (age: 13 ± 4.5 years old) and stored in EDTA tubes at room temperature (22°C), above ice (8°C), refrigerated (4°C), or in contact with ice (2°C). The IDEXX ProcyteDx was used to obtain CBCs at 3, 6, 12, 24, 48, and 72 hours after collection. Data were analyzed using the Kruskal-Wallis test with Dunn's post hoc analysis and Benjamini-Hochberg correction. Significance was set to P ≤ 0.05. RESULTS: A reduction of monocytes and elevation of basophils was seen as early as 48 hours at 2°C, 4°C, and 8°C and occurred to a greater extent at 22°C, likely due to a greater degree of cellular degradation. Changes to red blood cell parameters occurred as early as 48 hours after collection at 4°C and 8°C and were more exaggerated at 22°C. Storage at 2°C resulted in earlier differences in red blood cell parameters. In contrast with previous studies, platelet counts were increased with time in all cooled storage methods, exhibiting a progressive temperature-dependent response as early as 24 hours. CONCLUSION: It appears equine blood samples are most stable when stored at 4°C or 8°C and run within 48 hours when using the IDEXX Procyte Dx.