Evaluation of time and temperature storage in platelet counts in blood samples of dogs

The reliability of platelet counts obtained by different methods following different storage times/conditions is not well defined. The aim was to evaluate temporal changes in platelet count of canine blood samples submitted to two thermal storage conditions using three techniques of platelet counting. Blood samples were obtained from 40 dogs aged between 6 months and 12 years. Blood samples were collected by jugular venipuncture, separated into two aliquots, and stored in EDTA tubes: one kept at room temperature (RT group) and the other kept under refrigeration (RE group). The platelet count was performed using the hemocytometer method, blood smear counting, and automated counting immediately after blood collection (M0) and 30 min and 1, 2, 4, 6, and 24 h later in both groups. The platelet parameters provided by the electronic counter were also obtained. There was a significant difference in platelet counts between the manual and automated methods when the samples were processed 24 h after sample collection. The refrigerated samples remained with closer platelet values of the previous samples for longer than those stored at room temperature. The analysis of platelet parameters loses its validity when the samples are stored for more than 6 h. The plaquetogram is reliable when the sample is processed up to 4 h after collection, regardless of the storage method. The timing of the platelet count should not exceed 6 h after collection for refrigerated samples and 4 h for samples stored at room temperature, for all counting methods.