Blood preservative solutions allow erythrocyte storage and facilitate the work of blood banks and immediate access in cases of emergency transfusions. Cellular changes occur during blood storage and it can affect red blood cells (RBC) functionality and contribute to decrease in cellular viability after transfusion. Blood collection for transfusion purposes in cats have complications due to the small volume that can safely be withdraw and the lack of a method to facilitate the collection and allow storage of blood for a longer period. Many clinicians still use heparinized blood collected into syringes to immediate transfusion procedures in cats, since blood bags design for smaller volumes are not commercially available in many countries. ACD-A is a preservative solution used in apheresis procedures in humans and animals. The hematological and biochemical parameters of feline blood stored in ACD-A glass tubes were evaluated to determine its viability and quality in vitro for possible future studies in vivo. Blood samples were obtained from 10 cats clinically healthy, through jugular vein puncture, using 8.5 mL tubes containing 1.5 mL of ACD-A (BD-Vacutainer®, São Paulo, Brazil). Samples were stored for five weeks between 1-6°C. On days 1, 7, 14, 21, 28 and 35 after collection, stored blood aliquots were withdraw for evaluation of hemoglobin (Hb), sodium, potassium, P50, pO₂, pCO₂, pH, chloride, glucose, lactate, plasma hemoglobin and packed red cells volume (PCV). During storage, glucose level decreased significantly probably due to the RBC metabolism with consequent lactate formation and reduction of pH values, raising P50 and pO₂ levels (p < 0.05). There was no significant decrease in PCV values and hemolysis degree didn't exceed the limits of 1.0% total hemoglobin. Chloride ion had variations below reference values and it could be explained by the ion dilution and displacement into RBC's. Sodium and potassium values increased significantly (p < 0.05), possibly due to the increase in plasmatic membrane permeability during storage. Results indicate viability of feline blood storage in ACD-A solution for five weeks in vitro, whereas evaluated metabolites remained within the range required for blood transfusion. The advantages of this method is the smaller quantity of blood collected, reaching also feline donors with lower body weight, and the fact of being a closed system, reducing the possibility of blood contamination during storage. However, it should be considered a way to transfuse the blood from the glass tubes to the receptor without the air contact and the consequent formation of bubbles.