RESUMO
OBJECTIVE: To establish reference values for activated coagulation time (ACT) in normal cats and dogs, by visual assessment of clot formation using the MAX-ACT(TM) tube. SUBJECTS: We recruited 43 cats and 50 dogs for the study; 11 cats and 4 dogs were excluded from the statistical analysis because of abnormalities on clinical examination or laboratory testing including anaemia, prolonged prothrombin time (PT) or activated partial thromboplastin time (APTT), or insufficient plasma volume for comprehensive laboratory coagulation testing. PROCEDURE: Blood samples were collected via direct venipuncture for MAX-ACT, packed cell volume/total solids, manual platelet estimation and PT/APTT measurement. Blood (0.5 mL) was mixed gently in the MAX-ACT tube at 37 degrees C for 30 s, then assessed for clot formation every 5 to 10 s by tipping the tube gently on its side and monitoring for magnet movement. The endpoint was defined as the magnet lodging in the clot. The technique was tested with 10 dogs by collecting two blood samples from the same needle insertion and running a MAX-ACT on each simultaneously. RESULTS: In normal cats the mean MAX-ACT was 66 s (range 55-85 s). In normal dogs the mean was 71 s (range 55-80 s). There was no statistical difference between the first and second samples collected from the same needle insertion. CONCLUSIONS: and Clinical Relevance In both cats and dogs, a MAX-ACT result >85 s should be considered abnormal and further coagulation testing should be performed. Additionally, failure to discard the first few drops of the sample does not appear to significantly affect results.
