False thrombocytopenia may result from platelet aggregation, especially in feline ethylenediamine tetra-acetic acid (EDTA) blood specimens. Citrate, theophylline, adenosine and dipyridamole (CTAD) was added to 46 feline EDTA specimens to test its anti-aggregation action. Platelet aggregation was estimated from blood films and a complete blood count was performed with a Sysmex XT-2000iV analyser. Platelet aggregation score was >2 in 11/46 EDTA tubes and only in one EDTA+CTAD specimen. The platelet count was higher in all CTAD-supplemented tubes except one, medians measured by cytometry being 225.5 × 10(9)/l and 249.0 × 10(9)/l in EDTA and EDTA+CTAD, respectively (P = 0.007). Adding CTAD had statistically and analytically significant but moderate effects on other blood variables, the most intense variations being observed for reticulocytes (about 3% higher in EDTA specimens) and reticulocyte indexes. Addition of CTAD to EDTA when sampling feline blood is a useful option to reduce platelet clumping.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

The generic canine RIs established in the same laboratory with analogous preanalytical and analytical variations did not differ significantly from breed-specific RIs, and thus have no significant impact on clinical decision making; however, breed-specific RIs are advised for some RBC and all platelet-related variables to avoid erroneous suspicion of polycythemia and thrombocytopenia when using general canine RIs for evaluation of DDB.

Objectives Universal anticoagulant could be an alternative to the multiple blood sampling required for clinical pathology investigations in cats. An association of citrate, theophylline, adenosine and dipyridamole (CTAD) has been reported to be a good substitute for EDTA for haematology analysis in cats, limiting platelet clumping, and has also been shown to be valid for haematology, secondary haemostasis and some biochemical variables in humans. The aim of the study was therefore to investigate the effects of CTAD on in vitro platelet aggregation and compare results of secondary haemostasis and biochemistry tests, excluding a priori those variables not reliably measured in CTAD, such as sodium, chloride and divalent cations, in feline blood specimens collected in CTAD and paired citrate and heparin tubes. Methods Thirty blood specimens sampled in citrate and CTAD were analysed for in vitro platelet aggregation, and 60 blood specimens sampled in citrate or heparin and CTAD were analysed for plasma coagulation and a biochemistry panel. Results In vitro platelet aggregation was inhibited in CTAD compared with citrate specimens. Prothrombin time, activated partial thromboplastin time, antithrombin and fibrinogen results were similar, despite some significant differences. Measurements of triglycerides, cholesterol, glucose, urea, creatinine, phosphate, total proteins and alanine aminotransferase activity were similar and well correlated in CTAD and heparin plasmas, despite some significant differences and moderate biases. Albumin showed a marked positive proportional bias, and creatine kinase and alkaline phosphatase activities a moderate and marked negative mixed bias, respectively, but could be measured in CTAD if new reference intervals were calculated. Aspartate aminotransferase activity showed a marked negative proportional bias, along with a poor correlation and some clinical misclassifications just like the potassium concentration, and thus cannot be recommended to be measured in CTAD specimens. Conclusions and relevance In cats, CTAD cannot be used for primary haemostasis investigation but could be a suitable (almost) universal anticoagulant for routine haematology, as well as for plasma coagulation and many biochemistry variables.