Laboratory evaluation and interpretation of haemostasis in small animals

Abstract

This review deals with indications for performing haemostasis tests, methodical aspects of blood sampling and handling of sample material, selection of appropriate tests and basic principles of test interpretation. Indications for laboratory evaluation of haemostasis in small animals include spontaneous bleeding or bleeding disproportionate to the degree of trauma, bleeding from multiple sites and diseases which are frequently associated with haemostatic disorders. Patient history and clinical findings can deliver clues for the type of haemorrhagic diathesis. Important preanalytical issues include prevention of prolonged venous stasis, order of drawing and appropriate filling of the collection tubes and careful mixing of blood with anticoagulant. Initial screening can be performed by global tests of haemostasis including viscoelastic testing using thrombelastography and rotation thrombelastometry and/or a "basic examination profile" including platelet count, capillary bleeding time (optional in cases of suspected functional platelet disorders) and group tests prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin (clotting) time (optionally in cases of prolonged PT and APTT). This procedure allows a rational evaluation of the haemostatic system and a specific use of further tests including individual coagulation factor activities, inhibitor activities, activation markers, examination of von Willebrand factor, and platelet function analyses. It is important (1) to use species-and method specific reference values for interpretation and (2) to consider the limitations of tests when performed according to the standard test procedure optimised for human sample material (e.g., low sensitivity of PT test for canine and feline samples).

Coagulation profile in two nephropathic dogs

“…dysfunction. Compared to the acute renal injury, CBT, PT, aPTT, D-Dimer concentration were more elevated in the chronic kidney disease of this study.The prolonged CBT observed in both these cases might be due to thrombocytopaenia or platelet dysfunction (Mischke, 2014). In acute kidney injury, severe thrombocytopenia with normal PT, aPTT indicated the absence of consumption of clotting factors.…”

Koagulacijske pretrage u veterinarskoj medicini

“…Također, neprimjeren je i uzorak kojem je vrijednost hematokrita za 10 % veća od njegove gornje referentne vrijednosti iako je volumen krvi u spremniku odgovarajući. Naime, zbog povećanog hematokrita, udio plazme je manji pa je stoga omjer plazme i antikoagulansa promijenjen (Miloš, 2010., Funk i sur., 2012., Mischke, 2017. ).…”

“…Osim urođenog, detektira se i stečeni nedostatak faktora vanjskog puta kao posljedica otrovanja (mišomor), uporabe određenih lijekova (antagonisti vitamina K), bolesti jetre ili diseminirane intravaskularne koagulacije (DIK). Zbog praćenja faktora II, VII i X koji su ovisni o vitaminu K, pretraga je i konvencionalni test za utvrđivanje statusa vitamina K. U slučajevima nedostatka vitamina K, faktori koji o njemu ovise nisu funkcionalni, njihova aktivnost je smanjena te je vrijeme zgrušavanja produženo, odnosno vrijednosti PV-a su veće od referentnih (Brooks i Catalfamo, 2013., Mischke, 2017. ).…”