Evaluation of a Prothrombin Time Optimized for the Dog on Plasmas with Defined Coagulation Factor Deficiency Due to Coumarin Intoxication

Abstract

Summary The sensitivity of the standard prothrombin time (PT) was low when measured on 56 plasmas with a reduced activity of the coagulation factors mainly of the prothrombin complex (factors II, VII and/or X) taken from eight dogs at different times of vitamin therapy after coumarin intoxication. This was demonstrable by use of three different Ca‐thromboplastins. With the standard test only plasmas with an excessive decrease of coagulation factor activity (sum of activity decrease of the single factors in relation to the respective reference range [SAD >100 %) were detectable with sufficient reliability. In contrast, by using a method optimized for dogs (1:20 sample predilution, fibrinogen substitution) and respecting the species specific features of coagulation physiology, pathological PT‐values were measured in up to 70 % of the samples (dependent on the Ca‐thromboplastin) with slight reductions of single factor activity (SAD: 11–25 %). Significant differences concerning the sensitivity were seen additionally between the different Ca‐thromboplastins. Human placenta thromboplastin in particular, but also rabbit brain thromboplastin, were more sensitive than a preparation of recombinant human tissue factor. The correlation between the PT and the SAD was closer when using the optimized method (r = 0.919–0.954) compared to the standard test (r = 0.771–0.862). In contrast to the standard test, the PT optimized for dogs is, therefore, a reliable screening test to recognize a slight reduction in prothrombin complex. It is especially suitable for monitoring of vitamin K1 therapy after coumarin intoxication.

Effects of preoperative administration of carprofen on renal function and hemostasis in dogs undergoing surgery for fracture repair

“…The APTT is a commonly used screening test for evaluating the endogenous coagulation system of dogs and humans, 28 whereas PT is used as a global screening test for evaluating the extrinsic coagulation system for diagnosis and follow-up evaluation of coagulopathies caused by vitamin K deficiency, hepatopathy, and disseminated intravascular coagulation. 29 However, PT and APTT do not predict the amount or complexity of hemostatic alterations. 50 Measurement of concentrations of fibrin degradation products, fibrinogen, or antithrombin III would have yielded more information about the ongoing hemostatic alterations.…”

“…l Hematologic variables-Platelet count and Hct were determined by use of an automated hematologic analyzer. m The APTT and PT were measured as described elsewhere 28,29 by use of a semiautomatic crochet coagulometer n and standard clinicopathologic techniques. To measure APTT, 100 µL of PPP was incubated with 100 µL of APTT reagent o (diluted with diethylbarbiturate acetate buffer p ) at 37 o C for 2 minutes.…”

Evaluation of secondary haemostasis in canine leishmaniasis

“…The extrinsic and common pathways were evaluated by measurements of the modified one‐stage prothrombin time (m‐OSPT) (Neoplastin plus; Boehringer Mannheim) which was determined according to the technique described by Mischke (1995). The intrinsic and common pathways were assessed by measurements of the activated partial thromboplastin time (APTT) (Pathromtin; Behring) (Greene and Beck 1980) with kaolin as the activator reagent.…”

Vergiftung mit Cumarinderivaten beim Hund: Retrospektive Analyse klinischer und labordiagnostischer Daten

“…Letzteres wurde durch Zentrifugation (10 min bei 2500 x g oder 2 min bei 10 000 x g) von mit Natriumcitrat antikoaguliertem Blut (1 Teil 0,11 mol/l Natriumcitrat und 9 Teile Blut; Probengefäße von Sarstedt, Nümbrecht) gewonnen. Zur Bestimmung der modifizierten Prothrombinzeit, die eine zuverlässigere Detektion von Gerinnungsfaktormängeln des extrinsischen und gemeinsamen Aktivierungsweges beim Hund ermöglicht [33], wurde zunächst das Citratplasma mittels eines Imidazol-Puffers (Siemens Healthcare) im Verhältnis 1:20 verdünnt. 100 μl von diesem Citrat-Plasma-Puffer-Gemisch wurden mit ebenfalls 100 μl einer Lösung von Humanfibrinogen (Haemochrom Diagnostika, Essen) in isotoner Kochsalzlösung (2 g/l) für 2 min bei 37 °C inkubiert.…”

“…Ein direkter Vergleich wird durch unterschiedliche Messmethoden mit variierenden Empfindlichkeiten der Tests limitiert. Dies betrifft insbesondere die bei den eigenen Fällen erfolgte Messung der Prothrombinzeit mit einer für den Hund optimierten Methodik, deren Ergebnis analog zum Quick-Wert des Menschen in einer abweichenden, standardisierten Form als Prozent Aktivität der Norm angegeben wird [33].…”