Studies on platelet aggregation using the Born method in normal and uraemic dogs
ABSTRACT Using the Born method, based on light transmission in platelet rich plasma, the minimum effective concentration (threshold values) of several platelet agonists for inducing maximum platelet aggregation was determined in healthy dogs. The final concentrations of aggregation agonists were as follows: adenosine diphosphate (ADP) (0.5-50 micromol/L; n = 75 healthy dogs), collagen (0.5-20 mg/mL; n = 75), thrombin (0.1-5 IU/mL; n = 75), ristocetin (1-10 mg/mL; n = 10), and epinephrine (5-50 micromol/L; n = 10). Reference values for maximum aggregation with a lower limit of > 80% were achieved for agonist concentrations 25 micromol/L ADP (80-98%), > or = 10 microg/mL collagen (80-96%), and > or = 1 IU/mL thrombin (80-97%). None of the concentrations of epinephrine and ristocetin used in this study induced quantitative aggregation in the whole group of healthy dogs. We also studied platelet aggregation in 14 uraemic dogs using selected concentrations of aggregation agonists. Aggregation was significantly decreased in uraemic dogs using intermediate agonist concentrations, i.e., in the region of the threshold concentration. In contrast, maximum aggregation was increased in uraemic patients compared to reference values using low concentrations of all three agonists (ADP: 1 micromol/L, collagen: 1 microg/mL, and thrombin: 0.1, 0.2 IU/mL).
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- "The turbidimetric method used in the present study has greater clinical relevance and it is easier to standardize than the electrical impedance method. Other agonists can be used, such as ristocetin and epinephrine, but dogs platelets are much less responsive to these substances than human platelets; therefore, ADP is the first choice agonist for platelet aggregation test in dogs . "
ABSTRACT: Thrombosis has been associated to some diseases like hyperadrenocorticism (HAC). Several drugs can alter the balance, such as the corticosteroid prednisone, used mainly for its anti-inflammatory and immunosuppressive effects. It is known that hypercortisolism can stimulate thrombi formation by increasing coagulation factors and decreasing fibrinolysis. However it is not known how prednisone administration affects hemostasis in dogs and if it is dose dependent. The aim of this study, therefore, was to demonstrate the effects of prednisone administration on dogs' hemostatic profile. Significant decrease of antithrombin levels was observed in both groups (anti-inflammatory and immunosuppressive doses) after 15 days of treatment. An increase of platelet aggregation was observed in dogs receiving immunosuppressive doses of prednisone (Group II). From the results obtained in our study, it is not possible to infer that hypercortisolism can increase the thromboembolic risk, despite the decreased anticoagulant factors (antithrombin levels).BMC Veterinary Research 12/2013; 9(1):268. DOI:10.1186/1746-6148-9-268 · 1.78 Impact Factor
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ABSTRACT: Im Rahmen dieser Dissertationsarbeit sollte festgestellt werden, ob die Vollblutaggregometrie mittels eines Hämatologiesystems eine praxisrelevante Möglichkeit zur Feststellung der Thrombozytenfunktion (insbesondere Thrombozytopathien) beim Hund darstellt. Das Standardverfahren die Aggregometrie nach BORN erfordert eine schnelle Probenverarbeitung und ist aufgrund der hohen Gerätekosten für den Einsatz in der Praxis häufig nicht zugänglich. Als weiterer Nachteil dieser Methode ist das größere Probenvolumen zur Gewinnung von plättchenreichem Plasma (PRP) und die mögliche Aktivierung der Thrombozyten durch die Probenverarbeitung zu sehen. Im Gegensatz dazu stellt die Vollblutaggregometrie eine Möglichkeit dar, die Funktion der Thrombozyten bei Erkrankungen und zur Therapiekontrolle auch unter Praxisbedingungen zu überprüfen. The goal of this study was to evaluate whether whole blood aggregometry performed by routine haematology analysers is a valuable tool to assess canine thrombocyte function (especially thrombocytopathia) in routine veterinary practice. The reference method (BORN aggregometry) necessitates fast sample processing and is relatively impractical due to high costs. An additional disadvantage of this method is the large sample volume needed to create platelet-rich plasma (PRP) and the possibility of premature activation of platelets due to sample handling. In contrary, whole blood aggregometry seems to be a method that facilitates assessment of platelet function in a clinical setting.
Chapter: Hemostasis[Show abstract] [Hide abstract]
ABSTRACT: This chapter reviews the comparative biochemistry of hemostasis. Hemostasis, the process of arresting the escape of blood from the vascular system, is integral to survival in animals. Hemostasis is regulated by a series of orchestrated events, and is dependent on the vessels through which blood flows, as well as numerous proteins and cells. Other systems in the body, such as the innate immune system and the inflammatory response, are also closely related to blood clotting and are influenced by the activation of hemostasis. The stepwise process that takes place to minimize blood loss and repair the injury includes initial vasospasm; platelet activation and plug formation; assembly and activation of the coagulation cascade factors; fibrin clot formation at the site of injury; and dissolution of the clot and vascular repair. This chapter begins with discussing the mechanisms of hemostasis and then elaborates laboratory assessment of hemostasis, as well as disorders of hemostasis. The chapter also describes how the dramatic variations in blood clotting in different species impact laboratory testing, response to therapeutic agents, downstream effects on other body systems, and the array of diseases that can occur.Clinical Biochemistry of Domestic Animals, 01/2008: pages 287-330; , ISBN: 9780123704917