The diagnostic test panel to evaluate coagulation in large animals can include platelet count, plasma Semiquantitative fibrinogen to assess for increased fibrinogen concentra­tion, prothrombin time (PT), partial thromboplastin time (PTT),

and serum fibrin and fibrinogen degradation products (FDPs). Alternatively, thromboelastography (TEG) may be substituted for (or performed in addition to) the combination of PT, PTT, and FDPs.

Proper collection and preparation of blood samples are paramount in obtaining accurate results (see Chapter 23). Platelet counts are routinely performed as part of the complete blood cell count (CBC). Citrated blood is required for coagulation testing including PT, PTT, FDPs, and TEG, and can also be used for platelet analysis including platelet count. It is critical to have a 1 : 9 ratio of citrate to whole blood. The patient's hematocrit can affect coagulation results when whole blood is used. When the hematocrit is more than 55%, correction to a lower citrate volume is recommended to prevent overcitration and prolonged coagulation times.¹ If the laboratory does not have reference intervals for a particular species, plasma from two or more healthy animals should be collected and assayed in a similar manner for comparison. Table 27.1 shows reference values for platelets and fibrinogen, but laboratory-specific values are preferable for these analytes and are necessary for other coagulation parameters.

More on the topic The diagnostic test panel to evaluate coagulation in large animals can include platelet count, plasma Semiquantitative fibrinogen to assess for increased fibrinogen concentra­tion, prothrombin time (PT), partial thromboplastin time (PTT),: