A 1.5-year-old female Bichon Frise dog was evaluated for a life-threatening hemorrhagic condition that occurred after ovariohysterectomy, requiring 4 whole-
blood transfusions. A
hemostatic profile, including activated clotting time (ACT), one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), buccal mucosal bleeding time, and specific assays (heat-precipitation microhematocrit method and electroimmunoassay) for
fibrinogen, were performed to investigate the coagulopathy. Clotting times for all tests having a
fibrin clot endpoint (ACT, OSPT, APTT) and buccal mucosal bleeding time were prolonged. Plasma
fibrinogen was not detected by heat-precipitation microhematocrit method or electroimmunoassay. Using the Ellis-Stransky method, a mixture of patient plasma and normal canine plasma with known
fibrinogen content yielded substantially less than the calculated
fibrinogen concentration, indicating the presence of an interfering substance. The interferent properties of the patient's plasma were retained following heat precipitation at 56 degrees C indicating the absence of a pyroglobulin or an abnormal
fibrinogen molecule. Radial immunodiffusion assay using the patient's plasma and activated
thrombin confirmed the existence of an inhibitor to the formation of
fibrin. Western blot analysis using the patient's plasma identified an
IgG antibody that reacted with the Beta- and gamma- but not the Alpha-subunits of canine
fibrinogen. Antibody was detected in samples taken 8, 16, and 68 days after the surgery; peak titers were evident at day 16. These results supported a diagnosis of
afibrinogenemia with a circulating antibody inhibitor to
fibrin clot formation that developed secondary to
blood transfusion.