A crude, whole-body extract of female heartworms was administered IV to 10 dogs with and 13 dogs without heartworm (HW) infection. Shock developed in 8 of 10 infected dogs and 11 of 13 non-infected dogs, and blood coagulopathy was observed in 12 of 19 dogs with shock. Prevalence and severity of blood coagulopathy were proportionate to prevalence and severity of shock. Platelet count decreased in all dogs with shock with or without blood coagulopathy; thus, the decrease in platelet count might be related to shock. In 4 dogs, activated partial thromboplastin time (APTT) was prolonged--192.0 seconds at 30 minutes after HW injection--and prothrombin time (PT) was increased--13.8 seconds at initial collapse. In 8 dogs, APTT was increased--200 seconds for 2 hours after HW injection--and PT was increased--200 seconds at 30 minutes after the injection. The APTT prolongation might have been caused mainly by decreases in activities of factors VIII, IX, XI, and XII of the intrinsic blood coagulation pathway. In dogs with severely prolonged PT, plasma fibrinogen concentration and factor II activity decreased slightly. Prolonged PT was corrected in vitro by addition of normal plasma at high concentration (> 80%), but prolonged APTT could not be corrected in vitro by addition of 80% normal plasma. Serum fibrin degradation products concentration was < 10 microgram/ml, and soluble fibrin monomer complex was negative in all dogs. Thrombi were not found in blood vessels of any organ at necropsy and after histologic study. Therefore, it was suggested that blood coagulopathy resulting from inhibition of coagulation factor activities might develop in shock induced by HW extract.

Immunochemical methods that are used to assess von Willebrand factor in human beings and dogs were used to assess von Willebrand factor in 3 cat species. Our findings indicated that the expression and multimeric composition of von Willebrand factor in plasma and platelets of cats were similar to those reported in human beings and dogs. We suggest that these methods may be used to evaluate von Willebrand disease in members of the cat family used in this study.

acute Sarcocystis cruzi infection in calves (exper.), hematologic studies support claim that anemia is an extravascular hemolytic event, probably with immunologic basis; coagulation studies indicate that endothelial S. cruzi schizonts may cause endothelial damage, resulting in coagulation abnormalities that include disseminated intravascular coagulation

The purpose of this study was to evaluate a commercial enzyme-linked immunosorbent assay (ELISA) for human von Willebrand factor antigen (vWF:Ag) with respect to its potential value in quantitating the protein in canine plasma. The assay was a sandwich technique using F(ab')2 fragments specific for von Willebrand factor (vWF) and a peroxidase conjugated rabbit anti-vWF second antibody, with a microplate as the support surface. Canine plasmas were assayed by ELISA, and by Laurell electroimmunoassay (EIA), our reference methodology. The ELISA had a within-day variation of 1.21-4.44% and a between-day variation of 0.85-4.88% depending on the level of vWF:AG. The sensitivity of the assay was less than 0.1% vWF:AG. The range of vWF:AG concentrations in plasmas from 24 clinically normal dogs compared favorably with the range for the same plasmas when assayed by EIA (ELISA = 60-152% of normal; EIA = 50-142% of normal). In 121 canine plasmas with vWF:AG concentrations (as assessed by EIA) ranging from undetectable levels (< 6% of normal) to 142% of normal, there was good correlation with measurements made by ELISA (correlation coefficient = 0.835). It was concluded that this commercial ELISA technique could be used to provide reliable, same-day measurements of canine plasma vWF:AG. Since it requires no special equipment other than a microplate reader and washer it is particularly suitable for laboratories lacking the electrophoretic expertise or equipment required for EIA.

We determined whether administration of cryoprecipitate or fresh-frozen plasma (FFP) would enhance glass bead platelet retention and shorten the bleeding time in von Willebrand factor (vWf)-deficient Doberman Pinschers. Plasma concentration of vWf was < 15% of the reference value in these dogs and, on the basis of multimeric analysis of vWf, these dogs had type-I von Willebrand's disease (vWd). Concentration of vwf in cryoprecipitate (prepared from FFP of clinically normal dogs) was enriched almost 20 times, and the preparation was a concentrate of the largest and most physiologically active multimers. Administration of a dose of cryoprecipitate calculated to increase plasma vWf concentration of recipient dogs to 50 U/dl increased plasma vWf concentration in recipient dogs to about 40 U/dl. Mean buccal mucosal bleeding time (BMBT) shortened from 6.7 minutes before treatment to 3.8 minutes at 2 hours after treatment. Cryoprecipitate from donor dogs treated with deamino-8-D-arginine vasopressin (1 microgram/kg of body weight) effectively shortened mean BMBT from 6.4 minutes to 3.1 minutes. Administration of cryoprecipitate from vWf-deficient dogs prolonged, rather than shortened, the BMBT. After FFP (450 ml) infusion, plasma vwf concentration increased in recipient dogs, but the BMBT did not shorten. Glass bead platelet retention did not change after administration of cryoprecipitate or FFP. Thus, cryoprecipitate, especially from deamino-8-d-arginine vasopressin-treated donor dogs, is a concentrate of the most hemostatically active multimers of vWf and decreases the BMBT in dogs with vWd.