PLASMA VON-WILLEBRAND-FACTOR ANTIGEN CONCENTRATION AS A PREDICTOR OF VON-WILLEBRANDS-DISEASE STATUS IN GERMAN WIREHAIRED POINTERS

Objective-To evaluate the use of plasma von Willebrand's factor (vWF) concentration as a screening test for inherited von Willebrand's disea se (vWD) in German Wirehaired Pointers (GWHP). Design-Prospective stud y. Sample Population-Plasma samples from 467 GWHP. Procedure-Plasma VW F concentrations were measured as vWF antigen (vWF:Ag), using ELISA, a nd test values were used to estimate prevalence of vWD in GWHP and pre dict parental vWD status. Test results of progeny from matings of carr ier and noncarrier parents were then compared with the predicted outco me of such matings. Results-376 (81%) GWHP were classified as vWD nonc arriers, 58 (12%) as carriers, and 5 (1%) as affected with vWD. An add itional 28 (6%) GWHP could not be classified on the basis of plasma vW F:Ag concentration. The observed outcome of tests of 213 pups was not significantly different from that predicted on the basis of parental v WF:Ag concentration. The predictive value of a positive test result (V WF: Ag% < 50) for identifying vWD carriers was 0.89. Clinical Implicat ions-Plasma vWF:Ag concentration was an effective predictor of genetic status for the vWD trait, and for the outcome of matings between carr iers and noncarriers of vWD in this study of GWHP.