Plasma von Willebrand factor changes during various reproductive cycle stages in mixed-breed dogs with normal von Willebrand factor and in Doberman Pinschers with type-I von Willebrand's disease

Abstract

Objective - To determine whether plasma von Willebrand factor (vWf) concentration changes during the estrous cycle and pregnancy in Doberman Pinschers with type-I von Willebrand's disease (vWd) and in mixed-breed dogs with normal vWf, and if so, whether alterations in vWf concentration are associated with changes in serum concentrations of reproductive hormones. Animals - 5 sexually intact female Doberman Pinschers with type-I vWd and 8 sexually intact female mixed-breed dogs with normal vWf. Procedure - Concentrations of plasma vWf and serum progesterone and estradiol-17β were measured during the estrous cycle of nonpregnant dogs and during pregnancy, parturition, and lactation. Serum concentrations of total triiodothyronine, total thyroxin, and free thyroxin were measured during pregnancy, parturition, and lactation. Results - Von Willebrand factor concentration did not change during the estrous cycle, but during pregnancy, vWf concentration gradually increased. Peak concentrations were obtained at parturition and were 103 and 92% higher in mixed-breed dogs and dogs with type-I vWd, respectively, than were mean pre-pregnancy (anestrus) values. At parturition, total triiodothyronine concentration decreased from the pre-pregnancy value. The increase in vWf concentration during pregnancy was positively associated with changes in concentration of estradiol-17β and was negatively associated with changes in concentration of progesterone. Conclusions - The increase in vWf concentration in pregnant bitches may be associated with changes in concentrations of reproductive hormones. However, the increase in vWf concentration during pregnancy may involve other factors because vWf concentration did not change during the estrous cycle of nonpregnant dogs despite increases in concentrations of estradiol-17β and progesterone.