PLASMA VON-WILLEBRAND-FACTOR ANTIGEN CONCENTRATION IN DOGS WITH HYPOTHYROIDISM

Plasma von Willebrand factor antigen concentration was measured in 10 dogs with hypothyroidism, before and after administration of a replace ment dose of levothyroxine for 67 +/- 12 days. Results were reported a s a percentage of normal activity, with plasma pooled from clinically normal dogs given a value of 100%. Plasma von Willebrand factor antige n concentration was within reference limits in dogs with hypothyroidis m (126 +/- 41%) and was significantly (P < 0.01) decreased (94 +/- 39% ) after treatment with levothyroxine. Contrary to findings in some oth er studies, a deficiency of plasma von Willebrand factor did not appea r to result from hypothyroidism.