Open AccessProthrombin, Activated Partial Thromboplastin, and Proteins Induced by Vitamin K Absence or Antagonists Clotting Times in 20 Hyperthyroid Cats Before and After Methimazole Treatment
Author(s) -
Randolph John F.,
DeMarco JoAnn,
Center Sharon A.,
Kantrowitz Lawrence,
Crawford Mary Ann,
Scarlett Janet M.,
Brooks Marjory
Publication year - 2000
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/j.1939-1676.2000.tb01500.x
Subject(s) - partial thromboplastin time , medicine , cats , prothrombin time , clotting time , methimazole , clotting factor , thromboplastin , coagulation , gastroenterology , endocrinology , thyroid
The effect of daily doses of 5–15 mg of methimazole on the platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), and proteins induced by vitamin K absence or antagonists (PIVKA) clotting time in 20 hyperthyroid cats was determined. No significant ( P > .05) difference was found in median platelet count, PT, APTT, or PIVKA clotting time before treatment compared to median values at 2–6 weeks or ≥7–12 weeks of methimazole treatment. No cat had a prolonged APTT at any time. At 2–6 weeks of methimazole treatment, 1 cat each developed thrombocytopenia or prolonged PIVKA clotting time despite initially normal values. Three cats had abnormal coagulation tests (prolonged PT [n = 1] and PIVKA clotting time [n = 3]) before treatment that fluctuated during treatment. Excluding the 3 cats that had abnormal PIVKA clotting time before treatment, prolonged PIVKA clotting time developed in 6% (1/17; 95% confidence interval, 0–28%) cats treated with methimazole for 2–6 weeks. Seemingly, doses of methimazole commonly used to treat hyperthyroidism in cats do not cause alteration in PT and APTT, and only rarely prolong PIVKA clotting time. Nevertheless, abnormal PIVKA clotting time may explain bleeding tendencies unassociated with thrombocytopenia in methimazole‐treated hyperthyroid cats.