Antivitamin K (AVK) toxicity is a common problem in companion animal medicine. The vitamin K-dependant coagulation factors II, VII, IX and X are altered by AVK, inducing clotting disorders. Main clinical symptoms are cough, lameness, hematoma, hematuria, melena. Increased One Stage Prothrombin Time (OSPT) and Activated Partial Thromboplastin Time (APTT) are main biological alterations, but these modifications are not pathognomonic.
In France, emergency treatment consists in intravenous injection of vitamin K1 (Vitamin K1 injectable TVM®). Contrary to other formulations, this product doesn't contain cremophor as excipient, and injection-associated shock is exceptional.
We studied effects of IV administration of vitamin K1 (5 mg/kg) on OSPT and APTT kinetics during AVK intoxication and others clotting disorders (i.e., DIC, ophidian envenomation, angiostrongyliasis, Von Willebrand disease, hepatopathy...). We used an in-house analyzer (SCA 2000, Idexx laboratories), with fresh blood samples collected from jugular vein.
We observed a rapid return to normal value, within 20 minutes after injection of vitamin K1, of OSPT and APTT in all suspected AVK intoxications in dogs (n=78) and cats (n=31). On the other hand, we didn't observe any significant influence of vitamin K injection on OSPT and APTT in other coagulation disorders (45 dogs and 18 cats).
With this simple test, veterinary practitioners can now confirm a diagnosis of AVK intoxication in 20 minutes.