Vitamin K Deficiency

Introduction

The absolute or relative deficiency of vitamin K can give rise to defective coagulation. Anticoagulant rodenticide toxiticy is one of the most common causes of acquired coagulopathy in small animals. Warfarin itself has a short half-life and a fairly low toxicity in non-rodent species, so unless large or repeated doses are consumed clinical bleeding is rare. However, the second generation anticoagulant rodenticides are far more potent, and it is possible for a domestic animal to acquire secondary poisoning by ingesting a killed rodent¹. Dogs are most commonly effected, but predator species such as cats and owls do occaionally suffer from secondary poisonings.

The clotting factors - factor VII, factor XI and factors II and X in the extrinsic, intrinsic and common pathways respectively are dependent on Vitamn K when activated by the coagulation cascade.

Other Causes of Vitamin K deficiencies

Malabsorption syndromes and sterilisation of the gastrointestinal tract by prolonged antibiotic usage will also result in the depletion of vitamin K-dependent clotting factors². In herbivores, fungi growing on poorly prepared hay or silage containing sweet vernal grass or sweet clover may break down natural coumarins in the plants to form dicoumarol and cause poisoning.

A whole blood or plasma tranfusion immediately provides vitamin K dependent clotting factors, The specific treatment of anticoagulant rodenticide toxicosis is administration of vitamin K₁.

References

Also see Anticoagulant Rodenticide Toxicity