Vitamin K is a fat-soluble vitamin necessary for normal blood coagulation and control of calcium deposits in bones and tissues. This vitamin is required for healthy blood function in all animals, including our pets. Vitamin K1, also known as phytonadione, is the dietary form of vitamin K found in plants and most food supplements. Another form of vitamin K such as vitamin K2, is naturally synthesized in the intestinal tract, while vitamin K3 is lab-developed. Vitamin K1 can be used for your dog in a few circumstances, specifically if they have ingested certain poisons. 

Why is Vitamin K1 Used in Dogs? 

Between the foods we eat and the natural vitamins in the stomach, there’s a healthy supply of vitamin K, so there is little need for food supplements. However, a lack of vitamin K can cause blood hemolysis and anemia. So why vitamin K1 for dogs?  

How or why would your dog ingest an anticoagulant poison? Surprisingly, this happens often. Long-acting anticoagulants, LAACs, are common poisons formulated for rats and mice. They kill rodents by preventing their blood from clotting, causing internal bleeding. Should your dog mistakenly ingest a poison of this type, vitamin K1 is the only antidote. 

How Effective is Vitamin K1 for Dogs? 

Rat poisons contain potent anticoagulants called superwarfarins. These compounds work similarly to blood thinner medication that stops blood clots in heart patients. The difference is that these compounds are long-acting and may continuously thin the blood for over three to five days, eventually leading to death. Vitamin K1, a natural blood coagulant, works by reversing the anticoagulant effect of rodenticides. Superwarfarins remain in the body for a prolonged time and it takes approximately 30 days of continuous vitamin K1 for dogs to be considered safe. There are barely any reports of vitamin K1 overdose, but its synthetic counterpart, vitamin K3, can cause an overdose. 

Symptoms of Rodenticide Poisoning 

Because of their action mechanism, outward signs of poisoning are not typically seen for up to 5-7 days after ingestion. At this time, bleeding may be too excessive for the pet to survive. However, if your dog has been exposed to a large dose, symptoms may come sooner. These symptoms may include: 

  • Bloody stools 
  • Difficulty breathing 
  • Weakness 
  • Coughing 
  • Vomiting 
  • Pale gums 
  • Lethargy 
  • Depression 
  • Collapse 

Without prompt treatment, your pet will be fatally affected. 

Treatment of Rodenticide Poisoning 

Timely intervention is required if your dog ingests an anticoagulant rodenticide. Your veterinarian needs time to induce vomiting and eliminate the poison while administering vitamin K1. Activated charcoal will also be prescribed to stop further absorption of the poison. However, if your dog has ingested the poison over 24 hours beforehand, decontamination therapy measures may not be as effective and vitamin K1 alone may be started.  The form of vitamin K1 needed to treat anticoagulant rodenticide poisoning can NOT be purchased over the counter and is only available through your veterinarian or pharmacy with a prescription. Supportive care may include intravenous fluids or blood transfusion to stop hemorrhaging. If your pet has consumed an anticoagulant rat poison, contact your vet and Pet Poison Helpline® at (855) 764-7661 right away for life-saving assistance.