Vitamin K1 for Dogs: Uses in Rodenticide Poisoning

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Vitamin K1, also called phytonadione, is a prescription medication your vet may use when a dog has been exposed to an anticoagulant rodenticide. These poisons block the body's ability to recycle vitamin K, which is needed to make clotting factors II, VII, IX, and X. Without those clotting factors, a dog can develop dangerous internal bleeding.

Vitamin K1 does not neutralize every type of rat or mouse poison. It is used for anticoagulant products such as brodifacoum, bromadiolone, difethialone, diphacinone, and warfarin-type compounds. It does not treat bromethalin, cholecalciferol, or zinc phosphide poisoning, which is why identifying the exact product matters.

Your vet may start treatment with an injectable form in the hospital, then continue with oral tablets or capsules at home for several weeks. Oral doses are often given with food, especially a meal containing some fat, because that can improve absorption.

The most common use of vitamin K1 in dogs is treatment after confirmed or suspected ingestion of anticoagulant rodenticide. In many cases, dogs look normal at first. Bleeding signs often do not appear until the body's stored clotting factors are used up, which may take 2 to 5 days after exposure. Early treatment can make a major difference.

Your vet may also use vitamin K1 for other clotting problems linked to vitamin K deficiency or antagonism, though rodenticide exposure is the classic reason. Depending on your dog's condition, vitamin K1 may be only one part of care. Dogs that are already bleeding may also need bloodwork, oxygen support, plasma, or blood transfusions.

See your vet immediately if your dog may have eaten rat poison, even if there are no symptoms yet. Waiting for bruising, weakness, coughing, pale gums, nosebleeds, black stool, or collapse can allow a treatable exposure to become an emergency.

Vitamin K1 dosing is individualized by your vet based on the rodenticide involved, the amount eaten, your dog's weight, whether bleeding is already present, and follow-up clotting tests. Published veterinary references commonly describe an initial subcutaneous dose around 2.5 to 3 mg/kg, followed by oral dosing around 1.25 to 2.5 mg/kg every 12 hours for 14 to 28 days. Some references also note longer courses, often about 4 weeks, for second-generation anticoagulants such as brodifacoum.

The exact schedule matters. Stopping too early can allow bleeding to return after the medication is gone. That is why your vet may recommend a PT (prothrombin time) recheck 48 to 72 hours after the last dose before deciding treatment is complete.

Oral vitamin K1 is usually given with food, and a fat-containing meal may improve absorption. Do not substitute vitamin K3 or over-the-counter human supplements unless your vet specifically tells you to. Different products are not interchangeable, and the wrong form may not protect your dog.

Oral vitamin K1 is generally well tolerated in dogs. Mild stomach upset can happen, including decreased appetite, vomiting, or diarrhea. If your dog spits out doses or vomits soon after receiving one, contact your vet so they can advise whether the dose should be repeated.

Injectable vitamin K1 can cause pain, swelling, or tenderness at the injection site. Veterinary references caution against intravenous use unless a product is specifically labeled for that route, because serious anaphylactoid or allergic-type reactions have been reported with some formulations.

It is also important to separate medication side effects from signs of the poisoning itself. Weakness, pale gums, rapid breathing, coughing, bruising, bloody urine, black stool, or collapse are more concerning for ongoing bleeding than for vitamin K1 intolerance. Those signs need urgent veterinary care.

Vitamin K1 is often used specifically because another substance has interfered with normal clotting. The biggest concern is not a classic drug interaction list, but the full medication picture around a dog that may already be at risk for bleeding. Tell your vet about all prescriptions, flea and tick products, supplements, herbal products, and any possible toxin exposures.

Dogs recovering from anticoagulant rodenticide exposure may need extra caution with medications that can increase bleeding risk or complicate monitoring, such as NSAIDs, aspirin, clopidogrel, or other anticoagulant or antiplatelet drugs if your dog is already taking them for another condition. Your vet may also want to know about liver disease, malabsorption problems, or vomiting that could affect how well oral vitamin K1 is absorbed.

Do not start, stop, or swap medications on your own during treatment. If your dog misses doses, vomits medication, or needs another drug while taking vitamin K1, your vet can help adjust the plan safely.