By Kim Rain
Published: 08/09/2023, edited: 08/10/2023
Reviewed by a licensed veterinary professional: Dr. Linda Simon, MVB MRCVS
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Vitamin K is a fat-soluble nutrient for dogs that is essential for the synthesis of coagulation proteins needed for blood to clot. Vitamin K1, or phylloquinone, is the primary dietary source of Vitamin K as it is synthesized in plants and can be consumed through food or supplements. Vitamin K2, or menaquinone, is synthesized by gut bacteria inside an animal’s body, and can also be found in some food sources. There is also a synthetic version of Vitamin K called Vitamin K3, or menadione.
In this guide, we’ll discuss why your dog needs Vitamin K, how much they should be consuming daily, and how to spot a deficiency of this much needed nutrient. But first, let’s take a look at the functions of Vitamin K for dogs.
While it may help to prevent heart disease and keep calcium from remaining in the arteries that can contribute to plaque, Vitamin K has one hugely important function that mammals simply can’t live without. This vitamin helps the blood to clot, a truly essential component of our bodies that allow us to recover from injuries. Without the ability to clot, blood would continue to flow out from wounds and injuries, making even minor ones fatal. But how does Vitamin K assist this important process?
Coagulation factors are proteins that are made in the liver. When a blood vessel or tissue injury occurs, these proteins work with the platelets in the blood to form a clot that stops bleeding. Four of the thirteen coagulation factors require Vitamin K during their creation to be able to function properly, and without it, blood simply won’t be able to clot.
Daily recommended intake
For most dogs, enough Vitamin K is produced internally by their own gut bacteria, which means they require very little in dietary sources. Some commercially made dog foods contain vitamin K along with other essential vitamins, but since this nutrient is synthesized by a dog’s own body, there aren’t any set recommended daily amounts.
However, there are conditions that may prevent vitamin K from being created, or compromise the amounts present in the body and may require supplementation. The National Research Council has recommended that puppies intake 0.33 mg of vitamin K for every 1,000 calories per cup (kcal), while adult dogs should consume 0.45 mg per 1,000 kcal.
As we mentioned above, a healthy dog will likely synthesize all the vitamin K they need in their gut, but there are safe dietary sources of vitamin K for dogs in case they need to consume more. Vitamin K1 is primarily found in leafy, green plants, while Vitamin K2 is in several animal products and fermented foods that contain probiotics. While safe for humans, not all of these foods are good choices to feed your dog.
Safe sources of Vitamin K1 for dogs include:
Safe sources of Vitamin K2 for dogs include:
- Hard and soft cheeses
- Pork chops
- Ground beef
- Beef, pork or chicken liver
Signs of vitamin K deficiency in dogs
A deficiency of vitamin K in dogs is rarely seen, as healthy animals will synthesize enough of this vitamin on their own. However, any dog can experience a condition that depletes this vitamin, or prevents it from synthesizing naturally, which in turn affects your dog’s blood clotting ability and can quickly become dangerous.
Ingestion of anticoagulant rodenticide, or simply mouse and rat poison, is the most common reason a dog can become deficient in vitamin K as the poison depletes the vitamin, which then directly affects blood coagulation. Too much vitamin E can also interfere with vitamin K’s role in blood clotting.
Your dog can also become deficient in this vitamin if they are unable to synthesize or absorb it due to altered gut bacteria, intestinal disease, intestinal malabsorption, antibiotic treatments, biliary obstruction, or intrahepatic cholestasis. A dietary lack of the vitamin can also occur in newborns.
Signs your dog is experiencing a Vitamin K deficiency can include:
- Excessive or prolonged bleeding from wounds, even if minor
- Spontaneous hematomas, or purplish bruises or swellings
- Pale or white gums
- Internal bleeding, observed outwardly as black or bloody diarrhea, coughing or vomiting blood
- Acute shock from blood loss
If your dog has eaten rodenticide, you may see these additional signs within 3 to 5 days of ingestion:
- Difficulty breathing
- Lameness or swollen joints
- Nose or gum bleeding
- Decreased appetite
- Bulging eyes
Treatment of Vitamin K deficiency
A vitamin K deficiency is generally treated with vitamin K supplementation therapy through injection, or more commonly in oral form. Supporting therapies are based on the cause of the deficiency and the dog's condition.
Signs of vitamin K overdose in dogs
Vitamin K for dogs is considered safe and has no known toxicity associated with high doses of it in its K1 or K2 forms. When ingested orally in the diet or as a supplement, vitamins K1 and K2 have shown no adverse side effects.
Some dogs can experience an allergic reaction when receiving vitamins K1 or K2 through injection. Administration of vitamin K1 this way has also been documented to cause bronchospasms and cardiac arrest, which is why oral forms of the vitamin are preferred by some.
However, the synthetic vitamin K3, or menadione, is known to be toxic and can cause an allergic reaction, hemolytic anemia, and liver cell damage. Since this form is banned for over-the-counter sales in the U.S., your dog likely won’t come into contact with it. Some pet foods do contain vitamin K3, so always look over the ingredients before feeding to your dog.
Signs of an overdose from Vitamin K3 include:
- Pale gums
- Yellowing eyes, skin or mucous membranes
- Breathing difficulties
- Decreased appetite
If you feel your dog is experiencing an allergic reaction or overdose from vitamin K, stop administering vitamin K and seek immediate medical attention from your veterinarian or emergency veterinary office.
Vitamin K supplements for dogs
While you can purchase vitamin K1 supplements for dogs, most dogs will synthesize enough vitamin K in their own bodies and will not need additional daily amounts. If your veterinarian feels your dog would benefit from additional vitamin K to ensure their blood can clot normally, supplements come in the form of chewable tablets, capsules or liquids that are easy to administer. Injections of vitamin K1 or K2 can also be given.
Your veterinarian may also prescribe Vitamin K for your dog to help reverse the effects of anticoagulant rodenticide poisoning, which is usually given as an antidote for several days. Vitamin K can be administered before surgery to ensure normal blood clotting in certain cases, such as with prolonged bleeding or bile duct issues. And in rare cases, vitamin K can be given to dogs with liver disease who are experiencing complications with prolonged bleeding.
Naturally occurring vitamin K is an essential nutrient your dog needs, but they are more likely to get enough through their own biological processes than through dietary food or supplements. Always speak with your veterinarian if you are considering giving your dog additional vitamin K, or if you feel they are experiencing a deficiency.
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