The Role of Vitamin D in Dogs: Importance for Bone and Muscle Health

May 10, 2024

Just like it is in humans, Vitamin D is vital for dogs because it helps maintain strong bones and healthy muscles. It manages the levels of calcium and phosphorus in the body, which are essential for developing and maintaining bone strength. But while it’s important, it’s also important you know how to make sure your dog’s getting enough Vitamin D, and be super careful that they’re not getting too much.

Research has shown that vitamin D is beneficial for dogs, especially after they’ve been injured. It helps reduce oxidative stress, which happens when there are too many free radicals and not enough antioxidants in their body. Vitamin D boosts antioxidant levels, which protects the muscles from damage. Additionally, it supports the health of their mitochondria, which are tiny structures in their cells that produce energy. Mitochondria are essential for muscle function and repair in dogs.

Vitamin D is essential because it helps your dog’s body absorb calcium, which is necessary for strong bone formation. This is particularly important in preventing conditions like osteomalacia in adult dogs and rickets in puppies, which can cause bones to become soft and weak. Additionally, vitamin D helps improve muscle strength, which can protect bones by decreasing the likelihood of falls and related injuries​​ from running and jumping.

Symptoms of Vitamin D Deficiency in Dogs

If your dog is suffering from Vitamin D deficiency, you may see several different symptoms. They include:

  1. Weakness and Lethargy: Dogs with a Vitamin D deficiency may be tired and less enthusiastic about activities they normally enjoy. They might struggle to keep up on walks or not want to play with you when they normally would.
  2. Muscle Atrophy: This is the wasting or thinning of muscle tissue, which can occur because vitamin D is crucial for muscle maintenance and function. A deficiency can lead to a noticeable decrease in muscle mass, making dogs appear weaker and less sturdy.
  3. Bone Pain: Just like in humans, a lack of vitamin D in dogs can cause their bones to weaken, which can be painful. Dogs are so good at hiding discomfort, so this may not be super obvious at first, but signs can include a reluctance to jump or climb stairs and a general decrease in activity.
  4. Limping or Difficulty in Moving: This can be a direct result of the bone pain or general weakness that insufficient vitamin D causes and may be more noticeable after resting or during colder weather when symptoms of joint issues can worsen.

Sources of Vitamin D for Dogs

Dogs get the bulk of their Vitamin D from their diets. Unlike humans, their skin doesn’t allow them to synthesize Vitamin D from the sun as well. That’s not to say they aren’t able to at all, it’s just their diet is the main source of Vitamin D for them. That’s why it’s so important to be sure they’re getting enough healthy, holistic nutrients. Some of the major dietary sources of Vitamin D for dogs include the following:

  1. Fish: Fatty fishes like salmon, mackerel, and sardines are excellent sources of Vitamin D and provide significant amounts in a natural form that’s easy for dogs to absorb.
  2. Beef Liver: This is another rich source of Vitamin D, packed with other beneficial nutrients as well, making it a good option for boosting Vitamin D levels in dogs.
  3. Egg Yolks: They contain Vitamin D in smaller amounts compared to fish and liver, but they can still contribute to the overall dietary intake of this essential nutrient.

A word about fortified dog foods: Commercial dog foods are designed to meet AAFCO guidelines and basic requirements. Many are fortified with Vitamin D to make sure there’s an adequate amount in their day-to-day meals, but it’s also something to be intentional about when looking at ingredients so there’s no excess Vitamin D as that can lead to toxicity.

And, while sunlight does contribute to Vitamin D synthesis in dogs, the amount synthesized is so minimal. Dietary sources and supplements are crucial for maintaining optimal health.

Risks of Vitamin D Excess in Dogs: A Holistic ViewpointPhoto: A Yorkie eats a Vitamin D pill for bone health.

Vitamin D toxicity, also known as hypervitaminosis D, can pose significant risks to dogs if not managed properly. Vitamin D toxicity in dogs can occur when they consume too much of it in their diet, which is often due to excessive amounts added to commercial pet foods. This can lead to dangerously high levels of calcium and phosphorus in the body, resulting in the calcification of tissues such as the kidneys, gastrointestinal tract, heart, and arteries. This calcification can cause severe health issues, including kidney failure, which can develop rapidly if the vitamin D levels are excessively high.

Symptoms of Vitamin D toxicity in dogs include vomiting, weakness, frequent urination, excessive thirst, and in severe cases, weight loss and lethargy. As symptoms progress, they may lead to more severe complications such as renal failure.

Treatment should start by immediately stopping the intake of Vitamin D for your dog. Your veterinarian will look at blood results to assess levels and treatment may even include fluid therapy to support kidney function and medications to manage symptoms. From a holistic perspective, ensuring a balanced diet that offers Vitamin D in credible, clean, and trusted ways is the best avenue for preventing Vitamin D overdose in dogs.

Regular checks to monitor Vitamin D levels can also help prevent toxicity. Making sure your dog has natural sources of Vitamin D balanced with other nutrients can help maintain health without the risk of overdose.


At Bernie’s Best, we’re dedicated to offering the best for your dog’s health. While Vitamin D plays a vital role in bone health, we believe comprehensive joint care is crucial. Bernie’s Marvelous Mobility is what we designed to go beyond basic support by including premium, science-backed ingredients like Omega-3 fatty acids, turmeric, and green-lipped mussels. These are known for their powerful anti-inflammatory and joint-supportive properties. We purposely chose them over other popular ingredients because we wanted research-based efficacy. We designed Marvelous Mobility to help you give your dog excellent joint health and mobility every day. We’re all about quality of life and longevity, and Marvelous Mobility is an excellent and delicious way to make sure your dog’s days are pain-free and full of life! 

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