Is Too Much Vitamin D Bad for Dogs?

Is Too Much Vitamin D Bad for Dogs?

Posted by volhard dog nutrition on Oct 12th 2023

Yes, elevated levels of vitamin D are dangerous for dogs.

Vitamin D finds its place among other fat-soluble vitamins, such as A, E, and K, which are stored in the fat and liver of the dog's body. The more of this fat-soluble vitamin the body stores, the higher the chances of poisoning in dogs.

Furthermore, vitamin D toxicity can lead to high calcium levels in your dog's blood (hypercalcemia), harming their bones and critical internal organs like the heart, kidneys, and stomach.

Dogs typically exhibit symptoms of Vitamin D poisoning 12 to 24 hours after ingestion and require the help of veterinary professionals for complete recovery.

How Do Dogs Get Their Vitamin D?

Vitamin D for dogs

Dogs cannot synthesize vitamin D the way humans do.

The mere mention of "vitamin D" evokes images of sunbathing at the beach on a warm, sunny day.

However, no amount of sunshine will help your furry friend get their share of this vital nutrient.

That's one of the reasons why 75% of dogs need vitamin D supplements in their diet. (Source: Dogs Naturally)

The 2 Types of Vitamin D

Vitamin D falls into two categories:

  • D2 (Ergocalciferol), which comes from plant sources.
  • D3 (Cholecalciferol), the most usable form, comes mainly from fatty meats and liver.

Once your dog consumes vitamin D3 through their food, the body starts metabolizing it into a usable form.

Vitamin D3 is first absorbed through the intestines, then it's converted by the liver into 25-hydroxy vitamin D or Calcifediol.

From there, the kidneys convert it into the 1,25-Dihydroxyvitamin D Serum.

That is when the parathyroid glands rely on this usable form of vitamin D to absorb bone calcium absorption and regulate blood pressure and blood sugar levels.

How Does Vitamin D Benefit Your Dog's Health?

First and foremost, vitamin D helps your dog's body absorb essential minerals, mainly calcium and phosphorus—key minerals to maintaining strong bones and teeth. Without enough vitamin D, your dog's bones may become weak or brittle.

Second, vitamin D supports numerous body parts by strengthening the immune system, as well as the spleen, liver, and intestines.

Another significant role of vitamin D is its contribution to cancer protection.

Lastly, vitamin D is linked to maintaining healthy blood pressure and blood sugar levels. It ensures the kidneys function correctly, filtering out waste and keeping the body balanced.

4 Causes of Elevated Vitamin D Levels in Dogs

  1. Elevated Levels of Vitamin D in Pet Food: Numerous commercial pet foods were recalled by the FDA due to toxic levels of vitamin D causing illnesses or death in dogs. Examples of recalled products include Hill's Science Diet, Hill's Prescription Diet, and Purina's Pro Plan Veterinary Diets EL Elemental (PPVD EL). (Source: FDA)
  2. Accidental Consumption of Vitamin D Supplements: Any open container of vitamin D supplements within your dog's reach is a sign of trouble.
  3. Cholecalciferol Rodenticides: Accidentally eating rat and mouse poison will increase your dog's vitamin D3 levels, potentially leading to toxicity. (Source: FDA)
  4. Skin Cream Ingestion: Various skincare medications (for example, topical psoriasis) contain high levels of vitamin D. Ensure that you safely store the containers and that your dog doesn't lick the cream off your skin. (Source: VCA)

7 Clinical Signs of Vitamin D Poisoning in Dogs

7 signs of vitamin D poisoning in dogs

The Dangers of Vitamin D Toxicity for Dogs

The main concern with having too much vitamin D is a condition known as hypercalcemia—the presence of too much calcium in the blood.

While calcium helps build strong bones and teeth, having too much of it in the bloodstream can be problematic. The body starts depositing excess calcium in various parts, such as the heart, blood vessels, and especially the kidneys, affecting their function.

The most severe consequence of hypercalcemia due to vitamin D toxicity is kidney failure. The kidneys are responsible for filtering waste out of the blood. When they get clogged up with excess calcium, they stop performing their job properly, putting your dog's life in danger.

The Dangers of Not Getting Enough Vitamin D

One of the primary roles of vitamin D is to help the body absorb calcium and phosphorus—two minerals crucial for bone health. Without enough vitamin D, a dog's bones can become weak and brittle. This condition, called rickets in puppies, may cause their legs to bow out. A lack of this nutrient in older dogs leads to osteomalacia, making their bones soft and more likely to break.

Besides bone issues, vitamin D deficiencies weaken your dog's muscles and nerves, slowing their movement. Dogs might also lose their appetite and end up losing weight.

Furthermore, vitamin D plays a role in supporting the immune system. Without enough of it, dogs could become more susceptible to infections and illnesses.

Not All Dogs Process Synthetic Vitamin D

Some dogs face challenges processing synthetic vitamin D versions often found in commercial dog food. If your dog can't absorb it, it's as if the vitamin isn't there at all! This can lead to a vitamin D deficiency even though the food label suggests they're getting plenty.

The source and quality of vitamin D in dog food are vital. Just having it listed as an ingredient isn't enough. The key is its "bioavailability," which means how well a dog's body can take in and use the vitamin.

If the vitamin D isn't bioavailable, it won't benefit the dog, no matter how much of it is in the food. So, it's crucial for dog owners to be aware of the type of vitamin D found in dog food and to understand that synthetic versions are not the best choice for their four-legged partners.

Vitamin D absorption in dogs

Other factors known to decrease vitamin D absorption include:

  • Polyunsaturated Fats
  • Tap Water: It lowers your dog's magnesium levels, an essential cofactor for vitamin D.
  • Strong Magnetic Fields
  • Exposure to Polychlorinated Biphenyls or PCBs: They increase the risk of deficiency by 3%.
  • Glyphosate: A potent chemical found in popular herbicides such as Roundup.
  • Spaying/Neutering: Research shows that spayed females have 9% less 25-hydroxy vitamin D than intact ones, and neutered males have 27% less than intact ones. (Source: Dr. Judy Morgan's Naturally Healthy Pets)

How to Diagnose Vitamin D Poisoning in Dogs

How to diagnose vitamin D poisoning in dogs

Diagnosing vitamin D poisoning in dogs involves a combination of observing the symptoms, understanding the dog's recent medical history, and conducting specific medical tests:

  • Clinical History: The vet will inquire about the dog's recent activities, diet, and any exposure to foods and substances containing vitamin D to identify the source(s) of poisoning.
  • Physical Examination: A thorough check-up will provide clues, especially if your dog shows symptoms consistent with vitamin D poisoning.
  • Blood Tests: They are vital in diagnosing vitamin D poisoning. Elevated calcium and phosphorus levels in the blood may indicate excess vitamin D ingestion. The vet might also look for elevated kidney values.
  • Urine Test: It helps determine your dog's kidney function levels. Their kidneys might not concentrate urine as effectively in cases of vitamin D poisoning.
  • X-Rays: If there's a concern about your dog ingesting rat and mouse poison, X-rays will show any undigested pellets.

Vitamin D Toxicity Treatment

The treatment approach toward vitamin D poisoning often depends on its severity and how quickly it's caught.

If the dog has recently consumed a product with high amounts of vitamin D and it's brought to the vet's attention promptly, the vet might induce vomiting to get it out of the dog's system before absorption.

Sometimes, the vet might give your dog activated charcoal to prevent the toxin from getting into the bloodstream.

Blood tests play a vital role in both diagnosing and treating vitamin D poisoning. Through these tests, your vet monitors calcium levels and other indicators in the blood to see how the dog responds to treatment.

In cases where the poisoning has affected the dog's internal organs, particularly the kidneys, the vet may provide intravenous (IV) fluids to flush out the calcium from the bloodstream, reducing the strain on the kidneys.

Changing your dog's diet is another essential step toward recovery. Since vitamin D poisoning leads to high calcium levels in the blood, you need to put the dog on a special low-calcium diet.

The Role of Vitamin D Testing in Preventing Toxicity

Testing for Vitamin D levels helps pet parents understand if their dogs have the right amount of this nutrient in their system. From our experience, VDI Laboratories, LLC provides an excellent test that tells you how much vitamin D you need to supplement. It's reasonably affordable and gives you a holistic panel of your dog's nutrient levels and their relationship with your dog's health.

Proactiveness is the Fastest Avenue Toward Vitamin D Poisoning Prevention

Dogs do not have the luxury of vitamin D absorption through their skin, and their bodies will tell us when they get too much or too little of this nutrient. Make sure to keep a close eye on the causes and signs of vitamin D toxicity and implement a consistent plan for prevention. For more advice on dog nutrition, health, and training, make sure that you contact us and check out our blog!

Volhard Dog Nutrition and its expert nutritionists are now offering online consultations to help more dog parents discover why, what, and how to feed their dogs the healthiest of foods! Speaking to a Volhard nutritionist will help you understand the inseparable relationship between healthy food, a healthy body, and a healthy mind. If you're interested in contacting one of our Volhard nutritionists, don't hesitate to access our consultation page!

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