Vitamin D for Dogs: Effects, Dosage, and Natural Sources

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Vitamin D is a fat-soluble vitamin necessary for the proper absorption of calcium and phosphorus in the body. Like humans, canines also need this vitamin to have strong bones and healthy nerves and muscles. Our pets obtain theirs from sun exposure but their bodies don’t produce it in their skin the same way we do. Instead, they rely on their fur for Vitamin D.

Since our pets only consume it by licking or grooming their coat, it means they get an insignificant amount of Vitamin D from UVB rays. We eventually need to provide our dogs with Vitamin D-rich foods to meet their nutritional requirements. Is it safe to give some Vitamin D to our furry little friends? Read on to find out.

What You Need to Know About Vitamin D

Vitamin D comes in two major forms, Vitamin D2 or ergocalciferol and Vitamin D3 or cholecalciferol. Vitamin D2 can be derived from plants while D3 comes from animal sources. In humans, D3 is normally obtained when our bare skin is exposed to sunlight.

It matters to maintain a healthy balance of both forms. Excessive amounts of any of the two may come with a few risks. Too much Vitamin D3, for instance, has been linked to hypercalcemia or the abnormally high amount of calcium in the blood. Excessive D2, on the other hand, may cause frequent urination, behavioral changes, and shortness of breath.

Vitamin D is fat-soluble which means any excess of it in the body goes through the liver. This is the reason why cod liver oil, an excellent source of Vitamin D, is not always recommended for canines. There are actually conflicting opinions regarding the use of cod liver oil for dogs.

Some owners give it to their pets suffering from arthritis. On the other hand, there are those who believe it could do more harm than good to their pets. A canine with kidney or liver problems should not take cod liver oil.

How Much Vitamin D Does a Dog Need?

According to the Association of American Feed Control Officials, dogs should have around 500 IU of Vitamin D for every kilogram of dog food. In the form of supplements, it should not be more than 100-120 ng/ml of Vitamin D per day.

Like many of us, almost all domesticated dogs these days don’t have a lot of time outdoors. This means the main source of Vitamin D3 for them only comes from foods. It’s risky to give Vitamin D to dogs without your vet’s consent. The only way to find out if your dog needs a supplement is by having him examined. Your vet should perform a blood test to determine if the vitamin levels in the blood are low.

It’s important to be aware of the proper dosage because Vitamin D can be poisonous to dogs if ingested in unrestricted quantities. The signs to keep an eye out for with Vitamin D poisoning are too much drooling, pain in the stomach, vomiting, inappetence, sudden loss of weight, and lethargy.

If you suspect your dog ingested more Vitamin D than he should have, call an animal poison control center or better bring him to the nearest veterinary hospital.

What Are the Benefits of Vitamin D to Canines?

  • It can prevent heart diseases such as congestive heart failure. Vitamin D is important for healthy muscles and there is no more important muscular organ in the body than the heart. Without enough of this nutrient, your pet could suffer from complications associated with heart disease.
  • It can lower cancer risks in dogs. Several pieces of research suggest that there are inadequate levels of Vitamin D among cancer-bearing patients. Even in humans, several studies are linking Vitamin D deficiency to cancer and mortality.
  • It is used as a treatment for hyperparathyroidism caused by kidney disease in dogs. If your pet is experiencing such a condition, your veterinarian will likely prescribe active Vitamin D or calcitriol along with a modified diet.
  • It can be used as a treatment for rachitic dogs. A study published in the Journal of Animal Research in 2017 suggested that Vitamin D3 along with Calcium can correct clinical signs of rickets in dogs after an 8-week treatment. A canine with rickets either lacks the nutrient or inefficiently reacts to it.

What Are the Natural Sources of Vitamin D?

Humans get Vitamin D from a wide range of foods. For our pets, we have to be extra careful especially if they have sensitive stomachs. Some Vitamin D-rich sources, such as cheese, cereal, and fortified milk, can make a lactose intolerant dog sick. If your pooch is quite sensitive to dairy, here are the safest ones you can offer to your pet:

  • Meat – the liver part of cooked beef comes with 15 IUs for every 3-ounce serving. Meat, in general, comes with naturally occurring Vitamin D3. Meat is also a great source of high-quality protein for dogs. Serve it to your pet with vegetables, eggs, or grains.
  • Fish – cooked salmon is an excellent source of Vitamin D for dogs. A 3-ounce serving already provides 360 IUs. Other fatty fishes such as mackerel, sardines, and tuna also have high amounts of it.
  • Eggs – the yolk is abundant in Vitamin D. A piece can already give your dog 20 IUs of Vitamin D. As long as your pet does not have digestive problems eating eggs, you can safely give it to them twice to thrice a week.
  • Squash – cook the squash and give it as it is. You can also incorporate it into your pet’s home cooked meals. Your pet will surely enjoy the taste of butternut squash because of its sweetness.
  • Oatmeal – if your pooch is quite sensitive to wheat and grains, you can give him oats or oatmeal as a substitute. Look for oatmeal that is already fortified with Vitamin D because regular oat may only have very little amounts of it.
  • Mushrooms – unless it’s wild mushrooms, then there’s nothing to worry about giving a few pieces to Fido. Store-bought mushrooms are definitely safe to eat. You may also use them for making medicinal broth for your pet. Shiitake is the best type to use because it has antibacterial and antiviral properties. A small shiitake mushroom provides 7 IU of Vitamin D.

The Bottom Line

Vitamin D is one of the important nutrients for dogs. Without enough Vitamin D, their ability to absorb calcium and phosphorus is reduced. Your pet’s best sources of this nutrient come from food. If you’re planning to make some changes to your pet’s diet, consult your veterinarian first. Choose natural food sources over commercial dog food as the latter may contain synthetic Vitamin D. There’s no need to give it in the form of supplements because too much of it can harm your pet’s liver in the long run. In fact, it can be toxic in large amounts.


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