Vitamin D

What is vitamin D?

Vitamin D is not actually a true vitamin, but a group of fat-soluble hormones that are formed from cholesterol. The most important forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is mainly found in plant foods, while vitamin D3 is produced in animal foods and through the effect of sunlight on the skin.

Vitamin D is converted into its active form, known as calcitriol, in the liver and kidneys. Calcitriol regulates the calcium and phosphate balance in the body and promotes the absorption of these minerals from the intestine. It also influences the formation and breakdown of bone cells, muscle contraction, nerve conduction, cell division and immune defense.

How much vitamin D does your dog need?

The optimal amount of vitamin D for dogs is not exactly known as it depends on many factors, such as age, weight, health, breed and diet. In general, however, dogs have a higher need for vitamin D than humans, as they cannot produce it as well through the skin.

The National Research Council (NRC) recommends a daily intake of 10 micrograms (µg) of vitamin D per kilogram of body weight for adult dogs. For puppies and pregnant or lactating bitches, the requirement is 25 µg per kilogram of body weight. These values are considered the minimum to avoid a deficiency. However, some experts believe that dogs need more vitamin D to stay healthy.

How can you provide your dog with vitamin D?

The best source of vitamin D for dogs is a balanced diet that includes both plant and animal foods. Fish oil, cod liver oil, egg yolk, dairy products and some mushrooms are particularly rich in vitamin D. Some ready-made foods also contain added vitamin D, but you should always pay attention to the quality and dosage.

Another way to provide your dog with vitamin D is through sun exposure. However, this is only effective to a limited extent, as the coat and pigmentation of the skin inhibit the formation of vitamin D3. In addition, too much sun can also be harmful and lead to skin cancer or sunburn. You should therefore not expose your dog to direct sunlight for too long and always provide sufficient shade.

What are the benefits of vitamin D for dogs?

Vitamin D has many positive effects on your dog's health. Some of them are:

• It strengthens bones and teeth by promoting the storage of calcium and phosphorus. This is especially important for growing puppies and older dogs with osteoporosis.
• It supports muscle function by improving contractility. This can increase your dog's performance and balance.
• It protects the nervous system by promoting the formation of myelin. This is an insulating layer around the nerve fibers that speeds up signal transmission. This can improve your dog's learning ability and memory.
• It strengthens the immune system by activating defense cells and regulating the inflammatory response. This can protect your dog from infections and autoimmune diseases.

What are the disadvantages of vitamin D for dogs?

Although vitamin D is vital for dogs, it is not without danger. Too much vitamin D can lead to an overdose, known as hypervitaminosis D. This can have serious consequences for your dog's health. Some of these are:

• It increases calcium and phosphorus levels in the blood, which can lead to calcification of soft tissues such as the kidneys, heart, lungs and blood vessels. This can impair the function of these organs and lead to heart failure or kidney failure.
• It causes nausea, vomiting, diarrhea, loss of appetite, weight loss and weakness. This can lead to dehydration and malnutrition.
• It disrupts hormone balance by inhibiting the production of parathyroid hormone. This is a hormone that keeps the calcium and phosphorus balance in equilibrium. This can lead to an imbalance of these minerals and result in bone loss or muscle cramps.

How do you recognize a vitamin D deficiency or overdose in your dog?

A vitamin D deficiency or overdose in your dog is not always easy to recognize, as the symptoms are often unspecific or appear late. You should therefore always pay attention to your dog's behavior and well-being and consult a vet if you suspect anything. Some signs of a vitamin D deficiency or an overdose are

• Ifdeficient: weak bones and teeth that break or fall out easily; muscle weakness and tremors; nervousness and anxiety; susceptibility to infections and poor wound healing; growth problems in puppies.
• In case of anoverdose: increased thirst and increased urination; vomiting and diarrhea; loss of appetite and weight loss; lethargy and depression; rapid heartbeat and shortness of breath; bone pain and joint swelling.