Vitamin D for Dogs and Cats

Vitamin D3


Vitamin D3 is necessary to keep your pets healthy. Vitamin D is a fat-soluble nutrient. Vitamin D, also known as calciferol, promotes the absorption of calcium and phosphorus and then helps deposit them in bones and teeth. Research suggests that vitamin D has been linked with lower incidences of cancers and lower rates of immune-related conditions in animals. A recent study funded by the Veterinary Diagnostics Institute, Inc has indicated that deficient levels of vitamin d in dogs increase the incidence of cancerous and non-cancerous tumor growth in studied individuals.

Vitamin D Sources

Vitamin D obtained from sun exposure, food, and supplements, is biologically inert and must undergo two hydroxylation reactions to be activated in the body. Without sufficient vitamin D, bones can become thin, brittle, or misshapen. Vitamin D is made in the skin when the UV index is greater than 3. This occurs daily during the spring and summer seasons in temperate regions and adequate amounts of vitamin D can be made in the skin after only ten to fifteen minutes of sun exposure a day. Animals obtain their vitamin D by licking their fur and ingesting the vitamin D that is produced from oil glands that transfer oil from the skin to the fur.

Diet is the most common way that pets get their vitamin D. Here is a list of the most common food sources of vitamin D.

  • Mackeral
  • Salmon Oil
  • Cod Liver Oil
  • Herring
  • Salmon(wild-caught)
  • Tuna
  • White Fish
  • Sardines
  • Anchovies
  • Egg Yolks


Conversely to humans, the most common problem seen in cats and dogs is too much vitamin D which can lead to toxicity. Because vitamin D is fat soluble, it is readily absorbed by the body. Any excess vitamin D that your pet gets in their diet is stored in the liver. The most common source of vitamin D poisoning in pet is ingestion of rodent poisons.

Symptoms of Vitamin D Toxicity

  • Abdominal Pain
  • Vomiting
  • Excess Drooling
  • Diarrhea
  • Lethargy
  • Excess Thirst
  • Excess or Decreased Urination


So, how does your pet obtain Vitamin D? Dogs and cats obtain a very small amount of vitamin D thru exposure to the sun. Pets rely almost entirely on receiving it from the foods they consume. Most commercial dog and cat foods contain the minimum amount recommended by the Association of American Feed Control Officials (AAFCO) and additional supplementation is rarely needed.

Vitamin D3 Recommendations for Pets

The recommended dose of vitamin D3 for dogs and cats is 227 IU per pound of food served. Toxic levels of vitamin D3 in dogs are reached at over 2700 IU per lb of food a day and over 4,500 IU per lb of food a day for cats, but in order to see symptoms, this amount would need to be given for months.

Vitamin D3 Recommendations for Dogs

Total IUs Daily Daily Food Consumption Dog’s Weight
400 IU 1-1/2 to 2 pounds > 75 pounds (large)
300 IU 1 to 1-1/2 pounds 30 – 75 pounds (medium)
100 – 200 IU 8 oz. to 12 oz. < 30 pounds (small)

Vitamin D3 Recommendations for Cats

Vitamin Recommended Minimum Daily Dose for Adult Cats Toxic Dose (This dose must be given daily for months to create toxicity.)
D 227 IU/lb of food consumed on a dry matter basis 4,545 IU/lb of food consumed on a dry matter basis

•  Veterinary Diagnostic Institute: Vitamin D (canine/feline)
•  Vitamin D levels predict survival chances for sick cats, study finds

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