Vitamin D is a fat soluble prohormone. There are two major forms of vitamin D, D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). It is responsible for promoting the mineralisation of bones. It also aids the absorption of calcium & phosphorous by increasing absorption from the digestive tract & reducing urinary calcium loss & regulates blood calcium levels. It is produced in the fur (or skin in humans) upon exposure to sunlight and also ingested in small quantities via food. Foods containing vitamin D include fish, liver, dairy products & egg yolk.

Vitamin D toxicosis (also known as hypervitaminosis D) is caused by the accumulation of toxic levels of vitamin D. The most common causes are cholecalciferol rodenticide poisoning, treatment of hypoparathyroidism (supplementing with vitamin D3), over-supplementation with vitamin D3 in the diet, & ingestion of plants containing calcitriol glycosides.

What are the symptoms of vitamin D toxicosis?

Vitamin D toxicosis causes hypercalcemia (abnormally high blood calcium levels), which results in the calcification of various tissues & the intestinal tract, skeletal abnormalities & eventually renal failure, cardiac upset & GI upset.

  • Vomiting
  • Diarrhea
  • Anorexia
  • Increased thirst
  • Increased urination
  • Depression
  • Pain in bones
  • Gastrointestinal or pulmonary hemorrhage (bleeding from the lungs)

How is it diagnosed?

Your veterinarian will perform a complete physical examination & obtain a medial history from you including questions on possible exposure to rodenticide or vitamin supplementation in the diet.

He may wish to perform the following tests;

Biochemical profile which may reveal hypercalcemia (high blood calcium levels), hyperphosphatemia (high blood phosphate levels), and azotemia (high urea levels in the blood).

X-Ray may reveal mineralisation of certain organs.

How is it treated?

  • Induce vomiting for acute exposure to a rodenticide.
  • Activated charcoal to prevent further absorption.
  • Stop supplementation immediately.
  • IV fluids to treat & correct dehydration if necessary.
  • Reduce serum calcium. This may be accomplished by diuresis (facilitation of increased urine output) with normal saline solution, furosemide or prednisolone.


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