Vitamin D Supplement
ToxicVitamin D causes hypercalcemia and acute kidney injury in dogs. Merck reports signs of toxicosis at doses as low as 0.5 mg/kg — about 20,000 IU/kg — which high-potency capsules reach in just a few pills.
This food guide has not been reviewed by a veterinarian. It summarises general information from sources and should not be used to decide whether a food is suitable for an individual dog or to assess an emergency.
Check before feeding
Do not offer as a treat
There is no recommended treat portion for this hazardous item. If swallowed, contact a vet with the amount, time and product details. Do not induce vomiting yourself.
Signs and health concerns
This list includes both observable signs and conditions identified through examination or testing. It cannot establish the cause or whether an exposure is safe.
- Vomiting
- Reduced activity and responsiveness
- Increased urine volume
- Increased thirst
- Loss of appetite
- Weakness
- High blood calcium
- Raised nitrogen waste in blood
- Dehydration
- Blood in stool
More about this food
Vitamin D is fat-soluble, so it accumulates rather than washing out in urine. That is why the usual "a little extra won't hurt" logic fails here. The Merck Veterinary Manual reports that clinical signs of cholecalciferol toxicosis have occurred at doses as low as 0.5 mg/kg, and that the oral LD50 in dogs has been reported as 88 mg/kg.
Labels use IU, not milligrams, so convert before you panic or relax. One milligram of cholecalciferol is 40,000 IU, which makes Merck's 0.5 mg/kg equal to 20,000 IU/kg. For an 11 lb dog that is 100,000 IU: a hundred 1,000 IU softgels, twenty 5,000 IU softgels, or just two of the 50,000 IU prescription capsules people take weekly. Potency, not the words on the front of the bottle, decides how bad this is. So the first job is counting what is left and working out the maximum IU that went missing.
Calcium is what does the damage. Cholecalciferol converts to active metabolites, blood calcium climbs, and calcium and phosphorus deposit in tissue — Merck notes the kidneys, heart, and GI tract can become necrotic and mineralized. Vomiting, depression, and polyuria/polydipsia can develop within 12-48 hours, with hypercalcemia and azotemia at 24-48 hours and acute kidney injury later. The first sign is often nothing more dramatic than a dog draining the water bowl and asking to go out, which is exactly why it gets missed.
This is also a slow illness to treat. Merck notes that calcifediol's 16-30 day half-life means stabilization takes days, and lists cholestyramine to block absorption, saline diuresis with furosemide, corticosteroids, phosphate binders, and pamidronate for persistent hypercalcemia. All veterinary decisions.
What to do now: note the product, the IU per softgel, how many are missing, the time, and your dog's weight, then call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435 and bring the bottle. Watch for the more concentrated sources in the same house — cholecalciferol rodenticide blocks and multivitamins that also contain iron are separate emergencies. Do not induce vomiting at home, and understand that a dog who looks fine tonight may still need bloodwork at 24 and 48 hours.
Frequently asked questions
- My dog swallowed one 1,000 IU vitamin D softgel.
- For an 11 lb dog that is about 200 IU/kg, far below Merck's 20,000 IU/kg (0.5 mg/kg) figure. Still check the label, because 5,000 IU and 50,000 IU products change the math completely, and call your vet with the count if more than one is missing.
- It has been a day and now she is drinking constantly.
- Polyuria and polydipsia are the early signs Merck places at 12-48 hours, and hypercalcemia with rising kidney values follows at 24-48 hours. Do not restrict her water. Call your veterinarian now — this is the point where bloodwork for calcium and kidney values changes the outcome.
- He got into a multivitamin. Is vitamin D the only thing to worry about?
- No. Multivitamins combine vitamin D with iron, zinc, and vitamin A, and each has its own toxic profile. Iron-containing formulas, including prenatal vitamins and children's chewables, are a separate emergency. Bring the whole label and your best count of what is missing.