Vitamin D Toxicity Calculator for Dogs
Merck Veterinary Manual reports vitamin D3 (cholecalciferol) poisoning signs in dogs from doses as low as 0.1 mg/kg, with dangerous calcium rises and soft-tissue mineralization above 0.5 mg/kg, so call your vet after any large supplement or rat-bait exposure. (Merck Veterinary Manual; ASPCA APCC Toxicology Brief)
Vitamin D toxicity calculator
Educational estimate from published toxicology references. Not veterinary advice. If in doubt, call your vet.
Risk level (example)
Call your vet
Estimated dose: 0.092 mg/kg
- Call your vet or a poison hotline now; blood calcium checks may be suggested.
- Note the product, amount and time eaten; keep the packaging.
- Do not induce vomiting unless a veterinarian tells you to.
Emergency line
ASPCA APCC (888) 426-4435, fee may apply · Pet Poison Helpline (855) 764-7661, fee may apply
How thresholds are set: Merck Veterinary Manual reports clinical signs from cholecalciferol (vitamin D3) doses as low as 0.1 mg/kg and calcium/phosphorus rises leading to soft-tissue mineralization above 0.5 mg/kg; it lists a reported acute lethal dose of 13 mg/kg. ASPCA APCC reports signs at 0.5 mg/kg. 1 mcg = 40 IU; rodent bait at 0.075% contains 0.75 mg per gram. Signs and calcium changes can be delayed (ASPCA APCC describes signs within the first 48 hours).
Source: Merck Veterinary Manual — cholecalciferol (vitamin D3) poisoning; ASPCA APCC Toxicology Brief — cholecalciferol poisoning (Veterinary Medicine)
Educational estimate from published toxicology references. Not veterinary advice. If in doubt, call your vet.
Result tiers and what to do now
Call your vet — Below ~0.1 mg/kg
Call your vet or a poison hotline for advice; vitamin D never shows a ‘monitor only’ result here. (Merck Veterinary Manual)
Call your vet now — ~0.1–0.5 mg/kg
Call right away; Merck reports signs from 0.1 mg/kg and vets commonly decontaminate and check calcium. (Merck Veterinary Manual)
Emergency — ≥ ~0.5 mg/kg
Go to the nearest emergency vet now. ASPCA APCC reports signs at 0.5 mg/kg and Merck reports mineralization above it. (ASPCA APCC Toxicology Brief)
Call for help
Call your vet or an emergency clinic. ASPCA Animal Poison Control Center (888) 426-4435 or Pet Poison Helpline (855) 764-7661 (fees may apply). Never induce vomiting without a vet's say-so.
Dose by dog weight
| Dog weight | 0.1 mg/kg (signs) | 0.5 mg/kg (mineralization) | 0.075% bait at 0.5 mg/kg |
|---|---|---|---|
| 5 lb (2.3 kg) | 0.23 mg (9,072 IU) | 1.13 mg (45,359 IU) | 1.5 g bait |
| 10 lb (4.5 kg) | 0.45 mg (18,144 IU) | 2.27 mg (90,719 IU) | 3 g bait |
| 20 lb (9.1 kg) | 0.91 mg (36,287 IU) | 4.54 mg (181,437 IU) | 6 g bait |
| 40 lb (18.1 kg) | 1.81 mg (72,575 IU) | 9.07 mg (362,874 IU) | 12 g bait |
| 80 lb (36.3 kg) | 3.63 mg (145,150 IU) | 18 mg (725,749 IU) | 24 g bait |
Conversions: 1 mcg = 40 IU; 1 mg = 1,000 mcg; 0.075% rodent bait = 0.75 mg per gram. A single 14–28 g bait block contains 10.5–21 mg (Merck). Published ranges are not safe allowances.
Frequently asked questions
How much vitamin D is toxic to a dog?
Merck reports cholecalciferol signs from doses as low as 0.1 mg/kg (4,000 IU per kg) and calcium/phosphorus rises causing soft-tissue mineralization above 0.5 mg/kg. ASPCA APCC reports signs at 0.5 mg/kg.
How do I convert IU to mg?
1 mcg of vitamin D3 equals 40 IU, and 1 mg equals 1,000 mcg. So a 5,000 IU softgel holds 125 mcg, or 0.125 mg.
Why are vitamin D rat baits so dangerous?
Cholecalciferol baits are usually 0.075% (0.75 mg per gram), so a single bait block of 14–28 g can hold 10.5–21 mg — enough to harm a large dog.
When do symptoms appear?
ASPCA APCC describes signs such as vomiting, lethargy and weakness within the first 48 hours, and Merck notes calcium changes can be delayed, so call your vet before signs appear.
Related calculators
Sources
- Merck Veterinary Manual — cholecalciferol (vitamin D3) poisoning
- ASPCA APCC Toxicology Brief — cholecalciferol poisoning (Veterinary Medicine)
- Pet Poison Helpline
Educational estimate from published toxicology references. Not veterinary advice. If in doubt, call your vet.