Why can vitamin D3 poisoning be fatal?
Cholecalciferol (D3) poisoning raises blood calcium to toxic levels (hypercalcaemia). Calcium then deposits in the kidneys and soft tissues, causing kidney failure that can appear days after the dose — when the pet already looks better.
About the dose levels
Danger threshold for dogs starts around 0.1 mg/kg (≈4,000 IU/kg); serious poisoning above 0.5 mg/kg. Cat doses are similar. The calculator shows mg per kg.
Danger threshold for dogs starts around 0.1 mg/kg (≈4,000 IU/kg); serious poisoning above 0.5 mg/kg. Cat doses are similar. The calculator shows mg per kg.
Signs to watch for
- Vomiting and loss of appetite within 12–72 hours
- Increased thirst and urination at first
- Lethargy, weakness, depression
- Then reduced urine output — a kidney-failure warning sign
- Muscle tremors in severe cases
What to do right now
- Call your vet or poison control right away — this is time-critical even without symptoms.
- Bring the bottle or bait packaging to confirm the exact IU/mg amount.
- Treatment is aggressive: decontamination, IV fluids and medicines that lower calcium — start as early as possible.
- Blood calcium must be monitored for 2–4 weeks after exposure.
If your pet shows any of the signs above, go to the nearest emergency vet now and call ahead.
For a dose worked out against your pet's weight, use the Vitamin D (Cholecalciferol) Toxicity Calculator.