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.
Symptoms of vitamin-d poisoning
- 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 is already showing symptoms, don’t wait for a calculator result — call your vet or the ASPCA Poison Control center (888) 426-4435 immediately.
Sources & further reading
- ASPCA Animal Poison Control — pet poison database & dosage references
- Pet Poison Helpline — toxicology triage guidelines
- Merck Veterinary Manual — toxicology monographs
- Vets Now (UK) — emergency toxicosis guidance