TL;DR: Vitamin D toxicity is a life-threatening emergency that causes organ calcification and kidney failure in dogs. Seek immediate veterinary care if your dog ingests supplements or rodenticides, even if they aren't showing symptoms yet.
What is vitamin D toxicity and how does it affect my dog?
Vitamin D toxicity, often caused by the ingestion of human supplements or cholecalciferol-based rodenticides, is a dangerous condition for dogs. While essential in tiny amounts, concentrated Vitamin D3 causes a dog's body to retain excessive calcium and phosphorus. This chemical imbalance leads to the calcification of internal organs, including the heart, lungs, and kidneys.
Is vitamin D ingestion a medical emergency for my dog?
- Vitamin D ingestion is a life-threatening medical emergency with a high urgency level.
- Unlike some toxins, this poisoning can cause silent, irreversible damage to the kidneys within 24 to 72 hours.
- You must contact an emergency veterinarian or a pet poison helpline immediately, even if your dog is not yet showing symptoms.
Why should I take a photo of the supplement label for my veterinarian?
- Take a clear photo of the supplement bottle's label, specifically the dosage information (IU or mg per pill) and the ingredient list.
- Sharing this photo with your veterinarian or triage specialist allows them to calculate the exact milligrams per kilogram ingested.
- This calculation is vital for determining the level of toxicity and the specific treatment protocol required to save your dog's life.
Clinical Context (Merck Veterinary Manual)
In dogs, cholecalciferol (vitamin D3) toxicosis can occur at doses as low as 0.5 mg/kg, despite the reported oral LD50 of 88 mg/kg. Within 12 hours of significant exposure, clinical signs such as vomiting, depression, polyuria, polydipsia, and hyperphosphatemia may be observed, followed by hypercalcemia and acute renal failure within 24-48 hours. Necrosis and mineralization may be evident in the kidneys, heart, and GI tract. Initial treatment should focus on decontamination, including multiple doses of activated charcoal with a cathartic, and assessment of baseline calcium, phosphorus, BUN, and creatinine. If clinical signs of toxicosis and significant hypercalcemia/hyperphosphatemia develop, treatment should include saline diuresis, furosemide, corticosteroids, and phosphate binders. In refractory cases of hypercalcemia, specific agents such as salmon calcitonin or pamidronate may be considered.
Chapter: Toxicology
Source: The Merck Veterinary Manual, 11th Edition (Page 3031)