Vitamin D3 (Cholecalciferol) Poisoning in Dogs

The most common sources of concentrated vitamin D3 consumed by dogs are some particular types of rat poison and high-potency vitamin supplements, like prenatal vitamins.

Vitamin D3 ingestion can be life-threatening, and as such must be treated as an emergency.

If ingestion of a dangerous amount of vitamin D3-containing substance is suspected, even if the animal is not showing symptoms, immediate medical attention is warranted. Early treatment to remove the toxin from the digestive tract before it is absorbed is the best way to prevent poisoning.

Gastrointestinal and other symptoms may develop within 24 hours after ingestion.

Life-threatening elevated blood calcium levels (hypercalcemia) can develop 18 to 72 hours after ingestion.

The severity of vitamin D3 poisoning symptoms varies in accordance with the timing of treatment. When decontamination efforts are successful and a less-than-toxic dose is absorbed, symptoms are mild or non-existent.

Vitamin D3 poisoning is caused by the ingestion of a toxic dose of vitamin D3-containing substances. A number of substances contain high concentrations vitamin D3:

• Some specific types of rat poison
• Cholecalciferol containing vitamins and supplements: dogs are inclined to ingest entire bottles of vitamins if they come in chewable or gummy form
• Psoriasis creams and other human medications

Symptoms of vitamin D3 toxicosis are associated with many other conditions, so diagnosis in the absence of known exposure is difficult.

If ingestion of a toxic dose of a known vitamin D3 containing substance (e.g. cholecalciferol rat poison, vitamins, or psoriasis cream) is witnessed, the diagnosis is self-evident and immediate care is warranted.

If ingestion is not witnessed, a dog showing symptoms associated with vitamin D3 toxicosis typically undergoes the following diagnostics:

• Physical examination
• Blood test
• Complete blood count
• Urinalysis

Routine screening tests may show some changes that suggest vitamin D3 toxicosis (like hypercalcemia), but this is not conclusive. Confirming the diagnosis requires measuring blood levels of cholecalciferol metabolites or demonstrating calcification of tissues during necropsy (post-mortem examination).

Early treatment is focused on gastrointestinal decontamination and supportive care. Decontamination efforts are more effective when performed as soon as possible after ingestion. Decontamination is unlikely to be helpful more than four hours after ingestion.

Decontamination:

• Inducing vomiting (emesis)
• Activated charcoal
• Cholestyramine

Note induction of vomiting and administration of activated charcoal should only be performed under veterinary guidance. There is no safe way to induce vomiting in dogs at home.

Additional therapies include: :

• Fluid therapy
• Diuretics
• Glucocorticoids
• IV administration of intralipid emulsion
• Medications to treat hypercalcemia and hyperphosphatemia

The prognosis for vitamin D3 toxicosis varies greatly and is influenced by the timing of treatment and the formulation of the vitamin D3 ingested.

The best way to ensure a positive outcome is early medical attention and gastrointestinal decontamination.

If the dose is sufficiently large, life-threatening hypercalcemia develops and the prognosis is poor.

Vitamin D3 toxicosis is not contagious. Vitamin D3 poisoning is completely preventable by removing the possibility of ingestion of vitamin D3-containing substances. Strategies include:

• Diligent storage of cholecalciferol rodent poisons
• Diligent storage of vitamin D supplements and vitamin D-containing medication
• Always contacting a veterinarian before giving a pet vitamin supplements

Rates of vitamin D poisoning are on the decline as use of these rodenticides is decreasing. Animals living in rodent-infested areas are more likely to ingest rat poison and develop vitamin D toxicosis.

• Gastrointestinal decontamination
• IV fluid therapy
• Diuresis
• Glucocorticoids
• Cholestyramine
• Aluminum hydroxide
• Bisphosphonates