Vitamin D3 (Cholecalciferol) Poisoning in Cats

Once ingested, vitamin D3 is converted to calciferol. Calciferol causes increased calcium absorption, which may result in mineralization (hardening) of tissues or organs. The kidneys are most susceptible to this calcification; however, the central nervous system, lungs, heart, and gastrointestinal tract are all vulnerable.

Symptoms of vitamin D3 poisoning can be nonspecific, but always warrant medical attention. If ingestion is observed, or symptoms present themselves, it is considered a medical emergency.

Symptoms of tissue and organ calcification depend on the organ targeted.

While vitamin D3 poisoning can be fatal, an indoor cat with no access to vitamin D3 has no risk of developing the toxicosis. Cats are also unlikely to eat nonfood items, making this condition quite rare. Note that the toxic dose for a cat is far lower than it is for people or dogs, due to their smaller size.

The two most common causes of vitamin D3 poisoning in cats are ingestion of rodenticides or human pharmaceuticals. Many rodenticides contain cholecalciferol, and vitamin D3-rich drugs (such as calcitriol), multivitamins, and topical creams can all be toxic for cats.

Poorly formulated cat food can also contain too much vitamin D3, although this is rare.

Symptoms of vitamin D3 toxicosis arise within 1-3 days of ingestion.

Diagnostics include physical examination, blood work, urinalysis, and diagnostic imaging. Specific blood tests measuring calcitriol and calcifediol are required for a definitive diagnosis; however, these tests are not readily available.

If consumption is witnessed, treatment looks to reduce vitamin D3 absorption through decontamination. Options include induction of vomiting or administration of activated charcoal or cholestyramine powder.

Note: Decontamination should always be performed by a veterinarian. It is not safe to induce vomiting or administer activated charcoal at home.

If symptoms have started, treatment aims to reduce blood calcium and phosphate levels. Medications to reduce calcium levels and fluid therapy to improve calcium excretion are the primary methods of treatment.

Prolonged inpatient hospitalization may be necessary to combat ongoing tissue calcification. Additional medications to control seizures, treat heart arrhythmias, and protect the stomach lining may be required depending on the symptoms caused by the toxicosis.

Ongoing IV fluids may also be required to prevent dehydration.

The prognosis for vitamin D3 toxicosis is variable, depending on how much vitamin D3 was consumed and how quickly treatment is initiated. If treatment starts before symptoms are observed, prognosis is good. Prognosis is more guarded if the patient is symptomatic, particularly in cases where tissue mineralization has occurred.

The best way to prevent vitamin D3 toxicosis is to ensure that any vitamin D3-rich products, such as rodenticides or pharmaceuticals, are inaccessible to cats. The condition is not contagious.

D3 toxicosis is not common.

• Oral medication
• Fluid therapy
• Activated charcoal
• Induced vomiting