Cholecalciferol (Vitamin D3) Rodenticide Poisoning

What is cholecalciferol poisoning?

Cholecalciferol is one of three main active ingredients found in rodenticides. Cholecalciferol is commonly found as a soft bait and occasionally as a hard block or pellet.

It can be found online, at agricultural stores, and through pest control services. While cholecalciferol may seem like a safer option than anticoagulants, there is no antidote available and the amount in a single block is a severe overdose in nearly all animals.

Vitamin D3 (cholecalciferol) is an essential vitamin that helps regulate calcium and phosphorus in the body. The body synthesizes it when exposed to the sun, but it is also found naturally in food. 

High doses of vitamin D3 cause overactive absorption of calcium and phosphorus from the bones and gastrointestinal (GI) tract, and decrease excretion via the kidneys. This causes severe hypercalcemia (elevated calcium levels in the blood) and hyperphosphatemia (elevated phosphorus levels in blood).

If left untreated, excess calcium gets deposited in the kidneys, heart, blood vessels, lungs and stomach – a process called mineralization that leads to hardening and dysfunction of these tissues. Kidney failure is the most common outcome of untreated cholecalciferol poisoning, but other consequences can include gastrointestinal (GI) ulceration, cardiac arrhythmias (irregular heartbeat), and respiratory distress (trouble breathing). Cholecalciferol and the chemical that the liver changes it to (calcifediol) persist in the body for weeks, resulting in prolonged treatment needs.

What are the clinical signs of cholecalciferol poisoning?

Serious signs of cholecalciferol poisoning may take several days to appear.

• Within the first 24 hours, anorexia, vomiting, lethargy, increased thirst, and increased urination occur.
• As hypercalcemia or hyperphosphatemia develop, the initial clinical signs persist or worsen, and the patient may develop bloody vomiting or melena (dark stool due to digested blood).
• Hypercalcemia and hyperphosphatemia are seen on bloodwork within 24 to 72 hours.

If hypercalcemia is not controlled, mineralization will start between three and seven days after exposure. Clinical signs depend on the site of mineralization. The most common site is the kidneys, resulting in elevated kidney values, continued anorexia, vomiting, diarrhea, increased or decreased urine production, and lethargy. More rarely, mineralization in the heart can result in cardiac arrhythmias, and mineralization in the lungs can result in pulmonary hemorrhage.

How is cholecalciferol poisoning treated?

If a pet ingested cholecalciferol, diagnostics and treatments include monitoring blood work, decontamination, supportive care, and medications to assist in excretion of calcium or to prevent reabsorption of calcium. If hypercalcemia or kidney injury develops, more aggressive medications and fluid therapy are initiated.

What is the prognosis for cholecalciferol poisoning?

Prognosis is good if treatment is started before the onset of hypercalcemia. If hypercalcemia is already present, the prognosis is fair to guarded (uncertain). If treatment is started after kidney failure has developed, prognosis is guarded to poor. Mineralization can reabsorb over time but may cause irreversible damage.

If you suspect or witnessed your pet ingesting cholecalciferol rodenticide, please call Pet Poison Helpline, a 24/7 animal poison center, at 1-855-764-7661, and take your pet to a veterinarian for treatment.

Pet Poison Helpline, an animal poison center based out of Minneapolis, MN, is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals, and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s per-incident fee includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com.