Vitamin D Poisoning in Cats

What is vitamin D poisoning?

Vitamin D is necessary for the body to absorb calcium, a mineral essential for healthy bones, muscle movement, nervous system function, and immune system function. Excessive amounts of vitamin D may result in poisoning. There are two forms of vitamin D: vitamin D2 (ergocalciferol) is produced by plants, fungi, and yeasts, while vitamin D3 (cholecalciferol) is produced by animals.

Poisoning commonly occurs when cats ingest rat and mouse poisons (rodenticides) containing cholecalciferol or supplements containing either form of vitamin D. Vitamin D2 (ergocalciferol) has a much wider margin of safety than vitamin D3 (cholecalciferol) and larger amounts are generally tolerated better by animals. 

Many topical psoriasis medications contain potent amounts of vitamin D (calcipotriene, tacalcitol or calcitriol) and poisoning can occur when cats lick the cream off someone’s skin or directly from the product tube. Improperly formulated pet foods, both commercially produced and homemade, have also resulted in poisoning.

What are the signs of vitamin D poisoning?

Signs of vitamin D poisoning typically start 12–36 hours after ingestion. The severity of signs depends upon the amount of vitamin D ingested. Vomiting, diarrhea, increased drinking and urination, abdominal pain, depression, and lack of appetite are generally seen with smaller doses. Higher doses can cause elevated levels of calcium and phosphorous in the body, which may result in kidney failure. In addition, severe poisoning may cause increased respiratory rate, difficulty breathing, bleeding in the intestines, slow heart rate, abnormal heart rhythms, and mineralization of body tissues. Without appropriate treatment, death may occur.

How is vitamin D poisoning diagnosed?

Most cases of vitamin D poisoning are diagnosed in cats that have the expected signs and a known or suspected exposure to vitamin D-containing supplements, rat/mouse poisons, or psoriasis medications. Bloodwork that shows elevated levels of calcium, phosphorous, or markers of kidney damage increases the suspicion of vitamin D poisoning. A urine sample may be tested to help assess kidney function. In some cases, specialized testing may be necessary to rule out other causes of elevated calcium.

How is vitamin D poisoning treated?

As with any poisoning, early treatment allows the best chance for a full recovery. If your cat has eaten vitamin D supplements, medications, or rat/mouse poison, contact your veterinarian or Pet Poison Helpline, a 24/7 animal poison control center, at 1-800-213-6680 immediately.

The treatment needed depends on the amount ingested and time since ingestion. Early decontamination and treatment decrease the risk for serious toxicity. If ingestion occurred within a few hours of treatment, the veterinarian may induce vomiting. Inducing vomiting at home in cats should never be attempted because it may cause severe damage to the stomach lining and esophagus. Once vomiting is controlled, activated charcoal may be administered, which can decrease absorption of vitamin D from the gastrointestinal tract. Activated charcoal should only be administered by a veterinarian. Otherwise, aspiration into the lungs and life-threatening changes in blood sodium levels may occur.

Bloodwork is necessary to evaluate calcium, phosphorous, and kidney function. If a low dose was ingested, outpatient care may be sufficient. When higher doses are ingested, hospitalized care may be needed, including intravenous fluids and additional medications to prevent absorption of vitamin D and treat current symptoms.

What care is required after treatment?

Unfortunately, the effects of vitamin D poisoning can last many weeks to months. Bloodwork is typically recommended following discharge from the hospital. If changes to bloodwork occur, monitoring may need to be continued for many weeks. Some cats may require further hospitalized care, since calcium levels may increase again following initial treatment. Kidney damage may occur in cats that develop high calcium levels. They may require long-term management for kidney failure.

Pet Poison Helpline, an animal poison control 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.