Vitamin D Poisoning in Cats

By Renee Schmid, DVM, DABVT, DABT; Ahna Brutlag, DVM, MS, DABT, DABVT; Rania Gollakner, BS, DVM, MPH

What is vitamin D poisoning?

Vitamin D is necessary for the body to absorb calcium, a mineral that is essential for healthy bones, muscle movement, nervous system function, and immune system functions. Excessive amounts of Vitamin D may result in poisoning. There are two forms of vitamin D. Plants, fungi and yeasts produce Vitamin D2 (ergocalciferol), 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 more tolerated by animals. Many topical psoriasis medications also contain potent amounts of vitamin D (i.e., calcipotriene, tacalcitol or calcitriol) and poisoning can occur when cats lick the cream off someone’s skin or directly from the tube of product. 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 to the signs above, severe poisoning may also 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 treatments. Blood work showing elevated levels of calcium, phosphorous, or markers of kidney damage increase the suspicion for vitamin D poisoning. A urine sample may be performed to help assess kidney function. In some cases, specialized testing to rule out other causes of elevated calcium may be necessary.

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 type of treatment needed depends upon 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. Once vomiting is controlled, activated charcoal may be administered. This 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.

Blood work to evaluate calcium, phosphorous and kidney function is necessary. If a low dose was ingested, outpatient care may be sufficient. When higher doses are ingested, hospitalized care including intravenous fluids, additional medications to prevent absorption of vitamin D, steroids, anti-nausea medications, antacids and medications to decrease calcium and phosphorus levels may be needed.

What care is required after treatment?

Unfortunately, the effects of vitamin D poisoning can last many weeks to months. Blood work to monitor calcium, phosphorous and kidney function are typically recommended following discharge from the hospital. If elevations in calcium, phosphorous or kidney values 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 including blood work monitoring, fluid therapy, anti-nausea medications, medications to control blood pressure and antacids.

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 fee of $65 per incident 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

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