What is vitamin A poisoning?
Vitamin A is an essential vitamin for all species of mammals, birds, and fish. It is necessary for proper growth, vision, reproduction, and skin health. Vitamin A poisoning most commonly occurs when pets are fed raw liver, cod liver oil, or other supplements rich in vitamin A over several weeks to months. Poisoning from a single, very large dose of vitamin A, such as a whole bottle of vitamin supplements, is less common but can occur. Cats are more susceptible to vitamin A poisoning than dogs.
Surprisingly enough, polar bears, seals, and walruses accumulate large amounts of vitamin A in their livers, which may result in poisoning if ingested by animals and humans.
What are the clinical signs of vitamin A poisoning?
The signs of vitamin A poisoning can be sudden or delayed in onset. When very large doses of vitamin A are ingested, cats may develop rapid signs of vomiting, drowsiness, irritability, and peeling of the skin.
More commonly, oversupplementation of vitamin A for weeks to months causes a delay in the development of signs. Poor hair coat, rough or dry skin, weakness, weight loss, constipation, excessive bone development, and painful or limited movement are all signs of vitamin A poisoning. Excessive vitamin A intake during pregnancy has been associated with cleft palate formation and other fetal abnormalities. Kittens may develop swelling and inflammation of the gums as well as loose or retained baby teeth. If you believe your cat has ingested vitamin A, please call your veterinarian or Pet Poison Helpline, a 24/7 animal poison control center, right away.
How is vitamin A poisoning diagnosed?
Most of the time, a diagnosis is based on a history of excessive vitamin A supplementation and the development of expected clinical signs. X-rays may show excessive bone formation, especially in the area of the neck, chest, and joints. Elevated levels of vitamin A in the blood will also support the diagnosis. Blood work to evaluate organ function may also be helpful.
How is vitamin A poisoning treated?
If a single, large ingestion of vitamin A 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 A by the gastrointestinal tract. Activated charcoal should only be administered by a veterinarian. Otherwise, aspiration into the lungs and life-threatening changes in sodium levels may occur.
"Activated charcoal should only be administered by a veterinarian."
Chronic oversupplementation is typically treated by reducing vitamin A intake through stopping the feeding of raw liver, cod liver oil, or vitamin A supplements. Feeding a commercially prepared balanced diet or a balanced homemade diet formulated by a veterinary nutritionist is recommended. Once the diet is corrected, blood levels of vitamin A should return to normal within a few weeks. Vitamin A is stored in the liver, and elevated liver values may be present for years.
Although excessive bone growth is not reversible, mobility and comfort may improve once vitamin A levels normalize. In some cases, long-term pain management may be needed.
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