Zinc Poisoning in Pets

By Renee Schmid, DVM, DABVT, DABT; Ahna Brutlag, DVM, MS, DABT, DABVT; Pamela Huyck, CVT

Zinc is an essential mineral that is needed for DNA production, growth, wound healing and immune function. Since zinc is not made in the body, it must be consumed in the diet. The body requires very small amounts of zinc. Ingesting too much can cause poisoning.

Zinc is commonly found in metal objects including nuts, bolts, zippers, jewelry, galvanized metal, nails, and board game pieces. Ointments, such as diaper rash creams and sunscreen, may contain large amounts of zinc. Because of its effects on the immune system, zinc is commonly available in vitamin supplements, nasal sprays, lozenges, and other over-the-counter cold remedies. In the United States, pennies made after 1982 are made with a core of zinc covered in copper plating. Ingestion of these pennies is one of the most common causes of zinc poisoning in pets.

How much zinc is poisonous to pets?

The amount of zinc required to cause poisoning depends upon the pet’s size, the form of zinc ingested, and how much was ingested. Some forms of zinc are more readily absorbed than others.

A one-time ingestion of zinc oxide cream typically only causes stomach upset. However, repeated ingestion of these ointments over days to weeks can cause poisoning in highly concentrated products.

Ingestion of pennies and other metallic objects is more likely to cause poisoning. This is especially true in smaller pets where it may be more difficult for the object to move out of the stomach. Ingesting as little as 1-2 pennies can result in zinc poisoning.

Simply chewing on galvanized metal wire cages or metal toys has caused zinc poisoning in birds.

A veterinarian or Pet Poison Helpline, a 24/7 animal poison control center, at 1-800-213-6680 should be consulted to assess the risk of poisoning if ingestion of any zinc containing product is witnessed or suspected.

What are the signs of zinc poisoning?

Zinc causes irritation of the gastrointestinal tract. Most pets with zinc poisoning will develop vomiting, diarrhea, depression, and lack of appetite.

Zinc poisoning may cause a low red blood cell count (anemia) by damaging the red blood cells and causing them to break open. It can also decrease the production of new red blood cells. Pets that develop anemia may have weakness, pale gums, increased heart rate, increased respiratory rate and effort, yellow discoloration of the eyes or skin (icterus), orange stool, and red or dark yellow/orange discoloration of the urine.

Pets with more severe poisoning may have damage to the liver, kidneys, heart, or pancreas. In addition, these pets may have increased drinking, increased urination, weight loss, abdominal pain, or organ enlargement. In rare cases, neurologic signs such as incoordination and seizures can occur.

How is zinc poisoning diagnosed?

Most cases are diagnosed in pets with the expected signs and a history of zinc ingestion. Blood work to check the pets red blood cell count, liver and kidney function is often performed. When zinc poisoning is suspected, x-rays of the abdomen may be performed to look for a metallic object in the stomach or intestines. Specialized testing to determine the blood level of zinc can confirm the diagnosis.

How is zinc poisoning treated?

Treatment will depend upon the severity of the pets’ signs. Anti-nausea medications, antacids, anti-diarrheal medications, and fluid under the skin may be all that is needed for pets that ingest a single dose of zinc ointment. Hospitalized care is needed for more severe poisonings. Intravenous fluids, blood transfusions, and medications to bind and remove the zinc from the body (chelation) are possible treatments. If  pennies or other metal objects are still in the stomach, surgical or endoscopic removal is required. Blood work to monitor the red blood cell count, kidney and liver function is needed in pets with severe signs.

What is the prognosis for zinc poisoning?

The outcome depends on many factors including the type of zinc and amount ingested, time to treatment, and severity of the pets’ signs. With early treatment, pets are less likely to develop long term effects. Most pets that ingest zinc ointment will recover fully with appropriate supportive care. Early removal of any metal objects ingested and prompt treatment decrease the risk for serious effects.

Removal of the metal object before organ damage occurs often results in a good outcome. Most pets will recover within 2-3 days of removing the source of zinc. Permanent organ damage or death may occur in pets with severe signs or delayed treatment.

Contacting a veterinarian or Pet Poison Helpline (1-800-213-6680) immediately if zinc ingestion occurs will improve the likelihood of proper treatment and increase the chance of a full recovery.

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

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