Zinc exposure in animals

Zinc is an essential trace metal that plays an important role in many biologic processes. Zinc toxicity has been seen in a wide range of animals, most often common in dogs, possibly because of their indiscriminate eating habits. Common sources of zinc include pennies, batteries, automotive parts, paints, zinc-oxide creams, herbal supplements, zippers, board-game pieces, screws and nuts on pet carriers, and the coating on galvanized metals such as pipes and cookware.

Zinc salts are formed in the stomach, absorbed from the small intestine, and quickly distributed to the liver, kidneys, prostate, muscles, bones, and pancreas. Zinc salts have direct irritant and corrosive effects on tissue and interfere with numerous metabolic processes, including the production and function of red blood cells. Diets containing high levels of zinc have caused longterm zinc toxicosis in livestock.

Signs vary based on the duration and degree of exposure. Symptoms of overexposure are loss of appetite, vomiting, diarrhea, lethargy, jaundice, shock, destruction of red blood cells, blood in the urine, heart rhythm abnormalities, and seizures. Lameness has been reported in foals. The liver, kidney, and pancreas can be damaged. Zinc levels can be measured in blood or hair tissues, and changes in the blood and urine reflect the effects on various organ systems.

If diagnosed and treated early, the outlook for animals with zinc poisoning is generally good. Eliminating sources of zinc from the environment is essential to prevent recurrence.

Abstract

Zinc is a crucial trace element that plays a vital role in various physiological functions, including immune function, growth, and reproduction in livestock. Zinc deficiency can lead to various health problems in livestock, such as decreased growth rates, impaired reproductive performance, and increased susceptibility to diseases. In contrast, supplementing livestock diets with zinc can promote health and enhance microbiome balance, leading to improved animal welfare and productivity.

Read the review article, using this link:

https://www.sciencedirect.com/science/article/pii/S2773050623000381

Dog Food Research

Zinc requirements currently available for dogs were defined using data of few studies and apply to healthy dogs, at puppy and adult life stages. Pet food manufacturers use those requirements as guides to formulate balanced dog foods. However, studies that evaluated the zinc content of commercial dog foods revealed a wide variation, with a small percent failing to provide the requirements and a significant number having content above the EU legal limit, defined for supplemented animal feeds. Therefore, strategies for zinc supplementation of dog foods still have scope for improvement. It appears from studies on dog food supplementation that organic sources are more bioavailable and often associated with benefits for dogs’ health, although the effects reported are sometimes contradictory, and more sensitive biomarkers are required. In that sense, the search must continue toward improved bioavailability with sources that can meet dog requirements with a lower amount of supplemental zinc, thus reducing the negative environmental impact of zinc excess.

Article: Pereira AM, Maia MRG, Fonseca AJM, Cabrita ARJ. Zinc in Dog Nutrition, Health and Disease: A Review. Animals (Basel). 2021 Apr 1;11(4):978.