Metal toxicosis in horses.

The study discusses the widespread presence of metals in the environment and their impact on horses’ health. It covers acute and chronic effects caused by metals like arsenic, mercury, cadmium, iron, lead and zinc, most commonly resulting in gastrointestinal upset, kidney diseases, musculoskeletal problems, and metal-induced deficiency diseases.

Understanding the Role of Metals in the Environment

• The research identifies that metals are always present in the environment due to their inherent stability and ubiquity.
• Through various chemical processes, these metals do not disappear but are rather redistributed within the environment.
• Metals play a vital role in modern life, forming essential materials when combined with other elements.
• However, inappropriate use or poor distribution of metals can potentially harm all biological systems, including horses.

Effects of Metal Toxicosis in Horses

• Metal toxicosis in horses is usually marked by gastrointestinal upset, especially in cases of acute metal poisoning.
• Arsenic and inorganic mercury are particularly harmful as they can cause severe damage to the gut.
• Cadmium deposition on forage is likely the primary source of metal intoxication in horses, leading to chronic issues like musculoskeletal diseases and kidney problems.
• Racetrack horses often receive iron-containing hematinics, which may result in liver diseases (hepatopathy) if administered excessively.
• Lead poisoning, due to the significant environmental presence of lead, is common in humans and animals, but less frequent in horses. Symptoms in horses include intermittent colic, mild anemia, and peripheral neuropathy.

Specific Cases and Long-term Effects of Metal Toxicosis

• Acute mercury poisoning occasionally occurs in horses due to the frequent use of mercury-containing blistering agents, with clinical symptoms typically related to acute renal failure.
• Long-term excessive intake of zinc is rare but can severely affect young, rapidly growing horses. The problem lies not in the zinc intake itself, but in the resulting copper deficiency, which can lead to a disease affecting the cartilage within the joints and growth plates (physes).