The research involved determining the reference intervals of trace mineral and toxic element concentrations in horse livers, gathered from two Netherland slaughter facilities. Notably, the study uncovered high levels of the element Cadmium, exceeding European regulatory limits in 89% of the sampled livers.

Methodology

• The study collected liver samples from 122 healthy horses at two separate slaughter facilities in the Netherlands. These samples were taken in the spring and fall of 2021. The age and sex of each horse were recorded at the time of sampling.
• The team quantified the concentrations of several elements – arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, vanadium, and zinc – within the liver samples. They used Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) following an initial nitric acid digestion process.
• The Reference Value Advisor software was used to calculate the detected levels’ reference intervals.

Findings

• There was no significant difference in the concentrations of most of these elements between sexes or across different seasons, indicating that these variables did not have a substantial influence on mineral or heavy metal accumulation in horse liver tissue.
• Cadmium concentrations in horse liver samples were found to be alarmingly high. About 89% of the liver samples contained cadmium concentrations exceeding the European Union’s maximum residue limit of 2 milligrams per kilogram dry weight, suggesting that Cadmium exposure or accumulation is a widespread issue among horses in the studied regions.
• A set of positive and negative significant correlations were identified among certain elements. Iron, molybdenum, lead, and vanadium showed significant positive correlations with each other. This suggests that the presence or accumulation of one of these elements in the liver tissue could associate with higher concentrations of the others. Conversely, manganese and iron showed a significant negative correlation, indicating that higher iron levels might associate with lower manganese concentrations and vice versa.

Implications

• This study provides foundational data for establishing reference intervals of trace mineral and heavy metal concentrations in horse livers. Such information could be beneficial for veterinary medicine, nutritional assessments, and understanding potential environmental exposure or toxicity issues affecting equine health.
• The unexpectedly high Cadmium levels found in the majority of liver samples highlight a potential health concern for horses in the Netherlands and possibly wider Europe. Further investigations are needed to locate the sources and pathways of Cadmium exposure and determine its impacts on equine health and wellbeing.