# Reference Intervals for Trace Elements in Canine Plasma

## TL;DR

This study establishes reference ranges for trace elements in healthy dogs, which can help in diagnosing and understanding canine diseases.

## Contribution

The study provides the first comprehensive reference intervals for 12 trace elements in canine plasma using a large sample size.

## Key findings

- Reference intervals were established for 12 trace elements in canine plasma using inductively coupled plasma mass spectrometry.
- Significant differences in trace element concentrations were found based on sex, age, and size, though effects were generally weak.
- Cd levels were below quantification in 77% of samples, and no differences were found based on breed or reproductive status.

## Abstract

Trace elements, or microminerals, are essential nutrients for all organisms, playing roles in structural functions and participating in numerous biochemical reactions. Both deficient and excess levels of these elements can be harmful, potentially leading to disease. Evidence from human studies shows that trace elements are implicated in multiple diseases, acting as preventive or predisposing factors and influencing the response to treatment and disease prognosis. For these reasons, trace element levels are increasingly studied in veterinary medicine, particularly in relation to diverse canine diseases. However, few studies have analysed large groups of healthy dogs, and reference intervals have not been established for most trace elements. In this study, 140 canine plasma samples were analysed with the aim of establishing the reference intervals for 13 trace elements. The samples were analysed by inductively coupled plasma mass spectrometry, which has a very low limit of detection for trace element measurement. The influence of biological factors on the variability in element levels was also assessed. The reference intervals established will be valuable for clinical evaluation and future research.

Trace elements are essential for organisms, and their involvement in diverse diseases is increasingly recognised. Interest is increasing in veterinary medicine, particularly in relation to canine diseases. However, reference intervals for trace elements in dogs remain scarce. Plasma samples from 140 dogs were analysed by inductively coupled plasma mass spectrometry to determine the levels of 13 trace elements. Reference intervals (µg/L) were established for the following 12 elements: As, 0.417–8.17; Co, 0.039–1.33; Cr, 2.41–13.3; Cu, 296–790; Fe, 846–3643; Hg, 0.235–2.33; Ni, 0.567–9.04; Mn, 1.90–7.28; Mo, 1.43–12.7; Pb, 0.285–2.82; Se, 200–434; and Zn, 415–1095. However, Cd was below the limit of quantification in 77% of the samples. No differences in trace element concentrations were observed in relation to breed or reproductive status. Statistically significant differences were found in relation to sex (Cu, Mo, Zn), age (Co, Cu, Mo, Mn, Se, Zn), and size (Cu, Mo, Se, Zn); however, the magnitude of these effects varied among elements and was generally weak. Nevertheless, these factors should be considered when assessing trace element status. These reference intervals constitute an important resource for both clinical evaluation and future research.