Trace Element Analysis in Sera of Horses with Allergic Dermatitis and in Matched Healthy Controls with Special Attention to Zn, Ni and Ti

The most common allergic dermatitis of the horse is associated with hypersensitivity to insect bites. A purely hereditary-based background to this allergic pruritus has not been shown, and so far, it is not fully understood why some horses are more susceptible than others. Although altered zinc levels have been detected in many inflammatory and allergic disorders, changes in various trace elements have not been widely investigated in horses with allergic dermatitis. Therefore, the purpose was to analyse trace element profiles in the sera of 8 affected and 8 matched healthy horses and to further assess whether the profiles change after therapy of the affected animals. Sera were collected both before and after therapy of the eczema horses. Samples were analysed by inductively coupled plasma mass spectrometry for their iron (Fe), copper (Cu), zinc (Zn), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co) and nickel (Ni) content. Concentrations of Zn and Ni were significantly lower in eczema than in healthy horses (p = 0.0089 and p = 0.0018, respectively). In addition, concentrations of Fe, Zn and Ni displayed significant inverse associations with the severity of clinical signs (p = 0.0075, p = 0.0397 and p = 0.0011, respectively). After a 4-week therapy, no significant differences were found between the groups. Concentrations of Ti were exceptionally stable both between the horses and over time. Horses with allergic dermatitis have alterations in their trace element profiles in comparison with healthy horses. Alterations seem to diminish when clinical signs are regressing.