Evaluation of tear and serum trace elements (copper, selenium, and cobalt) in sheep

Metabolic diseases such as enzootic ataxia, white muscle disease, and white liver disease are among the most important problems of livestock for sheep. The aim of this study was to analyze whether tears can be used as an alternative diagnostic method in determination of diseases that result from lack or excess of copper, selenium, and cobalt. Samples of serum and tears taken from 45 healthy sheep of the Kivircik breed aged between 2 and 4 years were analyzed. The concentrations of copper, selenium, and cobalt were measured in serum and tears as 118.0 ± 36.0, 58.0 ± 15.0, and 0.5 ± 0.3 µg/dL and 16.0 ± 8.0, 7.0 ± 4.0, and 2.0 ± 1.0 µg/dL, respectively, by using inductively coupled plasma optical emission spectrometry. The concentrations of copper and selenium in serum samples were significantly higher than those of tear samples (P < 0.001). However, cobalt concentrations in serum were found to be lower than those in tears (P < 0.001). As a result, the authors suggest that determining cobalt concentrations in tears may be a valuable alternative diagnostic method in the diagnosis of metabolic diseases of sheep, rather than determining the copper and selenium concentrations, which might not be as reliable.