[Seasonal and national differences in the selenium supply of horses across Europe]

Evaluation of the differences in the selenium supply to horses across Europe.

Serum samples from 137,152 horses all over Europe, which had been sent by veterinarians to IDEXX Vet Med Labor between January 1st 2006 and December 31st 2011, were routinely analyzed for the selenium concentration by means of ICP-analytic.

The selenium content of the soil appears to play a key role in the selenium supply to horses. Countries closer to the ocean provided a better selenium supply than countries in central Europe. The best selenium supply can be seen in Denmark and in the Netherlands. The lowest values are obtained from Austria and Luxembourg. Furthermore, very large differences exist in the selenium supply in different regional areas within a country. This is particularly obvious across the German federal states, with a very good supply in the western areas and a very poor supply in the eastern states. The north-south divide is less obvious, similar to the selenium content of the soil. A very poor situation exists for central Austria, where more than 50% of the equine samples revealed an undersupply.

Individual horse-keeping and feeding represent key points in the selenium supply. Because of the differences in the selenium concentrations in pasture, silage and hay, and due to the lack of routinely performed analysis of the mineral content of food, it is extremely difficult from a management point of view to precisely adapt the intake of minerals. Hence, serum analyses of selenium in horses are very important and should be performed annually. In the case of an undersupply, selenium has to be supplemented with mineral food.