Grass Tetany and Histamine

Abstract

THE occurrence, distribution and ætiology of grass tetany in cattle and sheep have already been adequately described^1,2. The most consistent symptom in all cases is a low serum magnesium-level, values below 1 mg per 100 ml. being common. The condition is sometimes accompanied by hypocalcæmia². Nevertheless, severe hypomagnesæmia can be present in some cases without the appearance of clinical symptoms of tetany, which raises the question of the possible occurrence of other causative factors. The high incidence of grass tetany, for example, on young, rapidly growing pastures has given rise to views that some factor may be introduced by the herbage, and Seekles² has even suggested the term ‘nutrition-tetany’ for the condition. This factor may be independent of those which act by reducing availability of magnesium to the animal.