29 April 2026: Hypomagnesaemia in cattle and sheep
Updated 30 April 2026
Applies to England, Scotland and Wales
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Situation
APHA has diagnosed and been made aware of several recent cases of hypomagnesaemia in grazing cattle and sheep. It is likely that, in some areas, the recent warmer spring weather contributed to fast growing pastures that are high in moisture and potassium that inhibits magnesium (Mg) absorption.
Details
Clinical signs range from nervousness, high head carriage, ear twitching, muscle tremors, and lowered milk yield in the early stages, progressing to staggering, teeth grinding, collapse, paddling, convulsions, and rapid or sudden death. Hyperaesthesia and aggression in calved cows can also be seen. For cases of sudden death, other causes including anthrax should be considered.
Diagnosis is based on clinical signs and Mg levels in blood or ocular fluids. Sampling of cohorts (with care) may also be indicated to determine herd or flock levels.