Horse Grass Sickness: A Devastating Disease and Its Welfare Burden

Equine grass sickness is a frequently fatal neurological disease affecting horses at pasture, causing devastating welfare impacts and leaving owners and vets with difficult decisions.

Key Facts

Equine grass sickness (equine dysautonomia) affects horses primarily in the UK, with hotspots in Scotland and northern England
The causative agent is thought to be Clostridium botulinum Type C toxin, though the mechanism is not fully understood
Acute and subacute forms are almost always fatal; only chronic cases have any realistic chance of survival with intensive nursing
Clinical signs include sweating, muscle tremors, difficulty swallowing, gut stasis, and profound depression
Euthanasia is the welfare-appropriate decision for acute and most subacute cases
Chronic cases require weeks to months of 24-hour nursing, including hand-feeding mashes and regular exercise
The Equine Grass Sickness Fund funds research into prevention and early diagnosis

Welfare Considerations

Grass sickness causes intense suffering: horses experience severe pain from gut stasis, inability to swallow, and profound weakness. Recognising when euthanasia is the most welfare-appropriate response requires courage from owners and clear guidance from vets. The chronic form, while potentially survivable, involves weeks of intensive nursing care that is demanding for both horse and carers. Early recognition of clinical signs and prompt veterinary assessment are essential to minimise unnecessary suffering.

What You Can Do

Learn to recognise early signs of grass sickness including sweating, muscle trembling, and difficulty swallowing
Discuss a clear decision-making framework with your vet before any crisis occurs
Avoid moving horses from premises with a history of grass sickness during high-risk spring months
Support the Equine Grass Sickness Fund's research into prevention
Report any suspected grass sickness cases to your vet promptly and participate in surveillance research