Horse Summer Pasture Associated Laminitis

Summer pasture-associated laminitis (SPAL) is a painful foot condition triggered by consuming high-sugar grass. Understanding risk factors and prevention protects horses from one of the most feared equine conditions.

Key Facts

Laminitis is inflammation of the laminar tissue connecting the hoof wall to the pedal bone, causing intense pain
Summer pasture-associated laminitis is triggered by high non-structural carbohydrate (NSC) intake from rapidly growing grass
Grass NSC levels are highest in the morning and in autumn growth flushes, and after cold nights followed by warm days
Ponies, native breeds, horses with Equine Metabolic Syndrome (EMS), and previously laminitic horses are highest risk
Clinical signs include leaning back on heels, reluctance to move, heat in the hooves, and strong digital pulses
Severe or repeated laminitis can cause permanent rotation or sinking of the pedal bone within the hoof (founder)
Restricted grazing using strip grazing, muzzles, or dry lot management reduces intake in high-risk animals
Testing hay NSC levels helps identify appropriate forage for laminitis-prone horses

Welfare Considerations

Laminitis is one of the most painful conditions horses experience - the inflammatory process within the rigid hoof capsule creates intense, unrelenting pain that prevents normal movement and in severe cases is debilitating. Horses with acute laminitis show obvious pain behaviors including rocking back on their hind legs to relieve front foot pressure, reluctance to move, and distressed facial expressions. Prevention is far preferable to management of established disease, making identification of high-risk horses and implementation of appropriate dietary restriction crucial welfare actions. The welfare cost of laminitis prevention measures (grazing restrictions, muzzling) is far outweighed by the welfare benefit of preventing the acute pain and potential permanent disability of laminitis.

What You Can Do

Identify laminitis risk factors in your horses including breed, body condition, and metabolic status
Implement spring and autumn grazing management to limit high-sugar grass intake in at-risk horses
Work with a veterinarian to test horses for EMS if they have a history of laminitis or unexplained weight gain
Monitor pasture growth conditions and restrict grazing during high-risk periods (bright mornings after cold nights)
Maintain appropriate body condition - overweight horses face significantly higher laminitis risk