Laminitis: A Serious, Crippling Disease of Horses

Laminitis is a painful inflammation of the tissues, called laminae, which bond a horse’s hoof wall to the pedal (or coffin) bone in the hoof. Laminitis occurs when blood flow to the sensitive and insensitive laminae is disrupted. This weakens the supporting lamina within the hoof, leading to painful tearing of the support structure that suspends the pedal bone within the hoof.

The term acute laminitis is used interchangeably with the term founder. However, these terms describe different conditions. Acute laminitis involves a sudden initial attack of pain and inflammation of the laminae. Founder usually refers to a long-term condition associated with rotation of the coffin bone. 

Causes of laminitis:
  • digestive upsets because of grain overload or abrupt changes in diet
  • grass founder, caused by sudden access to too much lush forage before the horse's system has had time to adapt
  • toxins released within the horse's system
  • high fever or illness
  • severe colic
  • a retained placenta in the mare after foaling
  • road founder, caused by excessive concussion to the feet
  • excessive weight bearing on one leg because another leg has been injured
  • various primary foot diseases
  • bedding that contains black walnut shavings
Risk factors that seem to increase a horse’s susceptibility to laminitis: 
  • heavy breeds, such as draft horses
  • an overweight body
  • large amounts of carbohydrate-rich meals
  • previous episodes of laminitis
  • older horses with Cushing's disease
  • unrestricted grain consumption (In this case, call your veterinarian immediately for help.)
  • horses that have had previous episodes of laminitis
Signs of acute laminitis 
  • lameness: when a horse is either turning in circles or standing
  • heat in the feet
  • increased digital pulse in the feet 
  • pain in the toe region when pressure is applied with hoof testers
  • a hesitant gait
  • a sawhorse stance – in this stance, the hind limbs are placed far under the body and the front feet stretched far forward, to lessen the weight on painful front feet 
Signs of chronic laminitis 
  • rings in the hoof wall that become wider as they are followed from toe to heel
  • stone bruises or bruised soles 
  • seedy toe – a widened white line, with the occurrence of blood pockets
  • dropped soles or flat feet
  • a thick, cresty neck (e.g., cresty neck refers to excessive fat deposits along the top of a horse’s     
  • neck)
  • dished hooves – the result of unequal rates of hoof growth
Management of laminitis
  • Call your veterinarian for advice. The sooner treatment begins, the better the chance for recovery.
  • Treat laminitis as an emergency. 
  • Initial treatment is critical and can dramatically reduce the likelihood of founder.
  • Dietary restrictions:
    • Stop feeding all grain-based feeds and pasture. 
    • Feed only grass hay until advised by your veterinarian. 
    • Do not over-feed your horses.
  • Administer fluids if the horse is ill or dehydrated.
  • Stable the horse on soft ground, such as in sand or shavings, and encourage the horse to lie down. 
  • Do not exercise your horse.
  • Do not starve your horse, as hyperlipidemia may develop. 
  • Do routine hoof care, including regular trimming. 
  • Maintain good general health, including vaccination and deworming.
  • Avoid feeding horses with mould-infected horse hay.
Prevention of dietary-induced laminitis:
  • Implement a dietary control schedule recommended by your veterinarian
  • Avoid grazing lush pastures, especially between late morning and late afternoon hours, since plant sugars are the highest during these times. Restrict pasture intake during spring, or anytime the pasture suddenly greens up. 
  • Reduce the portion of feed, and increase the time between two meals.
  • Provide a modified diet that offers adequate nutrition based on high-quality forage, digestible fibre and oil. 
If you purchase feed from various sources and plan to do feed tests:
  • Ask your veterinarian which feed tests should be performed.
  • Contact Manitoba Agriculture for information about available laboratories and fee schedules, feed sampling information, a feed sampler (auger) and sample bags for feed sample collection.
  • Samples sent through Manitoba Agriculture will be exempt from GST.
  • If you plan to test three or more samples, the laboratory bears the courier charges.
  • For more information, contact the closest Manitoba Agriculture office.