CEPS/Veterinary Extension
2938 Vet. Med. Basic Sciences Bldg.
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907

By Linda March
Information Specialist
University of Illinois
College of Veterinary Medicine

Laminitis is a very painful and serious disease that can cause lameness in horses. "The laminae is the support of the bony column in the foot. When this supportive lining between the hoof wall and the bone becomes inflamed, it is called laminitis," explains Dr. Mark Martinelli, an equine veterinarian at the University of Illinois College of Veterinary Medicine in Urbana.

There are two layers of laminae in the hoof. The layer of the laminae next to the bone --called the sensitive laminae -- contains the blood. The layer next to the hoof wall has no blood or nervous tissue and is called the insensitive laminae.

"There is limited space in the hoof wall," notes Dr. Martinelli. "When the sensitive laminae becomes inflamed it creates a lot of pressure and can cause pain and instability."

Major changes in normal gut bacteria produced when a horse eats too much grain, or grazes lush pasture, or when a mare has a retained placenta may cause laminitis. Illnesses like infectious diseases, colic, or a surgery may trigger the disease. Stress seems to be a major motivator of laminitis. Even the stress of transportation may cause laminitis. Overweight animals and especially ponies are more prone to get laminitis.

Trauma to the hoof or foot may also be a cause. If the horse is worked repeatedly on hard ground or pavement, laminitis may develop. Dr. Martinelli notes that there are also cases where there is no apparent reason for the horse to have laminitis, but it is lame.

Most cases of laminitis are treated with drugs that reduce the pain as well as the swelling. Heavy bedding of straw or sand may be used in the horse's stall to help relieve the pressure on the foot. Good foot care is required; special shoes with pads and/or support bars are sometimes used to help treat laminitis.

Laminitis can result in founder. "Founder is the Maritime term for 'sinking'," Dr. Martinelli explains. "When a horse has foundered, its pedal (foot) bone has changed orientation in the hoof."

Founder is often a result of laminitis. The disruption of the support becomes severe enough that it allows the bone to either sink down into the hoof more, or change the angle of alignment with the hoof wall. Both of these changes are permanent and make laminitis a chronic problem.

Once this kind of a change has occurred, the owner must continually have the animal's hooves correctively trimmed. The farrier shapes the hoof to regain the correct orientation of the bone to both the hoof wall and the ground.

To prevent laminitis, Dr. Martinelli recommends, "Use general good management practices, such as regular feeding schedule, trimming, vaccinations, and deworming. Lock up the grain and make sure the horse can't get into it to guard against grain overload."

Laminitis can be a one-time illness and manageable, or it may become chronic depending on the situation. If your horse shows signs of lameness, or you have any questions about laminitis, call your equine veterinarian.