Laminitis
Laminitis is a vascular and metabolic disease associated with a breakdown within the laminae which secure the coffin bone/distal phalanx to the hoof wall. Inflammation interferes with the wall and bone bond. Laminitis begins when bacterial endotoxins and lactic acid are released into the bloodstream.
The endotoxins and lactic acid dilate the large arteries and cause constriction of the small capillary vessels that nourish the laminae. Deprived of blood, the laminae swell, causing tissue damage because of the rigidity of the hoof wall.
The coffin bone may become detached from the wall, rotate, or sink, and often penetrates the sole. In acute laminitis, the horse is obviously lame and may refuse to stand or walk. Chronic laminitis occurs when displacement of the distal phalanx occurs, but no active laminar necrosis is present. Horses with chronic laminitis are subject to recurrent episodes of acute laminitis.
The terms laminitis and founder are often used interchangeably by authorities. However, founder usually refers to a chronic or long-term condition associated with rotation of the coffin bone, while acute laminitis refers to symptoms associated with a sudden attack, including pain and inflammation of the laminae.
Symptoms
- Lameness, especially when horse is turning in circles
- Heat and increased digital pulse in feet
- Reluctant or hesitant gait
- "Sawhorse" stance
- Refusal to stand or walk
- Pain in toe region when hoof testers are applied
- Dropped soles
- Rings in hoof wall
- Bruised soles
Causes
Laminitis is often caused by conditions in another part of the horse's body. Digestive upsets due to grain overload, abrupt changes in the diet, or sudden access to excessive forage are feed-related causes. .
High fever or illness, severe colic, retained placenta after foaling, and prolonged doses of cortcosteroids are medical issues that are known to cause laminitis.
In addition, consumption of cold water by an overheated horse, excessive concussion to the feet, excessive weight bearing on one leg, and bedding that contains black walnut shavings have all been identified as causes of laminitis. .
These metabolic and vascular-related stresses allow endotoxins and lactic acid to be released into the bloodstream, affecting the arteries and smaller capillaries that nourish the feet, including the laminae. .
Prevention
Preventing laminitis is accomplished through proper horse management, with consistent practices as to feeding, routines, disease prevention, and good health care.
Avoiding feeding excesses, making sure the horse is kept at a reasonable weight, and limiting time in pastures during exceptionally lush growth will help prevent the development of laminitis. Horses should have unlimited access to fresh, clean water, except immediately after exercise when the amount and temperature should be regulated.
When making changes to routines and amount of exercise, go slowly and progressively. Avoid excessive concussion to feet and work-outs on rocky, hard, uneven terrain.
Illnesses, digestive upsets, and primary foot diseases should be addressed immediately before complications can occur that might lead to secondary illnesses or conditions, such as laminitis.
Treatment
Treatment of laminitis depends on the risk factors involved and the severity of the condition. Dietary restrictions to prevent overeating and too much weight gain are important. Administering drugs, such as antibiotics to fight infection, vasodilators to improve blood flow to the feet, anti-inflammatories, and painkillers may be recommended by the attending veterinarian.
Stabling the horse on soft ground, such as sand or shavings, encouraging the horse to lie down to relieve pressure on the feet, and corrective shoeing can be effective in both treating and preventing laminitis.
A certain amount of exercise on a daily basis to encourage blood flow into the affected area is also important. The healing process for laminitis is often long term, taking up to two years in severe cases. Regular examinations by a veterinarian can determine the extent of healing and help develop a timetable for return to full activity.
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