What is laminitis and what causes it? Laminitis is an inflammatory condition of the soft tissues of the hoof (the laminae) that causes variable degrees of lameness from acute (sudden) onset, severe lameness and recumbancy (laying down) to a more chronic, low-grade lameness. Laminitis most often affects both front feet but can affect all four feet. There are several potential causes of laminitis but the most common are:
- metabolic diseases such as Cushing’s disease or Equine Metabolic Syndrome
- endotoxemia secondary to grain overload or a systemic inflammatory condition such as pneumonia or diarrhea
- supporting limb laminitis when a horse bears more weight on one limb due to injury in another limb
- even if a metabolic disease has not been identified, overweight horses seem to be at risk
At its most basic, think of the horse’s foot as similar to your finger tip. There is a hard outer nail, a bone, and pink connective tissue in between representing the laminae. Laminitis literally means “inflammation of the laminae.” Imagine the pain you have if you hit your finger really hard or you get a splinter under your nail. These things cause “inflammation.” In laminitis we are not yet sure what causes the inflammation at a cellular level, but suffice it to say, there is tremendous pain and tissue injury associated with it. If the connective tissue breaks down as a consequence of this tissue injury, the connection between the hoof and the bone is lost. This is somewhat similar losing your toenail after your horse steps on it.
Signs of laminitis: Outward signs of laminitis that you may observe include:
- generalized stiffness
- “walking on eggshells”
- shifting weight from foot to foot
- laying down more than usual
- hesitant or resistant to walk
- rocking back on hindquarters
The external appearance of the hoof can also give clues. “Founder rings” or parallel horizontal ridges in the hoof wall can be indicative of previous episodes of laminitis. Changes in the appearance of the white line on the solar surface of the foot are also common and may be brought to your attention by your farrier. These external changes are only apparent weeks to months after an acute episode.
The take home message is that laminitis is considered an emergency. If your horse is exhibiting any of the above signs, he or she should be seen by a veterinarian right away.