Laminitis and Founder
According to the National Animal Health Monitoring System (NAHMS) 2000 report, 13%
of all horse operations had a horse with laminitis in the previous year and 4.7%
of these died or were euthanized. That makes laminitis second only to colic as a
leading killer of horses.
What is laminitis (and founder)?
Inside the horse’s hoof is a bone called the coffin bone. It’s attached to the hoof
by tiny interlocking fingers, or laminae. A complex sequence of events occurs during
laminitis, but the key events are inflammation of these laminae (therefore the name
laminitis), their death and the death of cells around them. When these tissues die,
the coffin bone is no longer properly supported in the hoof. Then, forces from bearing
weight on the ground as well as from tendons pulling upward on the bone can cause
it to rotate or sink in the hoof. When structural damage like this occurs, the horse
is said to have "foundered."
What causes laminitis?
According to Rustin Moore, DVM, PhD, Dipl. ACVS, who shared his research at the
most recent Bluegrass Laminitis Symposium held January 2007 in Louisville, KY, laminitis
often occurs because of other inflammatory conditions in the body, such as:
- Pasture (carbohydrate) overload
- Grain overload
- Endotoxins in the blood
- Uterine infection or retained placenta
- Metabolic disturbances such as insulin resistance
- Excess weight-bearing on a supporting limb (opposite a limb with a
- Infection of the blood (septicemia)
- Infection of the lungs
- Enterocolitis (inflammation of the small intestine and colon)
What are the signs of laminitis?
Owners should learn to recognize the following, very characteristic appearance of
a laminitic horse:
Shifting of weight from foot to foot
Slight stiffness of gait
Reluctance to move
Classic founder stance: all four feet forward , so hind feet carry more weight
Warm feet, bounding digital pulse
Sweating, high heart and respiratory rates
Lying down and not wanting to get up
Any horse showing these signs should be seen immediately by a veterinarian to confirm
the diagnosis and start emergency treatment which may not only save the horse’s
performance career, but also his life.
How is laminitis treated?
The goal of treating laminitis is to first treat the primary disease that caused
it, then try to limit the inflammation and structural damage that is occurring.
Because the exact sequence of events leading to damage in the foot has not been
completely figured out, treatment can be controversial. Most agree however, that
a nonsteroidal anti-inflammatory (NSAID) medication like phenylbutazone or "bute"
should immediately be given to reduce inflammation, since this seems to be a common
factor in all laminitis cases. Other medications that may be used include vasodilators
like acepromazine, anticoagulants, and antiendotoxins.
The next step is providing mechanical support to the foot, to ensure even blood
flow to all the tissues and try to prevent rotation or sinking. Some do this by
stalling the horse in sand, which provides soft, even support across the whole bottom
of the foot. Others prefer to attach devices directly to the bottom of the foot
to provide "arch support," to elevate the horse’s heels, and to encourage
breakover in a certain area of the foot. Again, most agree that stall rest is critical,
at least for the first few days.
Obviously the veterinarian and farrier must work closely together to provide treatment
to the laminitic horse both in the acute and chronic phases. Baseline and follow-up
radiographs allow the healthcare team to measure the damage and accurately place
and replace support devices.
Can laminitis be prevented?
Approximately half of the horses that develop laminitis are on pasture when the
disease develops. There are two reasons for this.
For these reasons, horses that have developed laminitis from pasture or that have
been diagnosed with IR should be allowed limited to no grazing. Horses with IR should
also not have sweet feed, treats with sugar, or anything with molasses in it. An
appropriate diet for a horse prone to laminitis from sugar is grass or alfalfa hay
and a ration balancer or multi-vitamin/mineral instead of grain.
- Certain grasses under certain conditions have high levels of fructans,
a specific sugar that has been shown to cause laminitis.
- Horses with insulin resistance (IR), a component of Equine Metabolic
Syndrome, are predisposed to laminitis and pasture acts as a trigger factor.
Additional strategies are available. For example, research suggests supplementing
with essential fatty acids may prevent laminitis caused by pasture carbohydrate
overload. The prescription medication Thyro-L (levothyroxine) is currently being
investigated as a treatment for insulin resistance toward a defense against laminitis.
Certain nutrients—chromium, magnesium, cinnamon and others—have been shown to help
support healthy metabolic function and may also be useful.
Laminitis and Founder
By: Lydia F. Gray, DVM, MA
SmartPak Staff Veterinarian and Medical Director