Founder & Laminitis
Robert N. Oglesby, DVM

Despite intensive investigation, founder is still a poorly
understood disease. Though easy to diagnose and usually
treatable, this disease has the potential to result in permanent
severe lameness making euthanasia the most humane option.

SYMPTOMS
The signs of founder are easy to recognize: they are the result
of both front feet being sore. The back feet may be involved too,
but the front feet bear 50% more weight than the rear so they
usually hurt more. With both feet being sore the horse's steps
shorten and become slower making the horse or pony look stiff. At
rest he will prop his front feet out in front of him while
leaning back on his rear legs to help decrease the weight on the
front. Frequently, he will shift weight back and forth from one
front foot to the other. As the pain worsens he may start
spending a lot of time laying down.

This article concerns itself with cause, diagnosis, treatment and
prognosis.

WHY IT HAPPENS
The Hammock
Founder is a disease of the laminae of the foot. To understand
founder you must understand what the laminae are. As weight is
transferred down the leg to the foot it does not get transferred
directly down through the bottom of the sole. The foot (coffin)
bone is suspended from the hoof wall by the laminae. The result
is, weight transfers to the walls of the hoof, then down the
walls to the ground. This puts weight bearing on the toughest
structure, the wall, and helps reduce concussion on the
relatively sensitive sole. To help see this relationship think of
a man in a hammock. The man represents the toe bone and the
weight of the horse on that leg. The hammock and ropes represents
the laminae. The trees, to which it is tied, is the hoof wall.
The tree supports the whole weight of the man by way of the
hammock.

The Broken Hammock
When a horse develops founder, the hammock (laminae) begins to
weaken and fray. When the founder is severe, the hammock
(laminae) breaks, dumping the man (toe bone) onto the ground. In
severe founder, the toe bone comes through the sole on the bottom
of the hoof.

Why Does The Hammock Break: Inflammation vs. Ischemia For a long
time acute founder was thought to be a disease caused by
inflammation and was dubbed laminitis (-itis means inflamed). It
is easy to see why: Heat, swelling and pain were present and
these are all signs of inflammation. On closer study, several
problems with the inflammation idea surfaced. It was often hard
to understand what caused the inflammation. There was the problem
that inflammatory cells, an important mediator of inflammation,
were missing during the acute phase of the founder. Something
else appeared to be going on.

Several researchers developed an alternate theory: founder
results from too little oxygen getting to the hard working
laminae. This was hard to accept because the increased heat and
pulse seems to suggest increased blood flow. They had an
explanation: the presence of blood vessels that shunt the blood
away from the laminae. The purpose of these shunts in a healthy
horse is to keep the horse's foot warm in very cold weather by
allowing increased blood flow. During founder they
inappropriately open and route blood away from the laminae.
Tissue becomes damaged and inflammation follows to help fight
infection and remove damaged tissue. The theory has gained
support in the last several years and the shunts have been
identified with electron microscopy.

Recent research suggests that an important component may be
platlet aggregation which forms thrombi (clots) and routs the
blood away from the lammelar capillaries resulting in ischemia
(AJVR, v 58, n 12, pg 1376).

ACUTE VS. CHRONIC
There are two recognizable forms of founder. In the acute form
the disease comes on suddenly and the severity can vary depending
on the size of the insult to the laminae. Some lameness experts
believe that in the acute form, most of the damage is done in the
initial few hours of the disease.

The chronic form of founder affects ponies and overweight horses
on rapidly growing pasture or too much concentrate. This form of
the disease is a recurring problem whenever the horse or pony is
allowed to get overweight, eat rich foods, or his feet are
allowed to get too long. Damage done during the flare up is
usually not as severe as seen in acute attacks but over time the
damage can build up. Usually the flare ups are preventable with
good management.

Whenever an acute case of founder occurs, radiographs are vital
to keep up with changes in the foot. Radiographs can monitor
rotation of the toe bone within the hoof capsule that correlates
to the amount of damage done to the laminae. It may be that you
will be watching changes over which you have little control, but
rate and degree of change will be your best prognostic guide.

SOME CAUSES
We know some of the causes of founder, but some cases are hard to
explain. Listed below are some of the common causes of acute
founder:

1. Horse getting into the feed bin and eating too much grain
2. Gram negative bacterial infections with endotoxemia
3. Excessive concussion to the feet
4. Obesity
5. Standing on black walnut shavings
6. A hot horse drinking too much cold water too fast

TREATMENT
First Aid
Acute founder is always an emergency requiring professional help
to minimize permanent damage. First aid measures include:

1.Call the veterinarian. While waiting; attempt to get your horse
to walk. This helps to increase circulation and relieve some of
the pain. Walk him on very soft ground. If he refuses to walk
with gentle encouragement do not force him, as this may do
further damage.

Walking foundered horses has become controversial with some
insisting that it does further damage. I have seen dozens of mild
founders respond well to walking on soft ground. If the horse
does not want to walk after gentle encouragement (a light whip),
do not force him is a good rule of thumb.

2.If veterinary help is not immediately available give bute (2
gm./1000 lbs twice daily) or aspirin.

Medication
There are currently dozens of treatment regimens suggested for
the treatment of founder, many whose theories conflict with each
other. Except for the nonsteroidal antiinflammatory drug (NSAID)
phenylbutazone (bute) no single treatment has been shown to be
more efficacious than another. It seems that in some cases what
worked last time doesn't this time and what didn't work before,
does this time. I think that frequently outcome is based on the
amount of damage done on the first day and not the treatment
selected. Keeping the horse as comfortable as possible requires
experienced help.

Some recommend the more expensive NSAID's like Banamine (1) and
Arquel (2) over the cheaper bute. There is no evidence that these
drugs relieve the pain of founder better than bute as response to
pain relievers is frequently dose dependent: the more you give
the better the pain relief . . . to a point. Bute has one big
advantage in that we have a better idea of how much can be given
for how long and with what effects. The exception would be if
endotoxins are playing an important role in the case. Banamine
has been shown to block some effects of endotoxins on tissues.
The Banamine should be substituted for the bute initially. Dosage
for endotoxin blocking effects is poorly defined and it is best
to stay with the upper end of manufacturer recommendations. Bute
and Banamine have been used together, but no studies are
available on side effects.

Trimming and Shoes
There have been many shoeing recommendations for acutely
foundered horses and few are better than no shoes and soft
footing, some are considerably worse. The exception may be the
horse with poor quality sole and hoof wall. If these horses
cannot be kept acceptably comfortable without shoes you can try:

1. reversed shoes
2. egg bar shoes
3. heart bar shoes
4. any of the above with pads or pads taped on alone Which may
help in your case is determined by which does the best job of
relieving pressure at the toe and it's associated sole.

Soaking The Feet
A frequently recommended treatment is soaking the feet in water.
Traditionally, cold water was used and I think some pain relief
occurs when a horse has soaked in cold water. It has been pointed
out that cold usually restricts blood flow and warm soaks have
been suggested as better. I no longer soak feet for acute founder
and have not noticed a change in the expected outcome. Hooves
that are developing abscesses secondary to their founder need to
have the abscesses opened, drained, and soaked in antiseptics.

Summary of Treatment
It is still hard to beat for treatment:

1. IV bute for pain. The dose is adjusted to affect.
2. Remove the horse's shoes and roll the toes if there is good
sole support from the rest of the wall of the hoof. You want the
sole concave with respect to the ground. The toe and it's
associated sole should be off the ground.
DO NOT do any trimming on a horse with poor walls and thin soles.
These horses need all the support they can get. Horses in this
category may require special attention and procedures.
3. Place the horse in a large stall or small paddock with very
soft footing.
4. If grain overload is involved, several doses of mineral oil
given by stomach tube and Banamine as quickly as possible are
very important.
5. Low dose acepromazine (.02 mg/kg 4x daily) to increase blood
flow.

PROGNOSIS
A poor chance of recovery should be considered whenever:

1. Rotation continues despite treatment.
2. Rotation exceeds 12 degrees. Less than 6 degrees is important
if a return to athletic endeavors is hoped for.
2. The coffin bone sinks away from the wall at the level of the
coronet.
3. Pain prevents a horse from rising.
In the case of remarkable pain and little rotation, there is
always hope, but some of these horses will be very slow to
recover. They may require several months of care and medication.

SEVERE, UNRESPONSIVE FOUNDER
If the horse is having marked pain, but rotation is not
remarkable, consider the possibility of sole abscesses as the
cause. Usually abscesses arise unilaterally, so you first notice
one foot much worse than another, but abscesses may follow
rapidly in the other foot. Any suspiciously painful areas in the
sole should be explored.

Dr Redding of the Equine Podiatry Center in Lexington KY has
recommended for several years that when faced with remarkable
rotation, elevation of the heels 12 to 15 degrees to be
beneficial. Three # 4 pads nailed together is about right. He has
seen cases quit rotating when treated this way. The hypothesis is
that elevating the heels reduces the forces on the coffin bone
that result in rotation, the pull of the DDF tendon.

The theory of relieving pull on the toe bone by the deep digital
flexor (DDF) is sound on paper and in practice. DDF tenotomy has
been used for many years as a salvage procedure to help badly
foundered horses. Anyone interested in this procedure should
contact the Podiatry Center for the latest developments.

Occasionally despite your best efforts, the horse remains very
painful and rotation of the toe bone continues. If radiographs
show severe rotation occurring rapidly, or sinking to any degree,
the chance of recovery to even pasture soundness is poor.
Prolonged treatment and expense, while the horse suffers,
benefits no one.