Every day veterinarians
across the country see hundreds of cases of laminitis, a painful
disease that affects the horse's feet. What is especially alarming
is that some cases are preventable. In fact, it may be that we are
killing our horses with kindness.
Consider that a common
cause of laminitis is overfeeding -- a management factor that is
normally within our control.
By learning more about
laminitis and its causes, signs and treatments, you may be able to
minimize the risks of laminitis in your horse or control the
long-term damage if it does occur.
LAMINITIS DEFINED
Laminitis results from
the disruption (constant, intermittent or short-term) of blood flow
to the sensitive and insensitive laminae. These laminae structures
within the foot secure the coffin bone (the wedge-shaped bone within
the foot) to the hoof wall. Inflammation often permanently weakens
the laminae and interferes with the wall/bone bond. In severe cases,
the bone and the hoof wall can separate. In these situations, the
coffin bone may rotate within the foot, be displaced downward
("sink") and eventually penetrate the sole. Laminitis can affect one
or all feet, but it is most often seen in the front feet
concurrently.
The
terms "laminitis" and "founder" are used interchangeably. However,
founder usually refers to a chronic (long-term) condition associated
with rotation of the coffin bone, whereas acute laminitis refers to
symptoms associated with a sudden initial attack, including pain and
inflammation of the laminae.
CAUSES
While the exact
mechanisms by which the feet are damaged remain a mystery, certain
precipitating events can produce laminitis. Although laminitis
occurs in the feet, the underlying cause is often a disturbance
elsewhere in the horse's body. The causes vary and may include the
following:
- Digestive upsets due to grain overload (such as excess
grain, fruit or snacks) or abrupt changes in diet.
- Sudden access to excessive amounts of lush forage before the
horse's system has had time to adapt; this type of laminitis is
known as "grass founder."
- Toxins released within the horse's system.
- High fever or illness; any illness that causes high fever or
serious metabolic disturbances has the potential to cause
laminitis, e.g., Potomac Horse Fever.
- Severe colic.
- Retained placenta in the mare after foaling.
- Excessive concussion to the feet, often referred to as "road
founder."
- Excessive weight-bearing on one leg due to injury of another
leg or any other alteration of the normal gait.
- Various primary foot diseases.
- Bedding that contains black walnut shavings.
- Prolonged use or high doses of corticosteroids.
RISK FACTORS
Factors
that seem to increase a horse's susceptibility to laminitis or
increase the severity of the condition when it does occur include
the following:
- Heavy breeds, such as draft horses
- Overweight body, cresty necks
- High nutritional plane (feeding large amounts of
carbohydrate-rich meals)
- Ponies, Morgans, miniature horses
and donkeys
- Unrestricted grain binges, such as when a horse breaks into
the feed room (if this happens, do not wait
until symptoms develop to call your veterinarian--
call immediately so corrective action can be taken before tissue
damage progresses)
- Horses who have had previous episodes of laminitis
- Older horses with Cushing's disease
SIGNS
Signs of acute
laminitis include the following:
- Lameness, especially when a horse is turning in circles;
shifting lameness when standing.
- Heat in the feet.
- Increased digital pulse in the feet (most easily palpable
over either sesamoid bone at the level of the fetlock).
- Pain in the toe region when pressure is applied with hoof
testers.
- Reluctant or hesitant gait ("walking on eggshells").
- A "sawhorse stance," with the front feet stretched out in
front to alleviate pressure on the toes and the hind feet
positioned under them to support the weight that their front
feet cannot.
Signs of chronic
laminitis may include the following:
- Rings in hoof wall that become wider as they are followed
from toe to heel.
- Bruised soles or "stone bruises."
- Widened white line, commonly called "seedy toe," with
occurrence of seromas (blood pockets) and/or abscesses.
- Dropped soles or flat feet.
- Thick, "cresty" neck.
- Dished hooves, which are the result of unequal rates of hoof
growth (the heels grow at a faster rate than the rest of the
hoof, resulting in an "Aladdin-slipper" appearance).
TREATMENT
The sooner treatment
begins, the better the chance for recovery. Treatment will depend on
specific circumstances but may include the following:
- Diagnosing and treating the primary problem (laminitis is
often due to a systemic or general problem elsewhere in the
horse's body).
- Dietary restrictions; stop feeding all grain-based feeds and
pasture. Feed only grass hay until advised by your veterinarian.
- Treating with mineral oil via a nasogastric tube to purge
the horse's digestive tract, especially if the horse has
overeaten.
- Administering fluids if the horse is ill or dehydrated.
- Administering other drugs such as antibiotics to fight
infection; anti-endotoxins to reduce bacterial toxicity; and
anticoagulants and vasodilators to reduce blood pressure while
improving blood flow to the feet (corticosteroids are
contraindicated in laminitis, as they can actually cause
laminitis or exacerbate existing cases).
- Stabling the horse on soft ground, such as in sand or
shavings (not black walnut) and encouraging the horse to lie
down to reduce pressure on the weakened laminae.
- Opening and draining any abscesses that may develop.
- Cooperation between your veterinarian and the farrier
(techniques that may be helpful include corrective trimming,
frog supports and therapeutic shoes or pads).
- Your veterinarian may be able to advise you on new therapies
that may include standing your horse in ice water to prevent the
onset of laminitis after a predisposing cause such as a retained
placenta or a known grain overload.
LONG-TERM OUTLOOK
Some horses that
develop laminitis make uneventful recoveries and go on to lead long,
useful lives. Unfortunately, others suffer such severe, irreparable
damage that they are, for humane reasons, euthanized.
Your equine
practitioner can provide you with information about your horse's
condition based on radiographs (X-rays) and the animal's response to
treatment. Radiographs will show how much rotation of the coffin
bone has occurred and may also illustrate abscesses or gas
accumulation that will affect the therapy of your horse.
This will help you make a decision in the best interest of the horse
and help the farrier with the therapeutic shoeing.
MANAGEMENT
It's important to note
that once a horse has had laminitis, it may be likely to recur. In
fact, a number of cases become chronic because the coffin bone has
rotated within the foot and the laminae never regain their original
strength. There may also be interference with normal blood flow to
the feet as well as metabolic changes within the horse. Extra care
is recommended for any horse that has had laminitis, including:
- A modified diet that provides adequate nutrition based on
high-quality forage, digestible fiber (beet pulp) and oil. Avoid
excess carbohydrates, especially from grain.
- Routine hoof care, including regular trimming and, in some
cases, therapeutic shoeing (additional radiographs may be needed
to monitor progress).
- A good health-maintenance schedule, including parasite
control and vaccinations, to reduce the horse's susceptibility
to illness or disease
- Possibly a nutritional supplement formulated to promote hoof
health (biotin supplements are popular for promoting hoof
growth).
- Avoid grazing lush pastures, especially between late morning
and late afternoon hours, since plant sugars are the highest
during these times. Restrict pasture intake during spring or
anytime the pasture suddenly greens up.
SUMMARY
The best way to deal
with laminitis is preventing the causes under your control. Keep all
grain stored securely out of the reach of horses. Introduce your
horse to lush pasture gradually. Be aware that when a horse is ill,
under stress or overweight, it is especially at risk. Consult your
equine practitioner to formulate a good dietary plan. Provide good,
routine health and hoof care. If you suspect laminitis, consider it
a medical emergency and notify your veterinarian immediately.
