Explaining Laminitis
and Founder
Part Three
Diagnosis
Current Advice on Treating Laminitis
Prevention
Diagnosis
The first thing that you should do if you suspect laminitis is to call
your equine veterinarian. Laminitis should be treated as a medical
emergency, and prompt attention can improve the eventual outcome. The
severity of clinical signs is directly correlated to the severity of the
condition and your vet will do a thorough physical examination to
determine exactly how severely the horse is affected.
X-rays
The vet will want to take x-rays to measure the severity of any movement
of the pedal bone. Each case of laminitis is specific and the treatment
options are wide depending on the particulars of each case. Rotation can
continue to occur for weeks after the initial attack. It is recommended by
veterinarians specializing in equine podiatry that new x-rays be taken
every 5-10 days following an attack until the full extent of the damage is
played out to ensure that treatment takes into account the picture inside
the hoof during recovery rather than relying on a ‘snapshot’ taken at the
onset.
‘It is recommended
that new x-rays be taken every 5-10 days following an attack until the
full extent of the damage is played out’
Venogram
A relatively new technique, used extensively in the US by Dr. Ric
Redden, is the venogram. Dr. Redden is founder of the International Equine
Podiatry Centre in Versailles, Kentucky and a respected researcher and
gatherer of knowledge in the field of laminitis and foot care. The
venogram involves injecting a liquid into the digital vein that shows up
on X-rays. This liquid quickly fills the delicate veins and capillaries of
the foot, and when X-rays are taken, highlights the areas where
circulation is compressed or dilated and allows the veterinarian to more
accurately pinpoint the sites of major damage. This technique may also
have some therapeutic benefits, as Redden has noted that following the
procedure, there is a marked improvement and reduced pain. Venograms may
not yet be readily available in Australia except through veterinarians who
deal with lots of laminitis cases.
Current Advice on Treating Laminitis
With so many theories concerning the cause of laminitis, it is inevitable
that there are a number of theories concerning the correct treatment. We
have not yet found a cure for laminitis, to do so would be to preempt the
attack. At present we are dealing with the after effects of a catastrophic
chain of events that we seemingly have little control over, and no means
of detecting until it is too late. The predisposing condition that has led
to the laminitis is usually treated as the primary concern, with the
danger of laminitis only realized once foot pain is evident. For each
individual case, there will likely be an individual treatment plan, and
this can be very dependant on the experience and knowledge of your vet and
farrier. Veterinarians and farriers must work very closely together in
order to give the best treatment and pain relief for the horse. There are
a number of possible steps that may be taken depending on the specifics of
the case and any pre existing foot or limb conformation abnormalities.Â
Remove CauseÂ
Obviously the first thing to do with a laminitis case is remove the
cause of the problem. In the case of grain overload or grass founder, you
will need to make changes to the diet. Move the horse or pony to a paddock
with very little or no feed (but avoid over stressed pastures which may be
high in fructan), remove grain from the diet and feed only hay and water
as an immediate step. Lucerne (other than prime green) is ok to feed,
having relatively low carbohydrate content and low fructan levels, but do
not over-feed any kind of hay in the initial stages. A grassy lucerne/
clover is best, providing quality protein to help rebuild weakened hoof
horn.
‘In the case of grain
overload or grass founder, you will need to make changes to the diet’
Good quality meadow or grass hay is good,
or a cereal hay (oaten, barley) as long as it doesn’t have too much grain
attached. Due to the risk of some hays having high fructan levels (up to
30% in some cases) and because you can’t tell just by looking at it, it is
wise to soak the hay to reduce the level of water soluble fructan, and
feed only small amounts at frequent intervals, perhaps from a double
haynet to slow consumption rate as the horse picks the hay through the
holes. If a hard feed is required after the initial attack to maintain
condition, then concentrating on ingredients that are high in fat and
digestible fiber is recommended. Seek assistance from an equine
nutritionist if you have any doubts about what to feed. For the longer
term, you may be able to reintroduce limited pasture and should
concentrate on providing a balanced diet to meet all requirements for
protein, energy and minerals with limited carbohydrate intake. In those
cases caused by factors other than diet, the aim is to treat the initial
condition first, but if laminitis is recognized as a risk, the above steps
of changing diet in anticipation will be beneficial.
Pain Relief
As an immediate pain killer, Phenylbutazone (Bute) is the primary drug
recommended by the majority of laminitis specialists. Of course, pain
killers will do little to treat the condition, and by alleviating the
symptoms may encourage the horse to move more than it should, thus causing
further damage. Pain control must be carefully administered whilst the
horse is restrained in a well bedded stall to prevent excessive activity.
NSAID’s such as bute also serve to help alleviate the pressure and
inflammation in the foot. When using bute for extended periods, be aware
of the negative effects on gastric health and the possible threat of
gastric ulcers. Administering an equine antacid supplement such as
Neigh-Lox concurrently with NSAID medication may help to protect the
lining of the stomach whilst the pain killers are being used.
Moderating Circulatory Changes
There is a certain degree of controversy regarding the way that we should
be treating the foot in the developmental stages of laminitis. Whilst some
researchers focus on trying to increase circulation in the foot, others
believe that reducing circulation is the best way to manage and control
the damage.
Cryotherapy - Reducing blood flow
(constricting blood vessels)
Dr. Chris Pollitt and his research partner Dr Andrew van Eps have now
successfully shown that applying an ice slurry to the feet for extended
periods during the developmental stage prevents laminitis by constricting
major blood vessels and reducing the delivery of the blood borne trigger
factors to inner hoof wall lamellae. Damage to the basement membrane is
reduced and the lamellae remain attached. In tests performed in horses
that had been induced with laminitis, Pollitt found that application of an
ice slurry to one of the front limbs dramatically affected the circulatory
system in the foot. Capillaries and veins were successfully constricted,
with no apparent discomfort to the horse. No horse that had cold applied
to its hoof and fetlock developed clinical laminitis in that foot, whilst
the opposite limb had varying degrees of clinically significant changes.
This method also seemed to reduce some of the pain in the treated foot.
The problem for horse owners in the real world lies in recognizing the
horse in the developmental stages of laminitis, as there are usually few
outward signs until the majority of the damage has been done.
Drugs - Increasing blood flow
(dilating blood vessels)
In contrast to Pollitt’s theory, many respected experts on the subject
still believe that lamellar tearing and founder is the result of reduced
circulation to the lamellae, caused by the build up of fluid and pressure
as the basement membrane is damaged. The pressure of extra fluid in the
foot closes the capillaries which supply the lamellae, thus starving them
of nutrients and oxygen, and resulting in severe pain and further cellular
damage to the basement membrane. If this is case, the theory states that
further reducing circulation in a vasoconstricted foot may have dire
consequences. For proponents of this belief, stimulating vasodilation and
increasing blood flow is the recommended course of action. To that end,
certain vasodilating drugs are used including: Acepromazine, isoxuprine,
pentophyline and nitroglycerin.
The Dilemma – Constrict or Dilate?
The initial results of Adaire’s work on circulation patterns in the feet
of laminitis horses show that circulation is erratic during the
developmental stages of laminitis Early results of his studies show an
immediate decrease, followed by an increase in circulation that plateaus
at around 4-6 hours and lasts until the 10-12th hour, before decreasing
again just as symptoms are noticed. Recommended treatment options may
incorporate elements of both constriction and dilation at certain
‘windows’ following the laminitis trigger event. Certainly in the
developmental stages, current research strongly supports the cryotherapy
approach, but then at what stage would it be beneficial to introduce blood
vessel dilation methods if at all? It is likely that once we know more
about circulatory changes in different types of laminitis, we will
establish a rough guide to the windows of opportunity in which to apply
cold or drugs to modify circulation in the foot. It could well be that the
windows in which we should be trying to manipulate circulation occupy
different time periods following laminitis caused by grain overload or
pasture, and different again for laminitis caused by other disturbances.
Results of ongoing research can only help us to understand the way in
which we should be treating the feet of horses suffering this painful
condition in order to limit or prevent further damage.
Exercise Vs Stall Rest
Again, controversy abounds in the argument for exercising horses with
laminitis. In the acute stages, most owners will box the horse with deep
soft bedding to help relieve the pressure on the pedal bone, help the
horse find a comfortable position and prevent further damage that may be
caused by walking around. Light hand walking exercise has been previously
recommended for horses once the immediate pain of the acute stage has
subsided, to assist in stimulating circulation. As previously described,
it is not yet known whether stimulating circulation is desirable, or
exactly when we should try to stimulate. One thing is for sure, walking
too much and especially forcing movement during the developmental and
acute stages of the condition may adversely affect laminar separation and
pedal rotation. Do not force a horse to walk if it is clearly in pain and
reluctant to move.
Venogram
As previously mentioned, a venogram is commonly performed in the US to
assist with diagnosis, but practitioners have noted that the horse seems
to be in less pain following the procedure, indicating that it may have
therapeutic applications. These benefits are thought to lie in the fact
that the procedure seems to open up blood vessels and improve circulation
to constricted sites, reducing the pain associated with the crushing of
these vessels. – Another ‘fly in the ointment’ in the constrict or dilate
debate!
Therapeutic Shoeing
Expert farriery can mean the difference between a horse making a full
recovery or being unable to return to his previous level of work. The
assistance of a good farrier preferably with experience in dealing with
laminitis cases will be invaluable to horse owners who find themselves
dealing with the condition. Mechanical assistance is almost always
recommended, but the degree and type of assistance depends on the
individual case, its severity and the conformation of the limbs and feet
to begin with. Many farriers feel that supporting the frog is of immediate
concern as soon as symptoms are noticed. Support can be given by padding
up around the frog with gauze bandages or a commercially available ‘lily
pad’ which can be fitted whilst a horse is still wearing shoes. Immediate
pain relief can be offered by using a wedge to raise the heel, thus
relieving pressure from the toe area. Raising the heel reduces the pull on
the rear of the pedal bone and may help to minimize further lamellar
tearing. Remedial shoeing is not recommended until the horse is
comfortable, and the acute stage is over (i.e. usually after the first 48
hours). Holding up the feet for extended periods of time in a horse that
is still undergoing changes, may exacerbate the condition and cause undue
discomfort. For this reason, whilst the acute stage plays out, it is often
best to keep the horse in the condition that it was before the attack,
i.e. if it was wearing shoes, leave them on, if it was barefoot, leave it
barefoot in a well bedded stall.
‘Expert farriery can
mean the difference between a horse making a full recovery or being unable
to return to his previous level of work’
Once the pedal bone has become stable and
is no longer moving according to radiographic evidence, the true road to
recovery can begin. In mild cases, simply trimming the hooves to lower the
heels and rasping the toe to improve breakover and to realign the pedal
bone in a straight line with the pastern bone may be all that is required.
If your farrier and vet decide on remedial shoeing, there are a number of
choices depending on the particular horse. All are designed to support the
heels, relieve pressure at the toe and support the sole. Designs currently
used include the egg-bar, the heart bar and the adjustable heart-bar. Some
farriers prefer aluminium shoes which are light weight and need only small
nails to hold them on, others advocate glue-on shoes to remove the need to
pound on the feet at all. Many will use shoes with a rolled toe, or will
cut back the toe in an effort to improve break-over. Most of these shoes
will incorporate some kind of padding to support the frog and or sole.
This is thought to help relieve pressure on the hoof wall and directly
supports the pedal bone. Only the back half of the sole should be
supported, as pressure directly beneath the descending tip of the pedal
bone will only worsen the situation. The act of raising or lowering the
heels is one of considerable debate, but most farriers agree that shoes
with rolled toes – to bring the point of break-over as far back as
possible (close to the tip of the pedal bone) is of benefit.
Tenotomy
Tenotomy may be suggested in severe cases of founder to reduce load on the
digital flexor tendon, and in cases where the pull of the tendon has a
major influence on pedal rotation. Cutting the deep digital flexor tendon
offers immediate relief in those cases where the pedal bone has rotated
downward in response to the strong pull of the tendon. The act of cutting
the deep digital flexor tendon is not a decision to be taken lightly, and
would usually only be considered in those cases where euthanasia is the
only other option available. Trials evaluating this treatment method have
shown a better quality of life for serious chronic cases. The procedure
may extend the life of these horses, though the cost and effort involved
in aftercare should be taken into account. The procedure itself is done
under local anesthetic and so is relatively inexpensive, but aftercare
involving regular corrective trimming can drive the cost up. The tendon
heals with scar tissue forming within two to four months, and the area
becomes thickened accordingly. Most horses assume at least pasture
soundness following the procedure, with some able to perform light work
within eight months to a year of treatment. Some horse have reportedly
retuned to full competitive work following tenotomy.
MMP Inhibitors
With the work of Dr. Chris Pollitt on laminitis trigger factors and the
current evidence supporting the MMP enzyme theory of basement membrane
failure, attention is directed towards halting the cascade of devastation
at the cellular level. Various substances have been show experimentally to
inhibit the activity of the MMP enzymes. Current research is focusing on
the possibility of using manufactured inhibitors to block further MMP
degradation of the basement membrane within the foot of an affected horse
during the developmental and acute stages of the condition.
Assisting in The Road to Recovery
If you have been lucky enough to catch the condition early, and judicious
treatment by vet and farrier have paid off, you may be well on your way to
a full or at least partial recovery within just a few months. As the
hooves start to recover from the ordeal of laminitis, you will notice some
irregularities in the hoof wall re-growth. After an attack, hoof wall can
grow sporadically, sometimes growing very fast, and then very slowly,
forming ridges and lines as the lamellae beneath become reorganized. To
help grow out healthy hoof, you can include a hoof supplement in the diet.
A supplement containing biotin, zinc and methionine will ensure good
quality horn in the re-growth and may help to grow out the irregular horn
more quickly. Of course, whilst the horse is recovering, and even after
everything possible has been done to assist with a return to previous work
levels, you must take care to prevent a recurrence. Once a horse has
suffered laminitis, it is more likely to suffer a recurrence. If there has
been pedal bone rotation, then you will be especially eager to prevent
further damage that could permanently incapacitate the horse.
Prevention
Prevention is always better than cure. Designing a diet to prevent
laminitis reoccurring is similar to designing a diet that you would feed
during recovery, but with just a little more leeway. The key is to
anticipate and be aware of the danger signs.
• Don’t allow unrestricted access to lush pasture, use a muzzle or
temporary fencing to strip graze and restrict access with some stall or
dry yard time each day.
• Soak hay to reduce sugar content and avoid using extremely rich forage
sources.
• Beware of grazing stressed short grass and do not turn out onto frosted
pastures or drought recovering pastures because of the danger of high
fructan levels.
• It may be sensible to graze pastures only after dark and in the early
morning when fructan levels are lower.
• Do not feed a diet that is high in starch (i.e. grain). Instead, try to
formulate a balanced diet that is high in fat and fibre, with minimal
reliance on grain and carbohydrate rich pasture for weight maintenance.
• Avoid letting your horse or pony get too overweight, this can increase
the risk of laminitis. Laminitis is more common in certain breeds, but
this is usually related to those breeds being particularly prone to being
overweight.
• Use a quality vitamin and mineral supplement to balance the deficiencies
of hay.
• Beware of the dangers of retained placenta if you have a mare in foal,
and if your horse gets severely sick for any reason think laminitis, and
call your vet’s attention to the fact that your horse is a previous
sufferer.
• Minimise stress. Stress causes the release of corticosteroids, which
have been implicated as a cause of laminitis.
• Beware of hard ground in the dry months, and take it easy on your horses
feet.
• You may want to continue feeding a hoof supplement to ensure that your
horses feet are as structurally sound as they can be.
Products containing virginiamycin, a
bacterial product of Streptomyces virginiae, can reputedly prevent the
population explosion of gram-positive bacteria including Streptococcus
bovis and Lactobacillus spp. following the ingestion of a large
carbohydrate rich meal (lush grass or grain). Though it is no substitute
for good management practices, these supplements may help in allowing a
susceptible horse live a next to normal life and may help particularly
sensitive animals enjoy at least limited access to pasture. Virginiamycin
is not recommended for mares in foal or stallions at stud. Virginiamycin
containing products are now only available as a prescription medication in
Australia due to concerns about antibiotic resistance through its
prolonged use.
Preventing laminitis is about pre-empting
its development. Once you have been unfortunate enough to experience it,
you become much more aware of your horses attitude and watch for signs
constantly, especially in the high risk periods. The moment you notice
that something is amiss, call the vet and get prepared, you may be
worrying over nothing, but with laminitis, it’s best to be safe than
sorry.
Article reproduced courtesy
of Kentucky Equine
Research
Part One
Introduction
Anatomy of the Horses FootÂ
What Happens When a Horse Suffers a Laminitis Attack?
Part Two
What Causes Laminitis?
Symptoms Â
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