Preventing Laminitis - Dr Jennifer Stewart

Preventing laminitis in horses 99
(ie, those that grow well in the southern states) tend not to
store fructans as do grasses from more temperate or colder
areas. They can, however, be high in starch and other NSCs
under the right conditions, so they too are a potential laminitis
risk. Tall fescue may present an additional risk if it is
infested with a common endophytic fungus (Neotyphodium
coenophialum). Endophyte-infested fescue has been shown to
increase the risk for laminitis in both horses and cattle.
Grazing Management
Preventing pasture-associated laminitis begins with accurately
assessing each horse’s laminitis risk and managing its
pasture access accordingly. In horses that have had laminitis
in the past, particularly pasture-associated laminitis, and in
those that are overweight, it is best to avoid any grazing of
improved pastures during periods in which the fructan content
is likely to be high. Limited access to native or unimproved
pastures may be less problematic in these horses.
Intake of fructans and other NSCs during high-risk periods
can be limited in a number of ways, depending on the
particular horse’s laminitis risk and on the type and condition
of the pasture:
● limit the amount of time a horse is turned out on pasture
each day (from 30 minutes to several hours, depending
on the risk)
● allow grazing only during relatively low-risk times of the
day (eg, late at night, early morning)
● limit the size of the available pasture by using moveable
fences to create small paddocks (Note: avoid overgrazing)
● use a grazing muzzle which limits the amount of grass
the horse can eat while turned out.
Daily activity is very important for the health and wellbeing
of every horse, but particularly for those that are overweight.
When pasture turnout must be limited or prevented
altogether, the horse should be turned out into a dry lot (ie, a
grassless area) to allow several hours of activity every day.
Inactivity increases a horse’s laminitis risk, especially when
combined with excess body weight.
There are several forage testing laboratories that will test
pasture samples and report on the levels of NSC or NFC in
the grass. When performed periodically throughout the year,
this approach may assist owners or farm managers in identifying
the periods when their pastures are at greatest risk.
However, it is by no means foolproof, as environmental conditions
during any given month can change dramatically
from year to year, even from day to day. Measurement of
NSCs in hay, though, can be very useful in determining
whether a particular batch of hay is suitable for laminitisprone
horses (see below).
Feeding Grain
There are two general scenarios in which grain feeding can
cause laminitis or significantly increase the potential for it to
occur: (1) grain overload and (2) feeding grain to an overweight
horse. The classic example of grain overload is of a
horse that gets into the grain bin and gorges on several
pounds of grain at once. The sequence of events leading to
laminitis are similar to those of pasture-associated laminitis.
The starch in grain can be broken down by enzymes in the
small intestine and absorbed before it reaches the large intestine.
However, with a large grain meal, the amount of starch
consumed by the horse exceeds the ability of the small intestine
to digest and absorb it all, so some of the starch spills
over into the large intestine. Starch is readily fermented by
the microbes in the large intestine, with potentially the same
consequences as those described for fructans.
This problem doesn’t just occur with whole grain; it can
occur with any grain-based feed—ie, any feed in which any
type of grain forms the principle ingredient(s), regardless of
whether or how it is processed. For the average sized horse, it
usually takes at least 5 lbs of starch in one meal to cause
spillover into the large intestine; in small ponies or Miniature
Horses it may take only a pound or two. However, spillover
of starch into the large intestine doesn’t always lead to laminitis;
it depends on how much starch reaches the large intestine—the
greater the starch intake, the greater the laminitis
risk.
Preventing Laminitis
Caused by Grain Overload
Grain overload is a medical emergency. The horse may not
show signs of laminitis for up to 48 hours after overindulging
in grain, by which time it is too late to prevent the damage.
Preventing laminitis in this situation involves calling the veterinarian
immediately it is discovered that the horse has consumed
an excess of grain. Disaster can often be averted by
administering mineral oil or activated charcoal by stomach
tube, if done early enough. Cold therapy (standing the horse
in ice water until 48 hours have passed since it consumed the
grain) may also be an effective means of preventing severe
laminitis in this situation, and well worth the time and effort
it takes.
Preventing this situation in the first place is simply a matter
of being aware of the risk and preventing unlimited access to
grain. Grain storage areas should be secured with a system
that has a built-in back-up (eg, a lockable latch on the feed
room door and latches or bungee cords on the feed bin lids).
Simply making a habit of keeping the feed room door securely
closed, and impressing on everyone who uses the area
to do the same, can prevent a tragedy.
Less commonly, other high-carbohydrate feedstuffs can
cause laminitis when fed in excess. These items include
bread, other bakery products or byproducts, sweet fruits
such as apples and water melons, and lawn clippings. These
feedstuffs are more likely to be fed in large amounts by new
horse owners or well-meaning neighbors who are unfamiliar
with horse management. Preventing laminitis caused by
these feeds is simply a matter of limiting their intake to only
the occasional treat, although lawn clippings should never be
fed to horses.
Overfeeding and High-Grain Diets
The second scenario in which grain feeding can increase a
horse’s laminitis risk is all too common: feeding grain to
horses that don’t need the extra calories and, as a result, are
overweight. This problem is discussed further in the next
section on weight management.