rib margin through the flank the muscles will thicken if
the condition is chronic causing what is called “heaves
line” to be seen.
Bacterial, parasitic and viral infections can all be
responsible for this inflammatory airway disease in horses.
Allergies might be a factor including the common allergies
to grains, grasses, tree pollens, flowers or airborne
pollutants and chemicals. Changes in the passageways can
result if repeated inflammation occurs and this is often not
There is a thickening of the muscular and fibrous tissues
that line the large airways of the lungs in horses with
heaves. Excessive mucus is often produced by affected
horses. The size of the airway is a result of this
combination which can make it hard for the horse to breathe.
The problem is already severe once the horse has difficulty
breathing so this is why prevention and early diagnosis is
very important. However, it can be difficult to obtain early
diagnosis. Samples of fluid and mucus from the large airways
of the lungs can be tested and analyzed with a bronchio-alveolar
lavage in suspected horses.
The large lung airways are bronchi while the smaller airways
are alveoli. A tube is placed into the horse’s trachea or
windpipe during the test and then passed into the deeper
airways of the lung. A sterile saline solution is then
flushed through the tube and into the horse’s lungs. The
solution is then collected by being drawn back out of the
airways. The sample is then analyzed for both bacteria and
cell types that can indicate the start of an allergic
While there is no specific number of cells that can show the
start of heaves the test can help point out potential
problems. Human methods of testing have been tried for
horses with heaves for diagnosis and evaluation since heaves
closely resembles emphysema in humans. For example, the
force produced by breathing is tested with respirometry.
This is when the humans blow into a special device that
measure the force of their exhalation. Horses require a
special device that covers their nostrils to record their
breathing efforts since they are nose breathers.
Horses can be identified by score significantly lower that
normal on these tests and in this manner some early cases of
heaves can be diagnosed. This is especially so when the
respirometry measurements are combined with the bronchio-alveolar
lavage cellular results.
Avoiding allergies and environmental toxins that might cause
heaves is the best method of prevention. Progress has been
made by researchers in the manner of learning what to avoid
and how to manage horses with the problem better. Throughout
a normal day the dust around a horse’s nose is often three
times higher than the dust around factories according to a
recent Michigan State University test.
The biggest culprits are hay and poor-quality processed
grains. It is especially risky if you have hay that has been
poorly cured or old hay. It is best that you open a bale of
hay and shake out a flake or two first. If you find mold or
dust or have several of the flakes sticking together then it
may cause your horse respiratory problems.
On occasion horses can tolerate such irritants but
susceptible horses will develop heaves if they face
continual exposure. It is still a long way off before we
will have the ability to detect which horses will develop
heaves even though testing is starting to become more
helpful. Prevention and treatment should remain the focus of
One obvious help is by using good-quality hay and grain.
Always consider where the dust is coming from. If possible
you should avoid storing hay over the stalls. You can help
reduce some dust by wetting the hay prior to feeding. Heavey
horses should be fed from the ground instead of a wall
feeder. Wall feeders keep the dust and hay near a horse’s
nose while hay on the ground allows the horses to avoid the
dust and get the added benefit of gravity which keeps the
majority of the dust particles out of their lungs.
Feeding with hay cubes, pellets and complete feeds can help
reduce the dust for the horses that already have airway
diseases. It is also important to pay attention to air
circulation in barns, you should make sure they are kept
open and that the dust is reduced to a minimum. Another
option to consider is replacing dusty shavings with shredded
paper bedding. The best management you can use is to keep
horses outside in the fresh air as much as possible.
There are two phases to approach in the treatment of heaves.
Drugs called bronchodilators are usually used for immediate
relief in horses with heaves. These products allow the
smooth muscles in the lung airways to relax. Almost
immediately this makes breathing easier for horses although
it doesn’t have any curative effect on the process of the
disease. Recently the FDA gave approval to use clenbuterol
as a potent bronchodilator for horses. To animals suffering
from COPD this drug can provide substantial benefits.
However, there are strict rules set up by the FDA that are
used for its sale and use.
For horses there is a new face mask that is used to allow
them to breathe in a mist of drugs from an inhaler. Despite
the fact that the mask look uncomfortable and not easily
tolerable by horses it actually provides them immediate
relief and horses will quickly learn to accept the mask and
the blast of medication from the inhaler.
However, these drugs are not used for long-term use. Rather
corticosteroids are used for maintenance treatment. It will
take a few days to a week or so for the steroidal
anti-inflammatory drugs of NSAIDs to take effect and the
results can vary between the horses.
Allergic diseases are highly individualistic which means
that each horse needs to have the exact type of drug,
dosage, method of administration and dose frequency worked
out for them.
In certain cases homeopathic remedies can be helpful.
Knowing just what your horse is allergic to can be helpful
since the disease is allergic in nature. There are new test
available to determine a horses allergies.
While specific offensive can not always be eliminated from
the horses world, knowing what to avoid can help a lot. Good
management to have a reduction of dust, mold and other
environmental irritants added to this can help slow heaves
or prevent it from happening completely.