Causes and diagnosis
Heaves is thought to be caused by chronic
exposure to dust, molds, or other air pollutants
and allergens. It can be triggered
by respiratory tract infections or increased
exposure to the above causes.
Diagnosis is often based on the clinical
signs of respiratory disease without evidence
of infection, fever, or acting sick.
In chronic cases, the abdominal muscles
become overdeveloped from breathing
efforts, causing a “heave line”.
A definitive diagnosis can be made
by cytology (looking at the cells present)
and culture (checking for bacterial
growth) of a transtracheal wash (TTW)
or bronchoalveolar lavage (BAL), both
of which are used to obtain fluid samples
from the horse’s lungs. When testing is
not possible, response to treatment can
also help determine a diagnosis.
Hint
Heaves can lead to clinical signs such
as exercise intolerance (easily winded),
expiratory dyspnea (difficulty exhaling),
chronic coughing or wheezing, nasal
discharge, and weight loss.
Treatment with
Western medicine
Environmental management is the first
line of defense against heaves, no matter
what approach you are taking.
Eliminating allergens, especially dust
and molds, can be done by:
• Switching to pelleted hay
• Soaking your horse’s hay before feeding
• Feeding pelleted grain
• Soaking the horse’s grain before feeding
• Keeping the horse outside 24/7 if possible
•If he must be stalled, using pelleted
shavings in a well ventilated stall
•Riding in dust free environments
Steroids are medications that reduce
airway inflammation. They are often
needed to control the clinical signs of
heaves and to keep the horse comfortable.
They are used for maintenance
therapy at as low a dose as possible,
often once a day or just seasonally or
during flare-ups.
Because steroids can have harmful long
term side effects, the route of administration
is important. Inhaled steroids
treat the condition locally and are used
at lower doses, which help minimize
negative side effects. Flovent (the human
inhaler, fluticasone) is the steroid of
choice, but others such as Beconase
(beclomethasone) or dexamethasone via
nebulizer can also be used. Inhaled steroids require the use of a special mask,
such as the Aeromask, which is often
quite expensive; a second option is the
Equine-Haler, which is bit less expensive.
However, the Aeromask rates higher in
drug disposition in the lungs, making it
a better choice long term.
If inhaled steroids are not an option,
oral or injectable steroids such as dexamethasone
or vetalog can be used.
Bronchodilators dilate or open the airways.
Inhaled bronchodilators are used as “rescue”
therapy on an “as needed” basis.
Bronchodilators should be given 15
to 30 minutes prior to inhaled steroids.
This helps open the airways so the
steroid reaches further into the lungs.
A long acting inhaled bronchodilator
such as Salmeterol can be used, but
in some cases a shorter acting but less
expensive option such as Albuterol is
more reasonable.
The oral bronchodilator Ventipulmin
(clenbuterol) is less effective, but can
be used if inhaled bronchodilators are
not an option.
Diagnosing and treating allergies can
help decrease the need for steroids and
bronchodilators. Allergy testing can be
done with a blood test or by intradermal
testing. The latter is more accurate, but
also more difficult to do. The blood
allergy test is controversial among veterinarians
because of the high number of
positives to antigens, but I have found it
to be a helpful guide.
Once allergens are identified, they
should be eliminated or minimized.
In cases where exposure is unavoidable,
allergy shots may be helpful.
Antihistamines such as tri-hist granules
or hydroxyzine may also help in these
cases early on, but tend to be less useful
as the condition progresses.
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Published in the May/June 2008 issue of Equine Wellness Magazine |
