The Respiratory Challenges Of Equine Performance
Improving the horse's ability to breathe ensures
more efficient production of ATP, the fundamental energy
molecule of the body. Aerobic metabolism (when the horse
is absorbing sufficient oxygen) produces approximately
10 times more ATP than anaerobic metabolism (when oxygen
supplies are inadequate to meet demand). By selecting
focused nutritional support and an effective training
program, you can make a substantial improvement in your
horses' respiratory efficiency. There are also important
steps to take in daily management that can have a major
impact on respiratory health. Here are the ones we have
found to be most important. Although some of these risk
factors can be reduced with nutritional support, all of
them should be addressed in the management program.
1. Airborne particles
- dust, soot, mold spores, grain and hay dust. All create
inflammatory response, which decreases airway function.
Particles lead to: a) excessive mucus secretion, b) susceptibility
to infection of inflamed tissues, c) bronchial constriction,
d) formation of cyst-like structures to isolate and reduce
irritation, thus reducing respiratory efficiency of the
- Keep shedrows, stable and paddock areas as dust-free
as possible; wet down frequently, consider alternative
- Maintain optimum ventilation in all enclosed areas.
- Eliminate all feedstuffs of questionable quality;
allow no feed that appears dusty or that may contain
- Consider alternative sources of roughage in the diet,
to reduce or replace hay. For example, some feed
manufacturers offer formulas that supply high roughage
levels (usually with beet pulp) so you can reduce
the amount of hay you feed.
- Substitute dust-free wood shavings for straw as bedding
2. Ammonia - highly irritating fumes
from horse's urine. High ammonia levels in stalls lead
to inflammatory response and damage the respiratory epithelium.
- Muck-out stalls as frequently as possible.
- Make sure bedding is deep enough to efficiently absorb
- Insure that ventilation system is efficiently exchanging
air at a level at least as low as that of the horse=s
- Consider crude protein levels versus protein quality
(amino acid balance). Excessive crude protein will
create significantly higher ammonia levels in urine.
Improve protein quality.
3. Ozone and other gas pollutants -
ozone (O3) is a highly unstable, reactive oxygen
form that is an increasing pollution problem in metropolitan
areas. It is highly irritating to mucus membranes and
a very potent generator of free radicals. Leads to inflammatory
response and cell wall damage. Other gas pollutants causing
similar problems include aromatic hydrocarbons, sulfur
- The location of the stables is the main factor in
the severity of this problem. Make sure ventilation
system does not make this problem worse.
4. Feed contaminants - mycotoxins (aflatoxin,
zearalenone, trichothecene, etc.) endophyte and other
fungi infestations of grain and hay. All are known to
be destructive to cell membranes, reduce growth, and can
be insidious (result in subclinical problems) in low contamination
levels. Mycotoxins are most commonly found in grains.
Endophyte infests fescue (grass hay/forage).
- Request that your feed dealer verify that all feeds
are free of these contaminants. A fluorescence assay
is used to identify mycotoxins, which typically
are not visible to the naked eye.
- Identify forage and hay grasses and have any fescue
checked for endophyte contamination. Although reports
of problems from endophyte contamination have focused
on gestational disorders, endophyte reduces performance
in all horses.
5. History of respiratory infections
- Many veterinarians have noted a propensity for bleeding
problems and other respiratory disorders in horses who
suffered significant respiratory infections as juveniles.
Pulmonary or bronchial lesions may be formed which may
be "weak spots" in the future. Such horses should
be considered to be at higher risk of respiratory disorders
during their performance careers.
- Maintain extra vigilance in following these guidelines
for horses with this type of history.
- If respiratory infection is suspected, suspend high-
intensity exercise immediately until the horse receives
a clean bill of health.
6. Anemia - low red blood cell (erythrocyte)
count and/or low hemoglobin level. Although there are
several possible causes of anemia, the two most common
causes are diet and EIPH (exercise induced pulmonary hemorrhage,
or bleeding). Anemia lowers the capacity of blood to carry
oxygen and carbon dioxide. This in turn makes higher demands
on the cardio-pulmonary system; higher blood pressure
and heart and breathing rates, leading to greater mechanical
challenge to the pulmonary capillary beds. Anemia is also
likely to be accompanied by decreased deformability of
the red blood cells. Red blood cell deformability is essential
for efficient flow through the capillaries and minimum
abrasion of capillary walls.
- Insure adequate nutrition for red blood cell and
- Make sure that non-nutritional anemia is not present.
Consult your veterinarian.