FearThe
Fungi
Inflammatory Airway Disease (IAD) affects huge numbers
of horses and often goes undetected while impacting their
performance. A three-year research project published
by The Journal of Veterinary Internal Medicine expands
extensive past research confirming IAD’s prevalence. Older
studies identify over 80% of the general horse population as
having it. Conducted by a group of equine sports medicine
veterinarians in Belgium, this new research studied
over 700 active sport horses referred for performance issues
or possible respiratory problems: 88% were diagnosed with
IAD.
The study also cited high-temperature steamed hay as critical
to preventing IAD: horses fed steamed hay were 65%
less likely to develop the condition than those fed dry hay.
Led by Dr. Julie Dauvillier, the study is the first to connect
fungi in the horse’s respiratory system with high incidence
of IAD. Along with many inhalable irritants, fungi are present
in even top quality hay. High temperature hay steaming
kills fungi, hence its effectiveness in preventing IAD.
“This paper highlights a major piece of the puzzle of equine
airway diseases: the role of fungi,” explains Dr. Van Erck-
Westergren, co-author of the study. “In human medicine,
fungi are known to cause many respiratory inflammatory
conditions such as allergies, infection, asthma, etc.
In equine veterinary medicine, we can find publications
that relate the role of fungi in pretty nasty, potentially lifethreatening
diseases such as fungal pneumonia or guttural
Fungi Found Everywhere
Health
pouch mycosis, but barely anything else. Our paper shows
for the first time that ubiquitous molds, including fungi,
cause chronic lower airway inflammation which is deleterious
for the health and performance of our horses.”
EQUINE Along with dry hay, straw bedding had a high correlation
to IAD incidence. Dry hay and straw bedding “cannot
be recommended in performance horses,” Dr. Van Erck-
Westergren states.
62 www.EliteEquestrianMagazine.com Continued...
Recently published 3-year
study cites steamed hay
as critical to preventing
IAD, a stealth equine
ailment that affects over
80% of horses.
by Kim F Miller
The study also found that soaking hay, haylage and “dust
free” hay did not reduce the risk of fungi-related IAD, while
wood shavings were deemed the best option for stalls that
require bedding.
“Fungal spores naturally contaminate hay and straw during
harvest,” the study’s authors explain. “The degree of contamination
and proliferation is directly related to harvesting
practices, initial levels of soil contamination, as well as
storage conditions.” Of the 731 active performance horses
in the study, 79% were found to have fungal elements in a
cytological examination of tracheal wash fluid. Horses with
fungi in their airways were twice as likely to develop IAD
than those without it.
IAD is a stealth illness. It sometimes presents with an
occasional cough and mild nasal discharge, but often lurks
without symptoms. Unexplained decreases in performance
are complaints that often lead to bronchoaveolar and
trachea washes that reveal an IAD diagnosis. Unmanaged,
this condition will progress and potentially mean these
horses are more susceptible to debilitating extremes of
the Equine Asthma Spectrum, including Recurrent Airway
Obstruction, aka “heaves.”
While the study answered questions about prevalence
and dangers of fungi, it raises others that warrant
further investigation, especially for active sport horses. “A
link between fungal growth and an immunodepressive
state could not be demonstrated in our study,” the authors
noted. “However, it is likely that the immune system of
some of the horses included in our study would have been
challenged by intensive training, regular transport and
competition.”
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