Page 99 - September 2020

CONSEQUENCES OF STALL CONFINEMENT by Nancy S. Loving, DVM
It is common for horses in training to spend a majority of their time in a stall or a small paddock. There are consequences to this lifestyle and by understanding about how stall confinement affects a horse’s physical and mental health, you can take measures to mitigate these effects.
THE STALL ENVIRONMENT
Within the stall environment, there are microclimate effects of an enclosed space. While viruses and bacteria pose risks to
airway health, environmental exposure to particulates dispersed from feed, bedding, footing materials, and other sources (such as diesel exhaust from tractors) all can lead to inflammatory airway disease (IAD), currently referred to as equine asthma. Horses living in a dusty environment have increased mucus in the airways, and even a moderate amount of mucus impairs performance.
One critical substance that generates respiratory inflammation is endotoxin,
a component of the bacterial cell wall of Gram-negative bacteria, which is liberated
as these bacteria die. Endotoxin is found
in large quantities in fecal matter, hay, and straw. One practice used to minimize dust and respiratory irritants is to soak the hay; however, only feed as much wet hay as can be consumed quickly. The exponential nature of bacterial growth in moist materials makes wet hay a rich source of endotoxin.
Endotoxin tends to adhere to airborne particles, which are then inhaled. Its potency is not good for animals or people to breathe. This foreign protein (referred
to as an antigen) elicits an aggressive inflammatory response. Studies have shown that dust exposure by horses prone to respiratory disease (like heaves) creates lots of inflammation and breathing difficulty, especially when dust contains endotoxin, which is an important stimulus of equine respiratory problems.
Individual horse behavior also affects degree of exposure -- for example, a
horse that defecates in a corner lessens its exposure. Good ventilation with ample air changes per minute is important to airway
health. A fan may not carry air flow out
of the stall, instead generating a whirlpool effect that whips up dust and endotoxin. Increased dust particle concentrations occur in stalls in proximity to manure handling, air-moving fans, or foot traffic.
Even when a horse is pastured outside, this doesn’t ensure minimal exposure to endotoxin. Both wind and foot stamping by horses congregating in one area tend to stir up manure and dust to expose airways to endotoxin similar to what is experienced in a stall environment.
There are suggested strategies to minimize environmental dust:
• Use quality, low-dust hay and bedding.
• Clean stalls regularly – twice daily is best – to
remove manure and urine-soaked bedding. • Minimize human activity such as raking
and sweeping while horses are inside and eliminate the use of leaf blowers within the stable.
• Place fans so they don’t whip up barn or stall dust.
• Provide good ventilation throughout the barn.
VETERINARY VIEWS
THERE ARE MANY SUGGESTED STRATEGIES TO MINIMIZE ENVIRONMENTAL DUST
Use quality, low-dust hay and bedding. Clean stalls regularly to remove manure and urine-soaked bedding.
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