REDUCING THE RESPIRATORY CHALLENGE
Over the past few decades, we have become more aware of
respiratory disease in horses and the need to pay close attention
to the environment as well as the horse’s diet, in order to reduce
the level of exposure to the disease-causing agents.
If the horse is suffering from a viral or bacterial infection of the
respiratory tract, or an allergic response to the presence of
inhaled fungal spores or noxious gases, this can cause
inflammation of the small airways, increased mucus production
and bronchiospasm, and the condition can be exacerbated by a
‘dusty’ environment.
The connection between respiratory tract infection and allergic
respiratory disease is well-known in human medicine and it
appears that horses are more sensitive to respiratory allergens
following an infection of the respiratory tract, since the damage
to the airways caused by the infection allows easier access of
airborne allergens to the sensitive tissues. Not all viral or
bacterial infections will result in the horse becoming sensitized,
but recovery time after respiratory infection is prolonged in the
presence of environmental contaminants. Once a horse
develops a dust sensitivity (which can occur over a period of
years of being exposed to environmental pollutants), it will
remain so for life.
The Contaminants
Fungal Spores
Hay is probably the single most common source of fungal
spores, mostly caused by baling at too high a moisture content.
A horse eating mouldy hay or stabled on a contaminated bed
may inhale millions of spores with every breath.
More importantly, significant levels of fungal contamination
may be seen in hay which looks and smells ‘clean’, which means
the challenge to the respiratory system can be greater for horses
that are fed hay. Even when hay is soaked before feeding, some
spores are still ingested along with any toxins that may be
present, and as the wet hay falls to the floor and dries, the
spores become airborne once again and are inhaled by the
horse as well as contaminating the bedding. Other feedstuffs
which are poorly stored may also be a source of fungal
contaminants.
26 | Rural Life