airway obstruction (RAO)
Recurrent airway obstruction (RAO) is also known as heaves
and was previously termed chronic obstructive pulmonary disease
(COPD). Horses with RAO may develop an increased effort of
breathing, nasal discharge and cough when exposed to allergens
(mainly moulds) found in some forms of bedding or forage.
Therefore a minimum-dust management regimen is a permanent
requirement for horses with RAO to minimise the horse's exposure
to potential allergens. Failure to maintain an adequate minimum-dust
regimen carries a major risk of recurrence of symptoms in
horses with RAO and may be a factor in causing this disease.
The Respiratory Physiology group has identified that
the concentration of ascorbic acid in the lung is decreased
in horses with RAO and dietary supplementation with derivatives
of ascorbic acid may decrease symptoms of the disease.
Studies have also focussed on developing non-invasive and
reliable methods for the measurement of airway inflammation
and airway constriction in order to diagnose the disease rapidly
so that treatment can be administered prior to the development
of clinical symptoms.
Other investigations have involved the use of nuclear scintigraphy
to image ventilation in RAO horses.
The WALTHAM Centre for Pet Nutrition, Marksway Horsehage
and the Home of Rest for Horses have supported RAO research
at the Animal Health Trust in recent years.
1. The best method of minimum dust management is
to keep your horse permanently out of doors away from all
stores of bedding, feed and muckheaps. Your horse should therefore
be turned out as much as possible. Even if (s)he cannot be
kept permanently outside, turnout encourages horses to lower
their heads whilst grazing and to move around, in addition
to reducing exposure to stable dust.
2. When your horse is stabled the box should be large,
clean and well-ventilated. Loose boxes with external doors
and windows are best; American barn systems are generally
3. Maximum ventilation in stables should be maintained even
in cold weather. The top door of the stable should be kept
open at all times.
4. Stables should be fully cleaned out and washed down before
occupation and on a regular basis to prevent build up of mould
and dust (e.g. every 2 - 3 months) using a suitable disinfectant.
5. The horse's stable should not share its air space with
stables not on minimum-dust management, feed and bedding stores
or muckheaps. Ideally minimum-dust boxes should be located
at least 50m upwind of these.
6. The use of rubber matting can in many cases obviate the
need for bedding. Paper and cardboard are lower in dust and
mould content than other beddings. Some horses can however
be adequately managed on wood shavings. Straw bedding generally
has the highest mould content and is therefore unsuitable.
7. Bedding should be maintained as clean as possible by efficient
regular mucking out to prevent mould build up in soiled bedding.
Deep litter systems are totally unsuitable.
8. Your horse should be taken out of the stable for mucking
out as airborne mould dust increases dramatically at this
time. After mucking out, allow the dust to settle before returning
your horse to the box.
9. Mould free products such as Horsehage, complete
cubes or silage should be substituted for hay. If hay must
be fed, use the best quality hay available, but only feed
it after soaking it thoroughly for several hours (even the
best hay has a high mould content).
10. Feeding your horse from the floor will encourage lowering
of the head and hence aid in clearance of secretions from
Travelling your horse
11. If you transport your horse, ascertain beforehand
what minimum-dust measures can be provided where (s)he will
12. If substandard accommodation cannot be avoided it may
be possible to prescribe medication to help your horse whilst
(s)he is away. If your horse is competing, medication rules
may preclude this.
13. The horse's environment in the transporter should conform
to a similar standard of minimum-dust management as the stable
environment (ventilation, bedding, feed).
14. Your horse should be tied so that (s)he can safely lower
his/her head during transport.
15. Avoid working your horse in a dusty environment
(e.g. dusty indoor schools)
16. Observe your horse regularly so that you are able to detect
the earliest signs of respiratory abnormalities and seek veterinary
advice concerning them.
17. If you have any questions concerning the correct environment
for your horse, you should contact your veterinarian for advice.
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