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RESPIRATORY DISEASE IN HORSES –
WHAT TO EXPECT IN WINTER
By Helen Whitbread of Deben Valley Equine Veterinary
Clinic
Well as the freezing temperatures and muddy
conditions arrived, most horse owners in the
UK rushed to protect their horse from the weather.
Shorter days mean most horses spend longer stabled
away from the fresh air of outside. Extra stabling
and rugging means more handling by a variety
of friends, grooms or other horse owners. Many
horse are kept in a shared air space and just
like children attending school our horses are
exposed to each others bugs and the 2 very different
environments of
1) outside, a fresh field and
2) inside warmer stable / barn with the reduced
airflow of a confined ‘non-draughty’
space.
Often vets see a seasonal peak in coughing horses
in Spring and late Autumn, just when horses
are changing their coats. As mentioned above
the 2 main factors contributing to this are
changes in the weather and changes in management.
Also horses suffer from a range of infectious
respiratory diseases such as ‘flu, herpes
virus or strangles. Some of these diseases then
predispose horses to allergic airway problems
such as COPD / RAO, summer heaves or even head
shaking. Once the respiratory system is damaged
it can not recover; in the same way that the
airways can not respond to fitness training
nor can damaged tissue repair; once some airway
function is lost, the horse has to cope with
its remaining normal tissue. Some details of
respiratory problems follow, but more details
will follow in the next newsletters…
CLINICAL SIGNS
Common things that owners may note include:
-
Coughing – dry, harsh, frequent, occasional,
spasmodic, relentless etc.
Nasal discharge – 1 or both nostrils;
clear, white, brown, yellow or green - Watery
or thick, lumpy etc.
Wheezing or gurgling sounds from the throat
or chest
Swollen around throat Flared nostrils
Fast breathing rate (normal rate is 8-12 breaths
per minute at rest)
Increased breathing effort – abdominal
effort or double breathing
Heave line (tight abdominal muscle)
Reluctance to eat
High temperature (normal 99.5 - 100.5°F
or 37.5 - 38° C)
Exercise intolerance
Poor performance
Head shaking
CAUSES – adult horses
Allergic airway disease (COPD / RAO / heaves)
(dust, moulds etc.)
Equine Influenza Virus
Equine Herpes Virus
Other viruses
Strangles (Strep. equi)
Other bacteria
Fungal infections
Sinus disease
Lungworm
Abscess / tumour / cyst / foreign body
Laryngeal hemiplega (Recurrent Laryngeal Neuropathy,
‘roarer’)
Inflammatory airway disease (irritant induced
e.g. ammonia & others)
Recurrent Airway Obstruction (RAO, COPD, Heaves
or Dust Allergy) is an extremely common problem
seen particularly in the stabled horses where
inhaled particles cause an allergic reaction
within the airways, very similar to a human
developing asthma and horse will present sometimes
with coughing or breathing difficulties, sometimes
wheezing can be heard. It is the commonest kind
of respiratory disease treated in the UK and
needs dramatic management changes to prevent
a chronic state developing. It is often secondary
to other respiratory diseases such as herpes,
Flu, Strangles and the numerous other respiratory
viruses that horses can suffer from.
Causes will be discussed further in future
newsletters…
DIAGNOSIS
As a horse owner, your concerns are:
-
What is wrong with my horse?
Can I work my horse?
Will other horses catch it?
How do I make my horse better?
How long will my horse take to get better?
These are all questions that your vet will
be able to answer, but sometimes only after
test results have been obtained. Initially your
vet will examine your horse, recording body
temperature, heart rate, breathing rate and
effort. Your vet will listen with a stethoscope
(auscultate) to breathing sounds all over the
chest and may be over the windpipe. A vet will
also pay particular attention to any of the
clinical signs listed above or things that you
mention – remember you know your horse
better than anyone else. Your vet will also
pay particular attention to your stabling and
management. It may be possible to reach a (presumptive)
diagnosis straight away or further tests may
be suggested.
FURTHER TESTS
Blood tests – routine
haematology may suggest a viral or bacterial
cause
Blood tests –
specific for a certain infection e.g. Influenza
or strangles
Swabs – nasal
or from the back of the throat or burst abscess
Endoscopy –
a fibre-optic tube allowing the vet to look
along the airways from nostrils to the end of
the windpipe including guttural pouches and
collect samples along the way
Dynamic Endoscopy
– a special fibre-optic tube attached
to the bridle which allows the vet to watch
the back of the horse’s throat (pharynx
/ larynx) while the horse is galloping along
Radiography –
the advent of digital radiography has meant
this is a much more useful technique for identifying
lung disease
Response to treatment
Ongoing monitoring of horse
TREATMENT
Drugs may be necessary and can be delivered
by injection, in feed or via an inhaler.
Antibiotics may be appropriate if bacteria
isolated
Mucolytics to loosen mucus / pus
Bronchodilators to open up ‘narrowed’
airways
Steroids to reduce airway inflammation / allergic
reactions
Non-steroidals e.g. ‘bute’ to reduce
throat pain and lower high temperature
Dust free management is much better long term
to avoid drugs for your horse and costs to your
pocket! The idea: to reduce the amount of dust
and mould spores in the air your horse breathes.
Plenty of fresh air is the key! As much turnout
as possible. Air inside a stable should be the
same quality as outside!
Good ventilation. Consider creating extra windows
– diagonally across from the door is best
or remove a couple of planks just below the
guttering at the back of the stable; horses
do not mind cold air if well rugged and dry.
If your stable has lots of cobwebs and/or mould
patches on the roof then it has poor airflow!
Dust-extracted bedding materials e.g. paper
or cardboard. Although initially more expensive
these can be economical to run, especially if
used with Rubber matting - only a little bedding
is needed to absorb moisture. Shavings can become
dusty and harbour mould as they get older –
avoid accumulating deep banks. Clean straw (although
not suitable for some horses) is better than
deep dirty shavings.
Have your horse well away from the stable when
you muck out – the dust, mould and ammonia
released into the air when mucking out will
undo all your hard work otherwise! The muckheap
needs to be well away from your stable too.
Similarly, groom in a well ventilated place.
Feed from the floor to allow the horses lungs
to drain normally.
Soaking hay for 20-30 minutes causes the mould
spores to stick to it, so the horse eats and
digests them harmlessly rather than breathing
them in. Shake hay well before soaking. Change
soak-water daily. Clear away any leftover bits
every feed. Alternatively, feed haylage or some
horses will tolerate feeding hay by immersion.
If your stable adjoins others, their management
needs to be as good as yours!
PREVENTION
A horse’s lungs are continually dealing
with attack from airborne moulds, bacteria and
viruses, not to mention dust and ammonia, which
cause irritation, inflammation and increased
mucus secretion. Some horses are more sensitive
– those suffering from allergic airway
conditions such as COPD/RAO or recovering from
viruses. However many horses who are not (yet)
showing signs of airway trouble such as a cough,
getting out of breath or a nasal discharge,
can also be helped.
Reducing the attack which their body is fighting
off all the time can help reduce the likelihood
of them developing problems in the future, and
improve their performance and fitness...
Respiratory disease can be prevented by good
stable and air management (dust free management
see above) as well as vaccinating against Herpes
and ‘Flu.
A good yard will develop an isolation facility
so that new horses coming in can be kept separated
for three weeks and monitored for signs of disease
before being mixed with other horses on the
yard.
Ask your vet for some good advice.
This article has been kindly provided by
Helen Whitbread BvetMed CertVR MRCVS
Deben Valley Equine Veterinary Clinic,Birds
Lane,Framsden,Suffolk.IP14 6HR
01728 685 123
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