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B E H AV I O U R
SUMMER 2011 ISSUE
EQUINE MATTERS
8
MAT F E RNANDE Z
Horses that try to kick the farrier when he or she is about
to pick up a hind leg to start shoeing, might be suffering
from pain...
feed-bucket. While they apparently have a
ravenous appetite, they are often notorious
bad-doers. Some others will be constantly
on edge with an array of very ill-tempered
reactions to the most minimal interaction.
Travel to competitions can also trigger a
state of anxiety in some horses and in serious
cases they will become unmanageable. All
these behaviours can be explained by the
discomfort and, sometimes, obvious colic
pain caused by stomach ulcers (EGUS).
We try to stop vices (i.e. the symptom)
because of the irritating and damaging
effects when they are performed (e.g. colic
associated with wind-sucking). However,
recent work suggests that some of the
resulting ‘effects’ of stereotypical behaviour
(e.g. digestive disorders, colic) may in reality
reflect underlying problems that the horse is
attempting to comfort by performing the vice.
In such cases, attempts to prevent the
behaviour could do more harm than good.
With crib-biting and wind-sucking the horse
might be trying to increase the production of
saliva to buffer an increased acidity in the
stomach resulting from EGUS. Any forceful
attempt to stop these two activities without
addressing the underlying problem will stress
the horse. Since gastric ulcers are linked to
stress, this will compound the problem.
Weaving develops as a form of frustrated
escape response. This is clear because the
vice worsens when the stable-mate is taken to
the field. Box-walking is the consequence of
confinement to a stable impeding the natural
behaviour of the horse. Both vices lead to an
excessive use of energy with consequences
on the horse's body weight. Asymmetrical
musculature can develop if pacing is always
in the same direction with resulting problems
for saddle fit. Excessive sweating and injuries
against the wall or the door of the stable can
also result.
Wood-chewing is usually caused by
boredom, lack of exercise and nervousness
but can be associated with dental problems,
parasites or mineral deficiencies.
Pica is the ingestion of non-nutritive or non-food
items (wood, soil, faeces) which can be
caused by boredom but mainly by deficient
diet with all the possible health implications.
Coprophagia or eating faeces (a type of pica),
while normal in foals, might indicate a diet
poor in protein and has been linked (either as
a sign or as a consequence) with equine motor
neuron disease in which the predisposing
factor is a diet rich in grain and with poor
quality grass or hay or no access to grazing.
Other abnormal behaviours
The third big group includes a range of
abnormal behaviour from headshaking to
frank demented episodes which are the result
of neurological abnormalities and, therefore,
devoid of any control on the horse's part.
Headshaking describes the uncontrollable
reaction caused by abnormal and
unpleasant/painful nerve signals from structures
in the head. Most commonly the lining of the
nasal cavity is affected but the eye and teeth
can also be responsible for some cases. It is
thought to be due to a malfunction in the nerve
supply in these areas. The signs range from
snorting and rubbing of the nose over the knee
or a wall to severe, violent jerking movements
of the head, often violent enough to make the
horse unrideable. The issue is that, in the early,
mild stages, the head movements (and the
resulting disturbance of the desired rhythm and
outline) can be confused with a stubborn
opposition to being ridden in a properly
schooled manner.
Not to be confused with box-walking is the
compulsive walking that is associated with
hepatoencephalopathy (a very serious and
often fatal development of liver disease).
The disease produces, amongst some other
signs, depression, incoordination, yawning,
head-pressing against fixed, cool structures
and periods of somnolence.
Narcolepsy-like behaviour is seen when
a horse falls asleep or collapses at an
inappropriate time e.g. during grooming. It is
often associated with sleep deprivation which
can occur when the horse suffers from an
orthopaedic condition that impedes him from
resting at night. In this case, the presentation
of an odd behaviour is the result of pure
exhaustion. Once this cause is established
(and it might require monitoring the horse
with a CCTV system at night for a few days
running) the vet can proceed to investigate
the cause of the musculo-skeletal condition.
I N S UMMARY
The horse's behaviour might be the only
obvious sign of a health issue. It is less
detrimental to the animal's welfare to
prove that we are dealing with a
behavioural issue, only after ruling out injury
or disease, than to brand the horse as badly
behaved and in need of ‘sorting-out’.
Aggression
Kicking
Biting
Bucking
Environmental threat
Pain/discomfort
Vices
Anxiety at feeding/travel
Crib biting & Wind-sucking
Weaving
Box walking
Wood Chewing
Pica
Coprophagia
Stomach ulcers (EGUS)
Confinement
Boredom, dental pain
Mineral imbalance
Inadequate protein
Equine Motor Neuron disease
Neurological
Head shaking
Hepatoencephalopathy
(walking, depression,
headpressing)
Narcolepsy
(inappropriate sleep)
Nerve dysfunction
Liver disease
Sleep deprivation
Orthopaedic pain
Behaviour type
Presenting signs
Possible causes