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IF IT
IS POSSIBLE FOR ADULT HORSES TO CHANGE
IN HEIGHT
Simon Richards BVSc MRCVS
Hook Norton Veterinary Group
Richard Sutcliffe BVM&S MRCVS
Bishopton Veterinary Group
Yes, I do find that adult horses and ponies
do change in height even under the
relatively controlled conditions of properly
conducted JMB measurements.
Undoubtedly some animals mature later and
continue to grow for longer than others, but
conversely ‘with age - comes wisdom’ and
older animals tend to relax more quickly
and to a greater extent than youngsters.
Since the spine is supported between the
forelegs only by muscle, the more relaxed
these muscles are, then the lower the
withers become.
Preparation before measurement is
important. An animal being fed large
quantities of hard feed, perhaps presented
lame will be unwilling to stand still. On a
cold, windy day with agitated handlers,
who arrive late and have not practiced at
home standing the horse still or introduced
him/her to a measuring stick; will result in a
higher measurement than could be obtained
under more conducive conditions.
AUTUMN 2013 ISSUE
EQUINE MATTERS
20
It is fortunate that there is no evidence of
significant height change in ponies once
they have reached maturity. I believe that
the Life Height Certificates issued by the
JMB for seven year olds and over are
likely to remain accurate for the
remainder of an animal’s working life.
Human inter-vertebral disc compression
is responsible for the significant reduction
in our height comparing evenings to
mornings whilst diseases such as
osteoporosis causing bone shrinkage are
often behind the obvious loss of height
that starts in middle age.
Anatomical considerations indicate
that disc changes cannot influence
equine height measurement. Equine
diseases such as pedal bone sinking or
hyper-extension of the fetlocks may be
implicated in significant height reduction
but would also preclude a successful
career in the showring.
Following the recent reports on the large
height increases in the European
population; it is lucky that ponies are not
shrinking or we could find future show
rules having to adjudicate on the wearing
of rollerblades on long-legged riders!
Can adult ponies
change in height
measurement?
Jane King BVetMed MRCVS
Westmorland Veterinary Group
The short answer in my opinion is ‘YES’.
Horse's leg bones actually stop growing
when they are about three but they appear
to continue to increase in height as they
mature beyond this. Height is measured at
the withers, but these do not have a direct
bony connection to the ground. Unlike us,
the horse has no collar bone. The front legs
which take the bulk of a horse's weight are
connected to his body by a muscle sling
supporting the rib cage. As a horse
improves his fitness and training,
strengthening these muscles lifts the ribs
making him appear taller.
We have also probably all experienced
the horse who appears to grow as he
arrives at an exciting competition, similarly
fatigue, dehydration, sedation or lack of
condition as well as foot trimming can all
make the horse appear smaller.