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How will my horse respond or cope
with the loss of an eye?
Understandably this is a frequently asked
question and the answer is that they normally
cope and adjust very well. An eye is generally
removed because it is painful and ocular pain
can be particularly distressing. Once removed
the patient will normally, after a few days,
become more relaxed and begin to put on
condition due to the reduction of pain.
The surgical procedure
The surgery is normally undertaken under
general anaesthetic to make it easier for the
surgeon to operate. However, over recent
years, an increasing number of operations are
undertaken with the patient standing, under
heavy sedation with the use of nerve blocks
and local anaesthetic. This can be of benefit
to older, quieter patients where a general
anaesthetic can pose a greater risk.
The surgery can involve removal of the eyeball
or the eyeball and some of the surrounding
structures. Whichever technique is employed
will depend on the reason for removing the
eye. If removal of the eye is due to cancer as,
for example, the horse in
figures 1, 2 and 3
,
additional tissue from the eyelids will need to
be removed to provide an adequate margin to
ensure that all the diseased tissue is removed.
A prosthetic implant can be inserted in place
of the eye that is removed. This can provide
a more aesthetically pleasing appearance,
giving the impression that the horse has just
closed its eye or is winking at you! The
downsides of fitting a prosthetic eye are:
1.
An increased chance of wound breakdown
due to a slightly increased risk of infection
being trapped during the operation or
rejection of the implant by the body’s
immune system.
2.
Difficulties of placing an implant that is not
a perfect fit, either too big or too small. This
is because it is difficult to predict how the
tissue, within the eye socket, will ultimately
settle down after the operation.
The horses in
figures 4 and 5
show how the
horse will look a few months after enucleation
with and without a prosthetic eye.
Surgical feature:
enucleation
Removal of an eye is called enucleation; it is usually a procedure of last
resort. Enucleation is undertaken when treatment for a disease has
been unsuccessful; for example, uncontrolled equine recurrent uveitis
(ERU) or where there is irreparable trauma. It is not a small procedure
for the horse, pony or donkey and it can be quite a daunting undertaking
for the owner to contemplate.
Veterinary Nurse
Dominic Alexander
XLEquine Practice
Belmont Veterinary
Centre
13
EQUINE MATTERS
SURGI CAL FEATURE
Dominic Alexander BVMS MRCVS,
Belmont Veterinary Centre
Figure 2: regional nerve blocks being
applied
Figure 3: the eye removed and the socket
closed post surgery
Figure 4: enucleation without a prosthetic eye
Figure 5: enucleation with a prosthetic eye
Figure 1: cancer that has migrated from the
third eyelid into the eye