Periorbital eczema is a
common skin condition in the UK often resulting when sheep have too
little space allowance at feed troughs and trauma to skin allows
entry of Staphylococcus aureus causing severe local
infection. Affected sheep have markedly swollen eyelids which block
vision in that eye. Ewes with both eyes affected are blind. Healing
lesions have sharply-demarcated hair loss extending to 2 to 3 cms
around their eyes.
Suprisingly, a single
intramuscular injection of procaine penicillin affects a rapid
response within 24 hours. Ewes with impaired vision in both eyes
should be housed to ensure adequate feeding and prevent death by
Periorbital eczema can be
prevented by appropriate space requirements at the troughs (450 mm
per sheep). An alternative regimen involves feeding the grain
ration as cobs on a clean area of pasture using a
Infectious Keratoconjunctivitis (IKC,
contagious ophthalmia, "pink
keratoconjunctivitis is often associated with adverse weather of
high winds and driving snow during the winter months giving rise to
the colloquial term 'snow blindness'. Large numbers of sheep can be
affected during these weather conditions. Competition at feed
troughs and hay racks also increases the rate of spread of this
Infectious keratoconjunctivitis is often associated with adverse
weather of high winds and driving snow.
Competition and trauma at feed troughs and hay racks may increase
the rate of spread.
The condition can affect one
or both eyes. Most cases are selected for treatment on the basis of
tear-staining of the face. On closer examination of the affected
eye(s) there is marked conjunctivitis. There is forced closure of
the eyelids when sheep are exposed to bright sunlight. More
advanced cases show keratitis, and possibly corneal
Fig 3: Very
early stages of IKC affecting the sheep's right
Fig 4: Forced
closure of the eyelids and tear-staining of the
Fig 5: On closer examination of the affected
eyes there is marked conjunctivitis.
Fig 6: Marked conjunctivitis - the eye looks
red instead of its normal white colour.
Fig 7: The discharge from the eye has become
purulent matting the eyelashes.
In severe cases, ulceration
may progress to rupture of the anterior chamber but this is
uncommon. Sheep may die from misadventure if the condition causes
temporary blindness. During late pregnancy, twin lamb disease may
result in multigravid ewes as a consequence of blindness and
inability to find sufficient food.
Fig 8: Rupture of the anterior chamber of the
Affected sheep should be
housed with ready access to food and water. A single intramuscular
injection of long-acting oxytetracycline is economically
justifiable and very effective in sheep. Topical antibiotic therapy
cannot always be accomplished every day for 3-4 days under farm
conditions. Immunity following infection is poor, and lesions may
Fig 9: This
heavily-pregnant ewe has been penned with other affected sheep to
reduce competition at feeding times.
Provision of shelter from
storms is good husbandry practice on hill/mountain pastures.
Adequate trough space and feeding concentrates on the ground may
limit spread of infection throughout the group. Outbreaks of
infectious keratoconjunctivitis may occur after the introduction of
purchased stock therefore, whenever possible, all new stock should
be managed separately as one group away from the main
Anterior uveitis, also
referred to as ovine iritis, probably follows conjunctival
infection with Listeria monocytogenes, is occasionally
seen in sheep of all ages being fed on big bale silage.
The initial presenting signs
are excessive lachrymation, forced closure of the eyelids, and
photophobia affecting one or both eyes. Within two to three days,
the surface of the eye develops a bluish-white opacity. Regression
of ocular lesions takes some weeks without treatment.
Fig 10: Early
Fig 11: The
surface (cornea) of the eye has become blue and opaque rendering
the sheep temporarily blind in this eye.
There is a marked response to
a combined subconjunctival injection of oxytetracycline and
dexamethasone administered by the veterinary
Fig 12: Iritis
is usually associated with feeding big-bale
It proves difficult to feed
big-bale silage in another way to sheep. Attention to detail when
baling and wrapping silage, and ensuring appropriate fermentation
conditions, should limit contamination with L.
monocytogenes. However, exposure to air for many days before
the large bale is eventually eaten provides an ideal environment
for L. monocytogenes multiplication.
Entropion (in-turned eyelid)
is a common hereditary problem of many sheep breeds and their
Inversion of the lower eyelid
is either present at birth or appears soon afterwards. The ocular
discharge quickly becomes purulent. Direct contact between the
eyelashes and cornea causes a severe keratitis with ulceration in
more advanced cases with consequent blindness. The condition
frequently affects both eyes.
Fig 13: Entropion
In simple cases the lower
eyelid is everted by rolling down the skin immediately below the
lower eyelid. Topical antibiotic is then applied to the cornea to
control potential secondary bacterial infection. In addition, this
oily presentation lubricates movement of the lower eyelid thereby
reducing the likelihood of inversion.
If eyelid inversion recurs
after rolling out the lower eyelid, subcutaneous injection of 0.5
mls of antibiotic, often procaine penicillin, is injected into the
lower eyelid. The lamb is securely held by an assistant and a 21
gauge 15 mm needle introduced through the skin of the lower eyelid
parallel to, and approximately 1 cm below, the lower eyelid. This
volume of antibiotic effectively everts the lower eyelids and forms
a depot to control possible secondary bacterial
Thin metal clips which are
placed at a right angle to the eyelids, and closed using fine
pliers (Eales clips), can also be used to evert the lower eyelid.
These clips have the advantage that they can be inserted quickly by
Excision of an elliptical
strip of skin and drawing the cut edges together with sutures can
be used to evert the lower eyelid but is rarely
Entropion is managed by
regular inspection of all newborn lambs to ensure that the lower
eyelids are normally everted.
The genetic component of
entropion should be carefully investigated and when the condition
can be attributed to certain ram(s), they should be culled but in
reality this never happens