Contagious pustular dermatitis (Orf,
scabby mouth, contagious ecthyma).
The cause is a pox virus (genus Parapoxvirus) which can remain
infective for many months in dried scabs on pasture. Orf is a
zoonosis (transmissible to humans).
Contagious pustular dermatitis virus most commonly results in
proliferative lesions at the coronary band and along the gum
margins, being particularly severe in artificially-reared lambs
less than two months-old. Morbidity can be high but mortality
in uncomplicated cases is low. Lesions persist for some two
to four weeks then slowly regress. Disease in the flock
generally persists for six to eight weeks.
Scabs progress to large proliferative wart-like
structures which bleed profusely, following trauma to their
Large scabs are often present at the commisures of the lips and
along the gum margins surrounding the incisor teeth. Much
less commonly, lesions may involve the hard palate and tongue.
Typically, virus rapidly spreads within a group of orphan lambs
sharing the same feeding equipment. In sucking lambs lesions
frequently transfer to the inner aspect of the ewe's teats; this
area of the teat having been traumatised by the lamb's incisor
teeth permits entry of virus. These teat lesions are painful
and the ewe typically will not allow the lambs to suck.
Mastitis, occasionally gangrenous in nature, may follow the
development of such teat lesions.
Contagious pustular dermatitis virus and Staphylococcus
aureus may act together to cause severe facial dermatitis,
which appears as sharply-demarcated areas extending up 8 cms from
the muzzle and involving the lower lip with scab material also
palpable within the hairs extending for a further 2-3 cms from the
periphery of the visible lesions. The skin is oedematous,
with exudation and superficial pus accumulation forming hard scabs
separated by deep fissures. Removal of the scabs reveals a
deep bed of exuberant granulation tissue.
Contagious pustular dermatitis virus and
Staphylococcus aureus may act together to cause severe facial
Severe facial dermatitis caused by contagious
pustular dermatitis virus and Staphylococcus
Contagious pustular dermatitis virus and Dermatophilus
congolensis may act together to produce large granulomatous
masses extending 4 to 8 cms proximally from the coronary band often
referred to as "strawberry footrot". These lesions bleed
profusely when traumatised. Typically, strawberry footrot
lesions only affect one leg and are more commonly seen
in weaned lambs recently moved onto stubbles. While lesions
are severe in individual lambs, the morbidity is generally
low. Healing takes many months.
The possibility of foot and mouth disease must not be overlooked
but orf presents with large bleeding scabs rather than
Virus can be demonstrated by direct electron microscopy of fresh
Treatment is largely unsuccessful, except for lambs with
secondary bacterial infection of scabs which show a good response
to intramuscular procaine penicillin injections for five to seven
A good response to intramuscular procaine
penicillin injections for secondary infection of orf lesions (see
Disease is introduced into a flock by carrier sheep with no
obvious skin lesions. Infection can remain viable in dry scab
material for many months.
Control, by using scarification with a live vaccine,
is routinely undertaken in many flocks in the UK. Vaccine
must never be used in a clean flock. The timing of vaccination is
approximately 6 weeks before the anticipated occurrence of
disease. Care must be exercised during handling the live
vaccine as it is affected by high temperatures and inactivated by
Dermatophilosis (lumpy wool, mycotic
dermatitis, rain scald)
Dermatophilosis is a common skin infection of sheep world-wide
but is of minor significance in the UK where there is little high
quality wool production. The disease is caused by
Dermatophilus congolensis which is spread during wet
conditions and close contact during gathering etc.
In the UK, dermatophilosis is encountered along the dorsum in
short-wooled breeds, such as the Suffolk and Border Leicester,
where it causes serum exudation and scab formation at the base of
the wool fibres which then slowly grow out. Dermatophilosis
is usually encountered during those summers when there
has been wet weather for three to six weeks after shearing.
Occasionally, scabs attract blowfly strike. Discrete 3 to 5
mm diameter "bottle-brush" lesions are often found around the
muzzle and on the margins of the ears of poorly-thriven sheep.
Extensive skin lesions caused by dermatophilosis
are rare in the UK.
Dermatophilosis more commonly presents as discrete
3 to 5 mm diameter "bottle-brush" lesions on muzzle and margins of
the ears of poorly-thriven sheep.
"Bottle-brush" lesions on
Treatment is rarely indicated in the UK but rams intended for
sale are sometimes treated to prevent skin lesions re-growing black
wool, which is considered a defect at sale. Procaine
penicillin injected intramuscularly for three consecutive days
effects a cure but it may take several weeks for the scabs to be
shed from the growing fleece.
Procaine penicillin injected intramuscularly for
three consecutive days effects a rapid cure.
plochteach, alveld, facial eczema)
Typically, white-faced lambs two to six months-old are affected
during the summer months. In sheep, photosensitisation occurs
either as a primary condition or secondary to liver damage .
Primary photosensitisation follows ingestion of photodynamic
agents, for example hypericin from St. John's Wort (Hypericum
Initially, affected animals are dull and attempt to seek shade.
The ears in particular are affected and become swollen and
pendulous. The face, eyelids, lips and lower limbs may
also become oedematous. There is frequent head-shaking and
often self trauma to the head by rubbing against fence posts or
kicking at the head with the hind feet. Necrosis of the ear
tips develops within a few days which give a "curled-up"
The ears, face, eyelids, and lips become
In severe cases, the ears may be
Affected sheep must be removed from pasture and confined in dark
buildings to prevent further exposure. Corticosteroids are
helpful during the early stages to reduce the associated oedema.
Other symptomatic treatments include topical antibiotic powders and
fly control preparations.
Primary photosensitization occurs sporadically and the cause is
often not determined.
Periorbital eczema is a common skin condition when sheep have
too little space allowance at feed troughs.
Periorbital eczema is more common when sheep have
too little space allowance at feed troughs.
Affected sheep have swollen and painful eyelids blocking vision
in that eye.
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 misadventure. Provide adequate
space at feed troughs (450 mm per sheep).
Alternatively, use a "snacker" sheep feeder.
Space allowance is not a problem when feeding sheep
with a snacker.
Horned sheep must be checked regularly for in-growing
horns. Horns contacting the skin must be removed.
In-growing horn - immediate attention is
Horn tip removed revealing bone remodelling caused
by pressure from the in-growing horn.