The cause is a pox virus which can remain infective in the
environment for many months in dried scabs. Contagious pustular
dermatitis virus (Also referred to as, CPD, Orf, Scabby Mouth,
Contagious Ecthyma) most commonly results in proliferative lesions
following trauma of the coronary band and lips/gums being
particularly severe in artificially-reared lambs less than two
months-old. Outbreaks of CPD may occur within 10 to 14 days of
pasture change especially onto those pastures which contain
thistles, gorse etc. or stubbles which cause superficial trauma to
the lips/mouth. Contagious pustular dermatitis is a zoonosis (can
affect man) and precautions are necessary when handling suspected
Fig 1: Contagious pustular dermatitis virus most
commonly results in proliferative lesions following trauma of the
dermatitis virus most commonly results in proliferative lesions at
the hoof/horn junction and on the lips The proportion
of the flock affected can be high but mortality in uncomplicated
cases is low. Lesions persist for four to eight weeks then slowly
regress. Initial papule and vesicle stages are rarely observed.
Scabs progressing to large proliferative wart-like structures,
which bleed profusely following trauma to their base, are the more
common presentation. Large scabs are often present at the commisure
of the lips and along the gum margins surrounding the incisor
teeth. Much less commonly, lesions may involve the hard palate and
It the UK, virus rapidly
spreads within a group of orphan lambs sharing the same feeding
equipment. In sucking lambs lesions frequently develop on the
medial 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 will typically not allow
the lambs to suck. Mastitis, occasionally gangrenous in nature, may
follow the development of CPD teat lesions.
Fig 2: CPD 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".
Fig 3: Contagious pustular dermatitis is a zoonosis
(can affect man) and precautions are necessary when handling
dermatitis virus and various bacteria, including Staphylococcus
aureus, may act together to cause severe facial dermatitis
which appears as sharply-demarcated areas on 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 serous exudation and
superficial pus accumulation with adherent straw and other foreign
material which may become desiccated forming hard scabs separated
by deep fissure. Careful removal of the scabs reveals a deep bed of
exuberant granulation tissue.
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 is
more commonly seen in weaned lambs recently moved onto stubbles.
While lesions are severe in individual lambs, the
proportion affected is generally low.
Fig 4: Contagious pustular dermatitis virus and
various bacteria may act synergistically to cause severe facial
dermatitis. (See Fig 5 for treatment response)
Fig 5: Secondary bacterial infection of scabs show
a good response to either intramuscular procaine penicillin or
oxytetracycline injections and topical oxytetracycline spray for
three to five consecutive days (Same lamb as Fig
Fig 6: Veterinary examination is necessary because
not all facial lesions are caused by CPD
The diagnosis of CPD is based
upon the finding of large proliferative lesions around the lips and
nostrils of growing lambs. Virus can be demonstrated at veterinary
laboratories by direct electron microscopy of fresh
Early lesions of CPD are
readily distinguished from foot and mouth disease and Bluetongue
but farmers must always consult their veterinary surgeon if they
are in any doubt.
Treatment is largely
unsuccessful except for lambs with superficial secondary bacterial
infection of scabs which show a good response to either
intramuscular procaine penicillin or oxytetracycline injections and
topical oxytetracycline spray for three to five consecutive days.
Protective clothing and gloves must be worn when handling affected
sheep because of the zoonotic risk.
Fig 7: In sucking lambs lesions frequently develop
on the medial aspect of the ewe's teats; this area of the teat
having been traumatised by the lamb's incisor teeth permits entry
Disease is introduced into a
flock by carrier sheep with no obvious skin lesions. Infection can
remain viable in dry scab material in buildings for many months and
is the likely reason for persistence of infection from year to year
on the same premises. Thorough cleaning and disinfection of lambing
accommodation may therefore help to break the usual annual
appearance of disease.
scarification with a live vaccine proves difficult to quantify but
is routinely undertaken in many flocks in the UK. Vaccine must
never be used in a flock with no history of CPD. Vaccination is by
scarification of the inner thigh in lambs and the axillary region
in ewes. 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 disinfectants.
Fig 8: Gangrenous mastitis following CPD lesion on
dermatitis is a significant problem in orphans lambs and other
ill-thriven lambs, CPD is less of a problem in well-fed,
well-thriven stock. The vaccine is inexpensive but the procedure is
time-consuming and there is the risk of human infection.