Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

Clinical Examination of the Skin
Area of infested skin
Alopecia and thickened
crusty skin
Figure 4.3 Chorioptic mange mite infestation of the tail
head. Similar lesions occasionally involve sarcoptic mange
mites.
Psoroptic mange is rare in the UK (5% of cases), but
large numbers of cases occur elsewhere. Psoroptes
natalensis, the surface living causal mite, is associated
with extensive thickening of the skin, pruritus
and hair loss over the shoulders, hindquarters and
perineum. Thickened crusty skin is seen in chronic
cases which may be in very poor condition.
Demodectic mange is often asymptomatic in cattle,
but the mite can be found in nodules in the skin covering
the thorax. Alopecia involving the skin of the
neck but with no pruritus has been found in animals
infested with the cattle itch mite Psorobia bovis.
Diagnosis of mite infestation is based on the clinical
signs associated with each mite and identification
of mites in skin scrapings.
Ticks
Ixodes ricinis, Dermacentor reticulatus and Haemaphysalis
punctata are found in parts of the UK.
The ticks may be found on animals imported from
these areas and produce particularly severe symptoms
in animals which have had no previous exposure
to them. The ticks are visible to the naked eye and
can be identified under the microscope. Heavy tick
infestation can lead to anaemia, and skin lesions on
the lower parts of the body are seen; there are small
areas of granulation tissue and possibly a hypersensitivity
reaction. Ticks carry a number of diseases including
babesiosis, tick-borne fever and Lyme
disease.
Blow-fly strike
This is initiated by the egg laying of blow flies, including
Lucilia sericata or Phormia terraenovae, whose
larvae infest soiled skin especially in warm weather.
Blow-fly strike can occur anywhere on the body, including
the frontal sinuses exposed by horn removal.
The larvae, which are readily seen with the naked
eye, penetrate the skin and the deeper body tissues.
Adjacent areas of skin may show signs of necrosis.
Larvae may also enter the natural orifices of the
body, including the anus.
Bacterial skin disease
Superficial trauma, heavy contamination, damp and
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