Page 477 - The Veterinary Laboratory and Field Manual 3rd Edition

414 Susan C. Cork

evidence of ectoparasites (especially mites). Liver When did the lesions first appear? Check
disease and malnutrition (for example, vitamin the diet and other management parameters.
A deficiency) may increase the susceptibility of What other clinical signs were apparent?
livestock to ectoparasites as well as resulting in 2 Perform a thorough clinical examination.
poor skin and hair condition. Endocrine disorders Examine a selection of animals in a group
such as an underactive thyroid gland (hypothy- and look for early and developed lesions. The
roidism) may be associated with bilateral (and scabbed over lesions may only be evidence
systemic) hair loss, weight gain and susceptibil- of self-trauma and secondary infection. Look
ity to cold. In most cases this condition will only for small raised papules and other primary
occur sporadically. Prolonged systemic diseases lesions and also look carefully for the pres-
and, in sheep, specific conditions such as scrapie ence of ectoparasites. Examine the animals
may also need to be considered as a cause of poor for other signs of disease, for example, mal-
coat, disrupted wool growth and skin damage. In nutrition, liver damage and so on.
any case of skin disease, it is essential that a good 3 Collect samples of hair and/or wool. It may
case history is taken and that the animal(s) is/are be necessary to take several skin biopsies
given a through clinical examination to look for to represent the primary lesions and skin
underlying causes. scrapings or hair samples for microbiologi-
cal examination. Collect ectoparasites for
1 Take a full clinical history. How many animals identification. If required, skin biopsy mate-
are affected? What age group is involved? rial should be submitted to the laboratory in

Table 10.7 Terms used to identify skin changes.

description
Diffuse (widespread) lesions
Scales Unbroken skin surface, dry, flaky skin
Excoriations Traumatic, abrasions and scratches
Fissures Deep cracks
Hyperkeratosis Excessive overgrowth of dry horny thickened skin, skin surface
unbroken
Eczema Red itchy skin, weeping dermatitis, scabby disruption of the surface
Discrete (well defined) lesions
Vesicle (bullae, blister) Fluid filled blister, 2 mm diameter, superficial
Pustule Pus filled blister, will rupture, 2–5 mm diameter
Wheals Swollen and reddened areas, transitory
Papules Elevated, inflamed areas, tend to point and rupture
Nodules Elevated, solid 1 cm diameter (variable), in acute and chronic stage,
surface unbroken
Scab Crust of coagulated serum, blood, pus and skin debris raised above
skin surface
Pyoderma May become diffuse, secondary (occasionally primary) infection of the
skin and/or follicles

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