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Cause |
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Effect |
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Prevention |
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Blowfly
Strike |
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The
infestation of the live animal with maggots of
blowflies (green bottles). Common in the soiled
wool around the crutch area or any infected
injury that attracts flies. The maggots produce
enzymes which digest the skin producing large
open wounds. The wound secretions then attract
further flies. Severe cases can result in death
in less than one week. |
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Flystrike
is often concealed by the fleece. Signs of attack
include biting or nibbling infected areas,
lameness and tail wagging. Open wounds cause
severe scarring of the skin which grossly affects
the appearance and handle of the final leather.
In addition, affected areas dye a different
colour to normal areas and render the skin
unusable for leather clothing and goods. |
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To
control flystrike, blowflies must be discouraged
from laying their eggs on sheep. This can be
acheived by dagging and crutching to reduce
soiling, prompt attention to wounds and by
treatment with organophorous dips and selected
pour-ons containing cyromazine, cypermethrin or
deltamethrin. |
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Sheep
Scab |
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Sheep
scab or psoroptic mange is caused by the mite
Psoroptes ovis, which lives on the skin of sheep.
The mites pierce the skin and feed off the fluids
which ooze from the wounds. These wounds, and the
resultant encrusted scabs, cause increasing
irritation and can lead to death. |
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Infested
skin becomes hard, loses texture and often
develops raw patches which result in coarse grain
patterning and scarring on the skin. In the
absence of regular dipping or other treatment,
the incidence of sheep scab and subsequent damage
to skins will increase dramatically. |
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Sheep
scab is a highly contagious disease which spreads
rapidly through flocks, especially at high
stocking densities. Sheep scab can be controlled
by the use of dips containing organophosphate or
synthetic pyrethroids or by injection with
avermectins and related products. |
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Cockle/
Keds |
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Cockle
is the term used in the leather industry to
describe the small hard nodules which form in the
skin following Ked infestation. The nodules are
an inflammatory response of the skin to the
presence and saliva of Keds. Keds are most active
in the cooler autumn/winter months and are more
common on the coarse rather than fine wooled
breeds. |
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Cockle
is first recognised after the wool has been
removed from the skin and appears on the surface
as small firm nodules. Following tanning and
dyeing, these nodules disfigure the leather. Keds
tend to accumulate in the natural folds of the
skin, but in severe cases can spread all over.
Any relaxation in regular dipping regimes lead to
an increase in the incidence of cockle damage.
Lice have also been linked to cockle damage on
sheepskins. |
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Shearing
reduces the Ked population, after which cockle
tends to disappear. Keds and lice can also be
controlled by organophorous dips, certain
synthetic pyrethroids and other pour-on products. |
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| Tick |
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Ticks
adversely affect sheep production through direct
injury and blood loss as well as the transmission
of toxins and disease. Some of the diseases, for
example Lymes Disease, can affect man. Ticks feed
by attaching themselves to the animal and
abstracting blood through needle like mouth parts
causing physical damage to the skin. Ticks are a
regional problem in the UK, with two seasonal
peaks occurring in spring and autumn. |
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Tick
damage on sheepskins in primarily found along the
belly areas or where the fleece is thinner, ie,
legs. Lamb skins are particularly susceptible to
tick damage. Damage to the leather includes the
puncture hole and associated scarring in the
affected area. Secondary bacterial infection of
the "bites" increases the severity of
the damage. |
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Ticks
are a seasonal problem and can be controlled by
dipping or treating affected animals with certain
pour-on products. The major part of the ticks
life cycle is spent away from the host on the
ground, making chemical treatments alone
difficult. |
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Mycotic
Dermatitis |
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Mycotic
Dermatitis (lumpy wool or rain rot) is a
widespread infection of sheep skin caused by the
filamentous bacteria, Dermatophilus colgolensis,
which grows in the outer layers of the skin. The
skin reacts to the infection by forming layers of
scabs which lift away from the skin as the wool
grows. |
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The
organism requires warm, moist conditions and is
most common during wet summers and autumns.
Infections lead to the hair follicles becoming
enlarged and distorted resulting in a pinhole
appearance on the leathers surface. In addition,
wool growth may be stunted and quality down
graded. |
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Dipping
with a 5% Zinc Sulphate solution will treat
Mycotic Dermatitis infections. Zinc Sulphate
cannot be mixed with organophorous (OP) dips, but
at least one non-OP dip (Bayer’s Bayticol)
is licensed specifically to be mixed with Zinc
Sulphate. |
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