Gauteng Smallholder Gauteng Smallholder November 2011 | Page 29

ANIMAL HEALTH
All about ticks and how to control them
A
ll Gauteng's livestock
are vulnerable to
various species of
ticks. There are more than 20
different tick species found in
South Africa and most of
them carry diseases that affect
livestock, pets and, some-
times, humans.
The effects of ticks on sheep,
goats, horses and cattle
should not be underesti-
mated, particularly on young
animals. We might think that
the amount of blood loss
caused by a tick would be
negligible. However the
animal is likely to be carrying
many more than one tick and
this has been shown to
cause loss of weight and to
retard growth.
Tick bites also cause
discomfort to the animal and
might even affect its appetite,
which will also affect its
condition. Furthermore, the
bites leave small wounds
which can become infected
and lead to deterioration in
wellbeing.
These wounds also leave the
animal vulnerable to infesta-
tion by screw-worms, which
is very difficult to eradicate.
In the case of horses and
cattle, infestations of ticks can
damage the tail brush, which
might result in the loss of the
ability to wave away flies.
All feedings of ticks at each
stage of their life cycle are
parasitic. Ticks feed only on
the blood of their hosts. The
ticks crawl on to their host
and attach to the skin. They
use a combination of cutting
mouthparts which penetrate
the skin and often an
adhesive or glue is secreted in
the saliva to aid attachment
to the skin.
All ticks spend most of their
life cycle away from their
hosts, hiding in soil and
vegetation. Some ticks crawl
onto vegetation and wait for
their hosts to pass by. The
ticks grab onto the hosts using
their front legs and then crawl
over the skin to find a
suitable place to attach and
feed. Adult ticks of the genera
Amblyomma and Hyalomma
are active hunters and will
run across the ground to seek
hosts that are resting nearby.
The tick has three phases in
its life cycle: larvae hatch out
of eggs, then later moult to
nymphs. Nymphs feed once
and moult in the same way as
larvae. From the nymphal
moult either a female or male
adult emerges. The female
feeds once and lays one huge
batch of eggs. Eggs of all ticks
are laid in the physical
environment, never on the
host. She then dies. The
males may take several small
feeds, mate and then die.
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In some species there is a
different host for each of the
phases. Immature
Amblyomma hebraeum for
example feed on scrub hares
or guinea fowl, while the
adults feed on cattle, sheep,
goats and horses. Some
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