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Duncan Gaudie & Iain McCulloch
W
ith the arrival of the new wormer Zolvix
TM
, there has been a lot more discussion of wormer
resistance with clients - and it's difficult to give accurate advice without knowing just what the
local situation is. Very few of our clients have any idea of their resistance status. With this in mind
I decided to offer free pre and post treatment faecal testing to our sheep clients to try to build up
a picture of what levels of problems are around.
Wormer resistance in sheep
We've got around 150 sheep clients in
the practice area ranging from a few pet
sheep, to flocks with 2,000 ewes. Clients
were mailed with invitations to participate
(I followed this by hassling any I saw over
the next few months!) and 30 took part over
this year. Although only a relatively small
number were involved, they ranged from
small flocks of 15-30 ewes up to the largest
with 1,400 - so hopefully were a good
representation of the sheep flocks in our
area. In total 41 groups of sheep were
sampled. All the clients taking part were
sent a pack with instructions for the sampling
intervals, sample pots and a questionnaire
about their usual worming practices.
This wasn't being done strictly scientifically -
I asked farmers to weigh the heaviest sheep
(where they had the facilities) and to dose the
group for that weight and I also asked them
to check the calibration of the dosing gun
(but not all did). The idea was to get a rough
impression of how effective their wormer
was. Some clients marked the sheep that
they sampled so that they could sample the
same ones post treatment. When examining
the faeces I repeated the test to ensure a
good flock average. To allow for any
inaccuracy I considered a 75% egg reduction
to be adequate efficacy (for the purposes
of this study).
The faeces were examined under a
microscope using the standard McMaster
flotation technique, which should give a
sensitivity of 50 epg (worm eggs per gram
of faeces). When examining the faeces
I classified the eggs into three groups:
Strongyle type eggs, Strongyloide eggs
and Nematodirus eggs. I also noted down
any other findings e.g. coccidia, tapeworm
eggs/segments and lungworm larvae.
7
LIVESTOCK MATTERS
WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
S P R I NG F E AT U R E
Polly Gratwick
Penbode Veterinary Group
Veterinary Surgeon
Polly Gratwick
XLVets Practice
Penbode Veterinary
Group, Devon
POL LY GRATWI CK
Most farmers get their worming advice from the
merchants where they buy their wormer, rather than
asking their vet, so often we are only approached
if they perceive that the wormer ‘hasn't worked’.