STRATHBOGIE VETERINARY CENTRE LTD
VETERINARY SURGEONS
39 Gordon Street, Huntly, Aberdeenshire, AB54 8EQ,
Telephone: 01466 792627 Fax: 01466 794962
“SERVING TOWN AND COUNTRY”
Newsletter July 2015
A sheep special this month! But first just a note to all cattle keepers that if
you’ve any queries about BVD please don’t hesitate to phone. The scot EID
centre which is based in Huntly is also useful where there are niggling issues.
They have a website and you can call them during office hours.
Two sheep diseases to talk about this month: the one thing they have in
common is that there is no treatment for them. Therefore once they are in
your flock it can be difficult to clear them.
Jaagsiekte; OPA (Ovine, pulmonary adenocarcinoma): is an infectious virus
which causes fatal lung tumours in sheep. After infection, the disease can be
silent for 5 months to 3 years, and most commonly starts to show at 3-4 years
of age. By this time, a large part of the lung is damaged by tumour. By the end
of the clinical course, sheep show emaciation, dyspneoa, lacrimation and most
importantly lots of watery discharge.
There is no reliable test for OPA in live sheep, but the ‘wheelbarrow test’ is
fairly accurate for late stage cases. This is where frothy white fluid pours out
of the sheeps’ nose when it is lifted by its hind-legs. These sheep should be
culled as they will be a major source of infection. On post mortem
examination, lesions are recognisable.
Keeping sheep in close contact, for example during the winter / at lambing
time is a big risk factor for spread of the disease, so to help reduce spread
make sure to minimise the stocking density at housing, and maximise
ventilation, or try to reduce the time that sheep are housed. Jaagsiekte is
apparantly less commonly diagnosed in the hill flocks of north, and west of
Scotland, Cumbria and the Lake Distract so buying in from these areas may
help reduce the risk of buying more in. If these are more likely to be free of
Jaagsiekte, keeping the new animals separate from the rest of the flock for as
long as possible will extend the productive life of the flock. It is also thought
that some animals have a genetic immunity to it, so if you are sure to remove
the offspring of ewes that die of Jaagsiekte, you may be able to minimise levels
of the disease.
STRATHBOGIE VETERINARY CENTRE LTD
VETERINARY SURGEONS
39 Gordon Street, Huntly, Aberdeenshire, AB54 8EQ,
Telephone: 01466 792627 Fax: 01466 794962
“SERVING TOWN AND COUNTRY”
Newsletter July 2015
CLA; Caseous Lymphadenitis: A bacterial infection which causes abscesses in
the lymph nodes of sheep and goats, which then spread to most internal
organs including the lungs, spleen, kidneys, and liver.
Transmission is by contact with open wounds, so directly between sheep
during close confinement, or via contaminated shearing equipment, or fences
etc. Tups that fight are prone to spread infection through lesions on their
heads.
There is a blood test for this disease, so it can be removed from a flock with
regular flock testing, and culling of affected cases. There is no effective
treatment, as although antibiotics would kill it, they tend not to penetrate the
abscesses very well. It is not ideal to lance the abscesses as this only leads to
further contamination of the environment and risk of spread.
Prevention can be maintained with biosecurity; purchased animals are the
biggest risk for bringing infection into a naive flock. New animals should be
isolated for at least 2 months before introduction to the flock, and should be
inspected for signs of CLA on purchase. Blood sampling imported animals can
also be carried out. Attention must be paid to the use of shared shearing
equipment and handling facilities that might spread infection between flocks.
These should be disinfected thoroughly between flocks.
Vaccination is not an effective way of clearing infection from a flock. It will
only reduce the incidence. It is used where there is a lot of CLA (America and
Australia), but not really in Europe. The only effective way of clearing the
disease from a flock is a strict test and cull policy, with testing repeated
regularly until the flock is clear.