Download September 2016 - Strathbogie Veterinary Centre

STRATHBOGIE VETERINARY CENTRE LTD
VETERINARY SURGEONS
39 Gordon Street, Huntly, Aberdeenshire, AB54 8EQ,
Telephone: 01466 792627 Fax: 01466 794962
“SERVING TOWN AND COUNTRY”
Newsletter September 2016
Abortion in sheep, its vaccination time!
Abortion costs roughly £85 every time it affects a ewe. Occasionally outbreaks occur
however most farms will have a low level every year. A rate more than 2% can be enough to
indicate an infectious cause. The 3 most common causes of abortion make up over 80
percent. They are Enzootic abortion of ewes (EAE), Toxoplasma gondii, and Campylobacter.
The best way to reduce the chance of an outbreak is biosecurity; the closer to ‘closed’ you
can make your flock, the safer it should be against any number of infectious diseases. Where
abortions do happen it would be sensible to keep aborted ewes (and suspect abortions) away
from the main flock, and remove all aborted material and infected bedding to prevent spread
of disease on your farm. Also, ideally you should be remembering which sheep abort (mark
them), and do not retain any lambs fostered onto them.
The vaccines are guaranteed to last for at least 2 years (Toxo), and 3 years (Enzo), but
realistically are likely to be effective for a lifetime where replacements are routinely
vaccinated. Therefore once divided down (assuming an average of 5 years effect), Enzovac
works out at 42 pence per ewe per year, and Toxovax is 94 pence per ewe per year. And
vaccination reduces the risks to people, particularly pregnant women and those with immune
suppression.
EAE (Enzootic abortion of ewes.): Pregnant women are at serious risk from this disease,
which is still the most common cause of abortion in sheep in the UK. It is spread through
contact with infected uterine discharges and aborted material. It is most commonly
associated with abortions quite close to term (within the last 3 weeks). Live lambs rarely
survive more than a few hours despite supportive care.
It does not result in abortion during the same pregnancy as infection, unless the ewe is over 6
weeks away from lambing. Therefore a lot of the abortions we see are actually due to
infection from the previous year. In these cases last minute injections of Oxytetracycline will
not make much difference. They are helping to reduce shedding, so hopefully reduce spread,
and may increase survival rates of affected lambs. However, with antibiotic resistance
becoming commonplace, you should not be using Oxytetracycline as a routine preventative
treatment for EAE in ewes, only when there is an outbreak.
Toxoplasma gondii: This also carries a risk to people, both to pregnant women and those
that have a suppressed immune system. It is a protozoan parasite, not a bacteria so antibiotics
will have no effect. The parasite has two parts to its life cycle, one half in cats (and other
carnivores such as foxes), and the other in a range of species including sheep. Abortion, or
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STRATHBOGIE VETERINARY CENTRE LTD
VETERINARY SURGEONS
39 Gordon Street, Huntly, Aberdeenshire, AB54 8EQ,
Telephone: 01466 792627 Fax: 01466 794962
“SERVING TOWN AND COUNTRY”
early fetal loss can occur at any stage of gestation and increased returns to service can also be
due to Toxo. Often the highest numbers of barren sheep are the youngest. Typically some
infections will lead to live (sometimes weakly) lambs alongside a mummified fetus. In this
case, because cats and foxes are the most common cause of infection, sheep feed should be
stored in vermin-proof facilities to prevent contamination.
Campylobacteriosis: This occurs particularly where sheep are managed intensively, in
unhygienic conditions. Again abortion is usually either in late gestation, or involves the birth
of week lambs. Once again keeping aborted ewes away from the rest of the flock is the best
way to manage this bug, and pay particular attention to keeping water and feed troughs clean
and free of infection. Treatment options are limited in this case because spread has usually
already occurred. A vaccine can be imported to the UK under license where there is no other
way to minimise spread.
Salmonella: Finally a few Salmonella bugs have been associated with abortion; in some
cases the ewe is simply found dead, with rotten lambs inside the womb. The source of
salmonella is contaminated feedstuffs and water courses; sewage effluent overflow, carrier
cattle and dead animals. Once again, this bug can affect people.
Cattle Pneumonia:
Pneumonia vaccinations are also due soon, every year we are busy in Autumn with outbreaks
of pneumonia and there’s no saying where it will hit next. For those of you with calves at
risk the vaccines can help save thousands of pounds worth of losses. With Rispoval 4 the full
course (2 injections 3-4 weeks apart) needs to be completed before the risk period, which is
generally housing. Most of the intranasal vaccines are a little more flexible in that they only
need to be given once but for best effect should be given before the period of stress starts.
There are a range of vaccines, some more suited to store cattle, mixed from various sources
and others,’ for younger and home-bred calves where the viruses involved shouldn’t be
changing as much from year to year.
Remember attention to cattle sheds is also important while they are empty. Fix that
leaking down-pipe, or hole in the roof. Look at the shed to see if there is anything that can be
changed to improve ventilation, particularly air outflow in or near the roof, without leaving
big holes at cattle height where the prevailing wind can cause draughts. Buildings should also
be the correct size for the number of animals. With cows and young calves roughly 10
metres squared per cow (plus a calf creep) would be a rough estimate, depending on building
design. For older, weaned calves kept in groups, 5/6 metres squared per calf is more
appropriate.
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