Download Clostridial Disease Enzootic abortion

It is well know that prevention is better than cure and the best way to
protect your flock from infectious diseases is to vaccinate, in
addition to employing good biosecurity measures. Which
vaccinations to use will depend on your flock’s current disease
status, buying in policy and biosecurity protocol. This can be
discussed with your vet at your flock health review. Some of the
common infectious diseases that we can vaccinate for are discussed
below. It is vital that vaccines are stored and administered correctly.
If you are in any doubt contact us for advice.
Clostridial Disease
This is caused by the Clostridial group of bacteria and includes conditions such as tetanus, botulism, pulpy
kidney and black leg. Clostridial bacteria are ubiquitous in the environment and produce spores which can persist
for long periods of time in soil, becoming active again if the correct conditions arise. Outbreaks of disease are often
triggered by factors such as changes in management, parasitic activity and traumatic injury. Once infected animals
deteriorate rapidly and are often found dead before any clinical signs are seen, making vaccination even more
important in control.
Vaccine: Heptavac P
This protects against all the common causes of Clostridial disease as well as Pasteurella (a cause of pneumonia).
The initial course is 2 injections 4-6w apart. Boosters should then be at least yearly; in areas with a high incidence
of disease 6 monthly boosters may be required. Boosters should ideally be given to ewes 4-6 weeks prior to
lambing so that protection can be passed onto lambs via the colostrum. When handling sheep, stress should be
avoided, particularly during the later stages of pregnancy when there is a risk of inducing abortion and metabolic
disorders.
Enzootic abortion
Chlamydophila abortus is the bacteria responsible for enzootic abortion. In unprotected sheep it spreads to the
uterus and placenta during pregnancy killing the lambs and causing abortion. The aborted material is highly
infectious to both sheep and people (Chlamydophila abortus can also cause serious illness in pregnant women and
so they should avoid contact with lambing ewes). Infected sheep may also give birth to normal lambs that are
carriers of the disease and so contribute to its spread throughout the flock. Sheep can become infected at any time
but the disease will only become apparent at lambing. Replacement stock are an important potential source of
infection in a clean flock. The disease is best diagnosed on aborted foetuses and placenta but exposure to the
bacteria can also be seen on blood samples from ewes.
Vaccine: Enzovax
Ewe lambs intended for breeding may be vaccinated from 5 months of age. Shearlings and older ewes should be
vaccinated during the 4 month period prior to mating. Vaccination must take place at least 4 weeks before mating.
Re-vaccination is recommended every 3-4 years depending on farm management practices and conditions.
Toxoplasmosis
Toxoplasma gondii, a small protozoan parasite, is another common cause of abortion in sheep. Cats are the
definitive host of the parasite and infected cats shed toxoplasma oocysts (eggs) in their faeces. These oocysts are
very resistant in the environment and can persist for 12-18 months. Sheep may become infected by ingesting
oocysts from the pasture or in feed. Once ingested the parasite multiplies and persists in tissue cysts in the heart,
brain and muscle. If a sheep is infected during pregnancy the parasite damages the foetus and placenta and if in
early gestation this causes abortion. If infection occurs later on in gestation still born, mummified or live but weak
lambs may be seen. Toxoplasma may also be transmitted to humans from the ingestion of oocysts or from eating
undercooked meat containing parasite tissue cysts. Pregnant women and immuno-compromised individuals are
major risk groups and should avoid contact with ewes at lambing time.
Vaccine: Toxovax
Animals should be given a single dose at least 3 weeks prior to mating. Ewe lambs, where it is intended to breed
from them, may be vaccinated from 5 months of age. Shearlings and older ewes should be vaccinated during the 4
month period prior to mating. Boosters should be given after 2 years at least 3 weeks prior to mating.
Schmallenberg Virus
Schmallenberg Virus, as our newest infectious disease, has created many challenges over the past couple of
years. It was first detected in Germany and the Netherlands but has since been found in many European
companies including England, Wales and Scotland. It is spread by midges and causes foetal deformities including
twisted spines and fused joints. As far as we know it is not transmitted directly between animals. This means that
even if a flock has experienced clinical cases in previous years a proportion of the flock is still likely to be
susceptible making vaccination an important tool in control.
Vaccine: Bovilis SBV
A single dose from can be given from 4 months of age with immunity taking 3 weeks to be fully acquired. The
vaccine must not be given concurrently with any other vaccine or to pregnant animals.
Footrot
This is caused by a bacteria called Dichelobacter Nodosus which is found in the interdigital skin and hoof horn of
ruminants. It does not persist for long periods off the animal (10-14 days) so in theory should be easy to control! If
treated early it responds well to topical and injectable antibiotics. Infected feet should not be pared as this delays
healing. If not treated infection can spread into the hoof leading to separation of the horn from the underlying
tissue. This happens most rapidly in warm, moist conditions leading to the characteristic odour and discharge.
There are 5 key points for footrot control:
1) Prompt treatment
2) Separate infected animals
3) Record all cases so the persistent offenders can be identified
4) Cull persistent offenders
5) Vaccinate
Vaccine: Footvax
Vaccination is very useful in control as it can be curative as well as preventative. The initial course comprises two
doses 6 weeks apart by subcutaneous injection on the side of the neck 2-3 inches behind the ear. This should be
followed by boosters every 6 months prior to the risk period (more frequent boosters may be required depending on
individual flock requirements and the climatic conditions). Sheep should not be vaccinated within 6-8weeks of
shearing or in the period of 4 weeks before lambing to 4 weeks after lambing. Cydectin wormer should not be used
in any animals previously vaccinated for footrot.
Orf
Orf is a viral disease of sheep which causes scabby lesions most commonly around the mouth and nostrils but also
occasionally on the teats of nursing ewes and the lower legs of lambs. Infection normally resolves over 4-6 weeks
but is associated with poor growth rates and can in some cases cause extensive lesions to the face and mouth.
Infection will only establish where the skin or gums have been damaged so rough food or pasture may predispose
to infection. The virus is not capable of surviving winter outside but can persist in buildings for many years. Humans
can also catch Orf which causes localised red swellings and can be very painful. Topical antibiotics can be used to
reduce secondary infection and vaccines can be used to help in its control.
Vaccine: Scabivax
This vaccine is a live virus vaccine so should not be used on farms where Orf is not a problem. It is also important
not to contaminate sites other than the vaccine site with the vaccine e.g. mouth, feet or superficial wounds.
Immunity develops within 4-8 weeks of vaccination and is protective against severe lesions for 12 months; although
not fully protective against reinfection the disease in a vaccinated animal will be less severe and shorter lived.
Ewes should not be vaccinated less than 7 weeks before lambing and ewes that are vaccinated prior to lambing
should not be moved to the lambing shed until sufficient time has passed for the scabs caused by the vaccine to
drop off as these will contain the virus (minimum 7 weeks). Ewes with unvaccinated lambs at foot are best to have
their vaccination delayed until after weaning except in an emergency. No protection is passed to lambs in
colostrum so lambs may also require vaccination and this can be done from birth. The vaccine is capable of
causing a skin reaction in humans so should not be used by immunosuppressed individuals. It is strongly
recommended that effectiveness of vaccination is assessed 7-10 days after vaccination by examining a selected
group and checking that the vaccine has ‘taken’ (pustules have developed at the vaccine site). Routine disinfection
of housing is also vital in control of Orf.