Bluetongue Vaccination

A number of options exist for the control of Bluetongue (BTV) this summer.  Adult cows and sheep will have been vaccinated, bigger issue is how best to protect this years crop of calves and lambs.  Midge activity readily increases at temperatures above 14C, and we certainly have had temperatures in this region on many occasions.  The threat of BTV arriving will rest on the chance of infected midges coming in from the continent or parts of the UK thought to be more at risk, and the movement and re-location of infected animals.  All reports indicate that vaccination is a very effective way of controlling disease, so the Scottish adults will all be taken care of.  At a recent conference it became clear that in Holland in 2008, although the adults were protected by vaccination, their calves and lambs were at risk and did develop disease.  This situation developed when vaccine supplies only became available after most young animals had been turned out without vaccination.  The cows which were then subsequently vaccinated were protected, but not the calves.

 So it seems the best way to protect calves and lambs is when they are old enough for the vaccine to be used.  Different vaccines have different start up ages.  One popular option has been to boost the cows using the Merial vaccine now, and start the young calves on Intervet Bovilis BTV8 at 4 weeks of age and then again 3 weeks after.  These herds will be fully vaccinated over the summer and on annual spring boosters.  This situation will not suit all, but best advice would be to try and vaccinate calves and lambs before the early summer to provide protection when it is needed.  Not easy I know but if we can be of any help in figuring out a vaccination strategy please give us a call.

Unless it is absolutely necessary try to avoid the following when planning vaccination - we want to try and get the best out of the vaccinations, so try to avoid:

•  Combining vaccination with dehorning/castration
• Vaccinating when housing/vaccinating for pneumonia in the autumn
• Handling cow groups at mating just to vaccinate calves
• Delaying vaccination till the risk period is over - say from now till October.

(RA)

BTV Vector Control

While vaccination remains the only way to protect livestock from BTV8, using an insecticide to reduce midge numbers can help cut the risk of virus transmissions, and also reduces the numbers of nuisance flies on the cows, so you will see less cases of summer mastitis in dry heifers and autumn calving beef cows.  In addition it will also reduce the incidence of New Forest Eye, again usually confined to young cattle.  We recommend the use of Butox SWISH to control adult midge numbers.  A standard dose applied along the backline gives good body coverage - vital to control BTV8, as midges like to attack and bite the exposed areas on the legs and belly.  You must start early in the season to control the adult midge population, this reduces the breeding pool and makes the chances of infected midges biting cattle much less.  The control of midges using SWISH will be very important in cattle too young to vaccinate or in those cattle waiting completion of a vaccination course.  (RA)

Calf Diseases

Good springs like this year usually mean good calf health, and certainly calf scour has hardly been reported.  However this year we have seen some peculiar patterns of disease in very young calves.  Affected calves on many farms have died within 2 days of birth, cause of death being severe blood poisoning and/or acute navel infections and pneumonia.  In virtually all cases the calves have been born easily and thought to be well bonded with their mothers.  The one consistent feature has been that all calves have failed to absorb any of the protective antibodies from their colostrum.  This may be due to poor quantity of colostrum, poor quality, delay in suckling, combination of all 3, or some other as yet unknown blocking action?  It does re-enforce the need for calves to get adequate colostrum to help protect against the simple infections seen in calving sheds. 

We have also seen deaths in young calves due to Blackleg, in geographical areas not considered at risk before.  In any cases of sudden un-explained deaths in young calves it is always best to have a full post mortem done.  For outbreaks of Blackleg, double vaccination with Bravoxin 10 will offer best control. 

Also noted in the Edinburgh area is an outbreak of calf deaths with mortality approaching 10% in a suckler herd.  All calves have suffered from a bleeding disorder, any affected have died. As yet no cause has been identified.  It may be a toxic condition or an unusual presentation of BVD. If you are concerned about a similar condition in your calves then contact the practice without delay.  At Kelso we have seen occasional calves suffering from a similar condition over the last 3 years, but not at this level of disease.  A diagnosis was never established. (RA) 

FlockCheck Reminder

FREE ABORTION BLOOD TESTING SERVICE - Intervet SP are currently funding a complementary diagnostic blood test to establish if enzootic abortion or toxoplasmosis is present on your farm.  With the lamb market enjoying a much deserved buoyant trade it is vital to minimise lamb losses by exploring any causes of abortion or high barren numbers in your flock. It can be difficult to establish abortion causes during a busy lambing spell and this is an opportunity to blood test 8 sheep that have aborted, failed to lamb or failed to hold to the tup. If you have vaccinated for any of these diseases then the blood test is not suitable.  It is possible to add screening for other diseases such as tick borne fever, but the lab costs for this disease are not included.  The lab fees for EAE and Toxo are covered, and if you give us some prior notice and flexibility we can let you know when we are in your area and this way we can keep the visit fee down. (RA)

New Animal Welfare Management Programme

Deadlines are tight for the revised Animal Welfare Programme - applications must be received by Friday 15th May 2009, and producers must work with their vets to agree a choice of those actions and produce an agreed plan by Tuesday 30th June 2009.  All Scottish IACS-registered businesses should have a copy of the new application guidance. 
"The aim of the option is to support livestock producers to adopt and continually improve high standards of animal welfare over a 5 year programme. The aim of the option is to assist in reducing common endemic diseases on your farms, make significant improvements to the welfare of your livestock and support the economic viability of your business."

Compulsory elements are a welfare review, welfare management plan, monitoring and benchmarking.  Then - a minimum of 3 specific actions to improve welfare.  These include biosecurity, Johne's control, sheep scab control, lameness, BVD control, and liver fluke control. If you are currently involved in these actions then you will be already ticking many of the boxes. Other options will require much more vet input and as such vet costs will increase, but the end result improvements should be more of a driver than support payments. 

Health planning has brought enormous improvements to many farms and is without doubt an essential tool to improve animal health and productivity, and as such farm profitability.  If you need further advice on the options available please contact your regular veterinary surgeon. (RA)

Sudden Deaths in Growing Lambs

The 3 major causes of sudden death in young growing lambs in the next month will be:

• Pulpy Kidney
• Nematodirus
• Pasteurellosis

As different treatment/management protocols are required for the control of each condition it is important that an accurate diagnosis is reached by submission of carcases for examination.

Pulpy Kidney is a common, rapidly acting and usually fatal disease of sheep of all ages caused by a toxin produced by a Clostridial bacterium.  The disease occurs most frequently in well grown lambs between 4 and 10 weeks of age, or fattening lambs between 6 months and 1 year old, associated with a change of diet such as movement onto silage aftermath or Brassica crops.  Pulpy kidney is also common in ram lambs and shearlings as they are prepared for sale.  Usually the best lambs are affected first.

Early and correct vaccination of lambs is important in controlling the disease.  Sheep farming had become untenable in many parts of the UK before the development in the 1950's of the first multi component clostridial vaccines.  While modern vaccines provide excellent protection against the important Clostridial diseases of sheep, many flocks are improperly vaccinated or not vaccinated at all.

For a sheep to be properly vaccinated it must be vaccinated in accordance with the vaccines data sheet.  In the case of Ovivac-P+ this would be 2 doses of a 2ml dose given under the skin of the neck 4-6 weeks apart.  Lambs can be vaccinated from 3 weeks of age even if the ewes have received Heptavac P/Covexin pre-lambing.  The circulating antibody in the lambs derived from the colostrum does not affect vaccine response in the lamb if administered after 3 weeks of age.  It is important that vaccine after purchase is stored in the fridge and vials once opened are used within 24 hours.  It is equally important to ensure that needles are changed regularly and a needle steriliser system is used to prevent injection site abscesses. (DT)

Nematodirus is an important cause of scour, ill thrift and death in lambs during the spring and early summer.  The risk of nematodirosis exists whenever susceptible young lambs are turned onto pasture which was used for young lambs during the previous 2 years.  It is impossible to provide specific advice about the best timing of preventive management.  The risk of a mass hatch of Nematodirus coinciding with the presence of grazing lambs can be predicted on the basis of weather data and local knowledge of the current disease status.  Where a risk exists lambs born late January and February may require treatment by mid-April and again in mid-May, while late March and April born lambs should be treated in mid-May and again mid-June.

When dosing for Nematodirus a white drench should be used as no resistance has been identified.  No wormers have prolonged activity against Nematodirus and injectable Cydectin has a poor effect against this worm. (DT)

Coccidiosis in general only occurs as a primary problem when stressed animals are exposed to large numbers of Coccidia eggs in a heavily contaminated environment.  Most outbreaks occur in 3-8 week old intensively managed housed lambs but outbreaks also occur in outdoor lambs in cold wet springs when grass is scarce.  Again it is important to gain an accurate post mortem diagnosis before initiating treatment. (DT)