Held last month, the Tullamore Farm Virtual Series featured MSD’s veterinary advisor, Sarah Campbell, who spoke with the Irish Farmers Journal’s Darren Carty, covering a range of animal health issues facing sheep farmers.
Clostridial disease
On the night, Sarah highlighted the importance of vaccination against clostridial diseases. This is particularly important given that clostridial bacteria are a common cause of death in both lambs and sheep.
Clostridial infections of sheep and cattle are caused by a group of bacteria that exist in soil, on fields, within buildings and even in the tissues and intestines of cattle and sheep.
However, protection can be achieved by using a broad-spectrum vaccine to provide animals with the necessary antibodies to combat all the strains of clostridia.
Tribovax 10 is a low dose clostridial vaccine offering cattle and sheep producers the broadest available protection against clostridial bacteria.
Orf
Touching on the topic of Orf, Sarah advising sheep farmers to use preventative control measures against Orf, including the vaccination of the flock with Scabivax® Forte to reduce the risk of contracting the virus.
Abortion
If farmers are having issues with abortion in their sheep, Sarah recommended that farmers get a diagnosis through submitting the foetus and placenta to a lab for analysis. If this is not possible, blood samples can be taken by a vet.
Toxoplasma gondii is the most commonly diagnosed cause of ovine abortion in Ireland and in the most recently published report, was diagnosed in 26% of samples submitted to the regional veterinary laboratories.
Chlamydophila abortus is the second most common cause. Other less frequently diagnosed causes include leptospirosis, campylobacteriosis, salmonellosis and listeriosis.
Once a diagnosis has been confirmed, a control strategy can be planned. This will often involve vaccination against either toxoplasmosis, enzootic abortion (EAE) or both.
For further information on any of the products discussed in this video contact your veterinary advisor or check out the Bovilis website for further product information.
Vaccination as part of the strategy to control footrot has meant ewes with more milk, better lamb thrive and more lambs sold for Roscommon farmer Joseph Kennedy.
On the advice of his veterinary practitioner, Donal Flynn of All Creatures Veterinary Clinic, Joseph introduced vaccination as part of a strategic footrot control plan five years ago.
“I had a serious lameness problem. The labour and time involved in treating lame sheep was very high. Fertility in affected sheep wasn’t what it should be and I had regular problems with ewes with twin lamb disease,” said Joseph.
There has been a big reduction in lameness and the use of antibiotics to treat lame sheep. Overall, there has been a massive improvement in sheep productivity.
Joseph runs a flock of 80 ewes and 25 replacement ewe lambs at Weakfield, Co. Roscommon.
The commercial flock of Rouge/Texel crosses has scanned at an average of 2.2 in recent years. He is also a pure-bred Rouge breeder and there is strong local and regional demand for his rams.
Campaign
Joseph is participating in a national information and awareness campaign run by XLVets on the benefits of vaccination as part of a strategic plan to control footrot. The campaign is run in association with MSD Animal Health, manufacturers of the only vaccine licensed for the control of footrot.
Michael Keaveney, who farms at nearby Athleague, visited Joseph Kennedy’s farm with veterinary practitioner Donal Flynn to hear Joseph’s story on the benefits of vaccination.
Michael farms in partnership with his father Liam in the village of Roundforth. They have a flock of just over 200 ewes. Ewe lambs are reared on the farm and those not needed for replacements are sold as ewe hoggets for breeding.
Persistent problem
In common with a large number of sheep farmers, the Keaveneys have a big problem with lameness.
“We footbath regularly and we treat all serious cases with an injectable antibiotic and an antibiotic spray. But the problem is still persisting.
“We still have up to 10% of our sheep lame at any one time. Lamb thrive is not what it should be and the time and labour involved in treating lame sheep is huge,” said Michael.
Joseph Kennedy outlined his footrot control strategy including vaccination when the ewes are housed. While he got a response in the first year after vaccination, he said he could definitely see a big response after the second year.
The body condition of the ewes and the excellent lamb performance on the Kennedy farm were aspects that particularly impressed Michael Keaveney.
Last year, Joseph Kennedy had twin lambs fit for sale at 12-13 weeks of age and the small number of singles were fit at 10 weeks, evidence of the excellent performance achieved.
Discussion
Michael is now having a discussion with Donal Flynn on the benefits of vaccination as part of the footrot control strategy.
According to Donal, vaccination as part of a rigid control strategy will be cost effective.
“As well as lifting productivity and greatly reducing labour, vaccination also helps to reduce antibiotic use, a very important consideration in the current climate of concern about over- use of antibiotics.”
Footrot and scald the major causes
According to Donal Flynn, footrot and scald account for 90% of lameness in sheep. CODD (Contagious Ovine Digital Dermatitis) accounts for 5% and the remaining 5% is the result of other causes, including strawberry foot, shelly hoof and abscesses.
“The first step in tackling lameness is to correctly identify the cause of the problem. Misdiagnosis and wrong treatment can often make the problem worse.
“It will pay to get your vet to carry out a detailed inspection, identify the bugs and prescribe the most effective treatment and control strategy,” he stressed.
He said footrot which is caused by two different bacteria is highly infectious. Housing, collection yards, gateways, wet areas and supplementary feeding areas are heavy sources of infection.
Every time a lame sheep takes a step a deposit of the bacteria is left behind and other sheep are at risk of infection. Sheep do not acquire immunity to infection.
Impact
“A productive sheep flock should have a scanning rate of 2.0, a weaning rate of 1.75, a target liveweight gain in lambs of 300g/day and ewe mortality of less than 2%.
“Lameness plays havoc with these key performance indicators. It depresses fertility, leads to higher incidence of twin lamb disease and results in ewes with poor colostrum and lower milk yield.
“The end result is lower lamb performance and the risk of increased ewe and lamb mortality not to mention the heavy financial and labour costs of treating infected sheep.”
Five Point Footrot Control Plan
Donal Flynn said that farmers who have adopted the following five point footrot control plan have achieved good success in greatly reducing lameness and improving overall sheep health and performance.
“But it requires a change of mindset on the part of farmers and a 100% commitment to all aspects of the plan if good success in controlling lameness is to be achieved.”
Treat – All clinical cases should be treated promptly and effectively, including the use of an injectable antibiotic as well as a localised antibiotic spray. Paring of hooves should be kept to the absolute minimum. It can delay recovery and can even make the problem worse.
Quarantine – All lame sheep should be isolated from the flock and treated accordingly. Keep bought-in sheep separate for at least 21 days.
Avoid Spread – Regular and proper footbathing helps to reduce the spread of the disease. Spreading lime at gateways and around feed troughs can also be helpful.
Cull – Some sheep are chronic carriers and will not respond to treatment. They are a continuing source of infection and should be culled. Donal recommends a two strike policy – if the sheep fails to respond to two treatments, cull it.
Vaccinate – Donal stated that where footrot is affecting 5% of the flock, vaccination of the entire flock, in conjunction with the other four measures, is highly cost effective.
“The best time to vaccinate is around a month before the start of the breeding season or before sheep are housed for the winter. Do not vaccinate within four weeks before and after lambing or within at least six weeks prior to shearing.”
“The primary vaccination course consists of two injections six weeks apart. In areas of constant disease challenge, re-vaccination should take place every six months.”
Most farmers expect sporadic abortions around the beginning of the lambing period. The level of sheep abortion can rise with increasing flock size. External non-infectious events can cause sheep abortion. However, a few isolated abortions can precipitate quickly into an outbreak or an ‘abortion storm’. When the incidence rapidly surpasses two per cent of the ewe flock effected or if there are several abortions in a short time period, then a diagnosis of the cause should be investigated. Many of the infectious agents that cause ewes to lose their unborn lambs can also affect women. Therefore, it is important to obtain an accurate diagnosis of the cause to protect against these devastating diseases.
Diagnosing the cause
Freshly aborted lambs and the placenta (cleanings), if available, should be submitted to the regional veterinary laboratory for post mortem analysis. Some pathogens damage the placenta therefore they remain a valuable part of the diagnostic process.
Major pathogens associated with sheep abortions
In 2016 there were 728 cases of sheep abortion investigated by regional veterinary laboratories on the island of Ireland. As in previous years, toxoplasmosis and enzootic abortion of ewes (EAE) were the two most commonly recorded causes of ovine abortion.
Table one: Summary of the causes of ovine abortion diagnosed by AFBI and DAFM in 2016. Reference: All-Island animal disease surveillance report, 2016.
Enzootic abortion
Enzootic abortion is caused by a bacterial agent called Chlamydophila abortus and represents an important production disease of sheep flocks in many countries.
The infection is introduced to a clean flock via purchasing infected replacement ewes. Healthy ewes become infected with C. abortus through contact with the bacteria in lambing fluids and the placenta of an aborting ewe, or through breathing in aerosols from the contaminated environment.
Infection up to 5-6 weeks prior to parturition results in clinical disease and abortion in the final 2–3 weeks of gestation occurs, or birth of stillborn or weak lambs that frequently die in the first few days of life.
Ewes that do not abort can become latent carriers with no clinical signs until the next lambing season. Surviving lambs born to infected mothers may be affected in their first pregnancy.
Control measures in sheep
Management of Enzootic Abortion should always include the rapid removal of ewes that are aborting. In addition, aborted foetuses and cleanings from the lambing pen, followed by thorough disinfection. Antimicrobial treatment of ewes with long-acting antibiotics in the face of an outbreak is commonly practiced. However, the benefit of this treatment is difficult to evaluate as they provide no protective immunity in subsequent lambing seasons.
Vaccination is useful to reduce the risk of Enzootic Abortion in uninfected ewes and reduce the spread of the disease within the flock. All breeding females should be vaccinated before tupping. Initially the whole flock should receive a vaccination dose before introduction of the ram and replacements are vaccinated every year.
Human health considerations
It is important to remember that Enzootic Abortion is a zoonosis which can have particularly serious consequences for pregnant women. Infection with C. abortus is usually due to exposure to infected foetal fluids and membranes of sheep or goats. Women who are, or may be, pregnant are advised to avoid involvement with the flocks of small ruminants at lambing time.
For more information, speak to your veterinary surgeon.
