Sheep lameness – Underlying issue to reduced performance?

Lameness in sheep

Lameness in sheep is a significant issue in flocks in Ireland. Lame sheep are a cost to any farm business due to the costs associated with treatment, control and loss of productivity.

When compared to a normal ewe, lame ewes can have:

  • 15% lower conception rate;
  • 20% decrease in body condition score;
  • 20% lower lambing percentage;
  • Lower ewe survival;
  • Poor lamb survival;
  • Reduced growth rate in lambs born to lame ewes;
  • Fewer lambs sold finished.

For effective treatment it is important that a correct diagnosis is made to identify the cause of lameness affecting each ewe. The three most common causes of lameness in sheep are bacterial infections of the skin and hoof, including: Scald, Footrot and Contagious Ovine Digital Dermatitis (CODD).

Misdiagnosis leads to mistreatment

Causes and symptoms of lameness in sheep

Bacteria that affect the skin and hoof are normally found in the digestive tract of animals. Virulent strains of Dichelobacter nodosus, the primary cause of Footrot in sheep, are maintained in the flock by both lame and recovered carrier sheep.

90% of lameness is caused by Scald and Footrot.


Scald is the term given to inflamed or reddened skin between the digits. The horn is usually unaffected. A damp environment predisposes sheep to developing scald.

Wet grass or moisture between the toes leads to an impairment of the defence properties of the skin which normally acts as a barrier to infection.

Bacteria which can be found on the surface of normal feet, Fusobacterium necrophorum, invade the skin when wet, resulting in damage. The interdigital skin can appear red and swollen or grey.

Lameness is usually mild and resolves when underfoot conditions improve. In the meantime, however, the damaged skin can allow entry of other potentially harmful bacteria such as the agent causing Footrot, Dichelobacter nodosus.


Check out our NEW farmer brochure for all you need to know about Footrot in sheep! Click the arrows below to scroll through the pdf document.

Causes of Footrot in sheep

There are two forms of Footrot in sheep, benign and virulent. Benign Footrot is caused by certain strains of Dichelobacter nodosus that are less damaging than the strains that cause virulent Footrot.

The initial damage done to the skin is by Fusobacterium necrophorum resulting in Scald can allow the entry of bacteria that cause Footrot. This leads to further damage of the soft tissue underlying the hoof resulting in Footrot. Often more than one foot can be affected.

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Virulent Footrot results in severe horn separation and the formation of a foul-smelling discharge.

Dichelobacter nodosus bacteria survives in the feet of lame sheep or recovered carrier animals. They can live in wet, muddy environments for approximately four days. During the grazing season, survival is enhanced by wet lush pastures. At housing, damp underfoot conditions improve transmission from either lame or recovered carrier animals to sound ewes.

Contagious Ovine Digital Dermatitis (CODD)

The exact cause of contagious ovine digital dermatitis is yet to be defined. However, Treponema sp. bacteria are frequently detected along with other microbes in cases of scald and footrot in sheep.

Ulcers are found at the coronary band, at the skin hoof boundary. Ulcers can also be found on the hoof wall. The condition differs from footrot in that there is a sudden onset of more severe lameness.

The majority of affected sheep become severely lame. In a clean flock, free of the bacteria causing CODD, purchasing infected sheep is the main route of entry.

The Five Point Plan Approach

The 5 Point Plan was developed using existing published science on sheep lameness, and practical experience from farmers who had achieved sustained low levels of lameness.

The 5 Point Plan has five action points that support the treatment of the animal in three different ways: Building resilience; reducing disease challenge; and establishing immunity.

Reducing the prevalence of lameness requires a long-term commitment to implementing all five points of the plan.

Talk to your vet for more information on creating an action plan for your flock!

Footrot vaccination a big success on Roscommon sheep farm

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.


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.


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.


“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.”

  1. 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.
  2. Quarantine – All lame sheep should be isolated from the flock and treated accordingly. Keep bought-in sheep separate for at least 21 days.
  3. 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.
  4. 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.
  5. 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.”

Salmonella – The notorious bacterial disease that no-one wants on their farm


Salmonella infection is one of the most well-known diseases affecting cattle in Ireland. Samonella infections is a serious drain on the profitability and productivity of the Irish dairy herd. In addition, there is the added risk of being a zoonotic disease, meaning infection can be transmitted to humans from animals. Infection in the dairy herd has the potential to cost up to €112 per cow, per year. Research has shown that herds which include vaccination as part of a control plan record superior profits in comparison to unvaccinated, positive herds to a value of €11,800 based on a 100-cow herd.

Salmonella is considered endemic in Ireland and can be commonly found in herds throughout the country. The majority of salmonella infections in Irish cattle are caused by one of the following serotypes: Salmonella typhimurium or Salmonella dublin, with abortion outbreaks typically associated with Salmonella dublin. Other clinical signs such as pneumonia, meningitis, arthritis, osteomyelitis and sloughing of extremities are also seen. Salmonella is primarily shed in the dung of infected cattle and infection is usually picked up by oral ingestion. Once an animal is infected, they can become carriers of the infection for life. This is known as latency and it is an important component in maintaining infection within a herd. Carrier cattle will often shed the bacteria during times of stress such as around calving or changes in management, acting as a source of infection to the rest of the herd. As many dairy herds have expanded in recent years, there has been a heightened risk of introduction of the disease through the buying-in of these carrier animals.


              As with any disease outbreak it is important to involve your attending veterinary practitioner to assist with diagnosing the exact cause of disease and to formulate an effective control plan. Diagnosis of infection by post mortem investigation is considered gold standard. Any aborted foetuses should go to the local regional veterinary laboratory as soon as possible. In a scour outbreak, multiple dung samples can be used to help identify bacteria while paired blood samples can be taken can be taken to demonstrate a rising level of immunity to the infection. The first sample is taken during the active phase of infection while the second sample is taken four weeks later.

Bulk milk antibody testing can be a useful surveillance tool for dairy herds too. Although results might not indicate active infection within herd at the time of sampling, monitoring results can give an idea of the level of exposure within the herd and potential trends of infection. Recent research has shown exposure of Irish dairy herds to salmonella is very common, with 49% of bulk milk tanks testing positive for salmonella antibodies, indicating cattle in these herds had come into contact with the bacteria at some point in the preceding months.


As the disease is notoriously difficult to eliminate from farms, vaccination and strict management measures must be implemented to reduce the spread of infection. These can include –

  • Maintaining a closed herd/purchase from herds of known disease status – If buying in, quarantine arrivals for a period of 4 weeks minimum.
  • Strict biosecurity – Cows which have aborted should be isolated for one month and any abortion materials should be disposed of in a hygienic manner. Ensure fencing is stock proof to avoid break-in infection from neighbouring herds.  
  • Management of slurry – Salmonella bacteria can survive for prolonged periods in slurry tanks and for up to 300 days on soil. Faecal material from clinical cases must be prevented from entering the slurry tank.
  • Strict hygiene – A disinfection point should be in place for everyone who enters and leaves farm to use. Hygiene of buildings between batches of animals is critical while personal hygiene should also be maintained as a result of the zoonotic risk.
  • Rodent and bird control – As pests can spread disease, a plan should be in place for rigorous control, especially with regard to access to feed stores.


            Bovivac S is the only vaccine available for Salmonella dublin and Salmonella typhimurium in Ireland. For best herd control of salmonellosis, it is advisable to vaccinate all animals in the herd. Healthy calves from approximately three weeks of age can receive the primary vaccination course of two 2ml injections separated by an interval of 14-21 days.  Calves over six months of age and adult cattle should receive two 5ml injections 21 days apart. Depending on the level of infection circulating in the herd, one annual vaccination should maintain a sufficient level of immunity in the herd. Although not licensed for the control of abortion, research has reported that the proportion of Salmonella dublin positive abortions from vaccinated herds was significantly lower than in herds which were not vaccinating. To determine the most appropriate time to vaccinate your herd, please consult with your attending veterinary practitioner.

In conclusion, the implications of a salmonella outbreak can be severe and result in significant financial, production and welfare costs. Not to mention the stress of its potential zoonotic risk. Vaccination can form the cornerstone of control along with good management, strict hygiene protocols and high biosecurity standards.

Tackling lungworm on a Cork dairy farm

This post is provided by Tommy Heffernan

Three years ago I met a very enthusiastic young vet student and his mam for the first time. Sean has since qualified and is now working as a full-time vet in Glenbower vets in Cork, a member of XLVets Ireland. I visited Sean on his family dairy farm to see how he has tackled lungworm control since 2013. His dad Gerry milks 110 Holstein Friesians with a split herd, with 45 calving down in autumn and the rest in spring, all calves being taken through to beef.

Lungworm and coughing dairy cows are now a big problem in many herds. Over the last five years, we have seen more and more herd cases where this problem is dramatically effecting performance and profit.

Over the coming weeks, I’m going to take a deeper look at all things lungworm, in an awareness campaign.

The problem

Lungworm is an increasing issue on many Irish pasture-based systems. The weather, overuse of dosing (youngstock) and grazing strategies all mean the lungworm parasite (dictyocaulus viviparous) has been affecting many herds.

Traditionally we have controlled this parasite with the use of anthelmintics or wormers. On some dairy farms, this has been limited during lactation by the fact only one product is now licensed. I’ve had many conversations with farmers now dosing cows 3+ times during the grazing season.

Lungworm control is also difficult because of the sudden onset of symptoms and sometimes difficulty in diagnosing reinfection syndrome. Where often as Sean described himself in the video, where vets use BAL (bronchoalveolar lavage) or lung washes to make a diagnosis.

With only one licensed product for lactating animals and the ever-growing threat around anthelmintic resistance, this means we must look at options around control on farms dosing cows regularly during their lactation to control lungworm.  With the development of immunity being key to lungworm control, the use of the lungworm vaccine is a real option for farmers.

Sean’s story

In 2012 Sean had big issues with coughing cows and lungworm. This was a very wet year, and these are conditions that lungworms really thrive in.

The cows and young heifers were coughing while at grass, and dropping back in production. They were dosed but the problem continued when the dose ran the course of its therapeutic dose. This meant a summer where cattle on the farm had to receive several doses (anthelmintics).

They investigated the problem with their vet and diagnosed lungworm.

Sean began researching his options and discovered a lot of farms in the UK using the lungworm vaccine with good success. While whole herd vaccination is very much the gold standard, Sean implemented a partial dosing strategy before his 2013 grazing season.

He targeted all his 2nd grazers and 1st lactation animals with two doses of oral lungworm vaccine during the winter housing period of 2013. He now continues this protocol with all yearlings receiving two doses and 1st lactation (heifers) getting an annual booster.

He got great results with the lungworm vaccine since implementing the program. Over the last seven years, he hasn’t had to dose his herd during the grazing period. He continues to monitor his younger stock for other worms and dose them accordingly (calves 1st grazers). Cows now only receive a worm dose at the end of their lactation at housing

The key thing around lungworm vaccination seems to be planning. It is a live vaccine and needs to be ordered in advance of the dosing period. It also must be stored and used quickly by oral administration.

While Sean has had fantastic results every farm must assess their own risk and come up with a plan or strategy with their vet. The aim for any farm should be to reduce down anthelmintics where possible especially in adult animals in the herd.

Can cats cause abortion in my ewes?

There are many infectious and non-infectious causes of abortion in ewes. However, one of the most commonly diagnosed agents can be introduced by our own farm cats.

Cats become infected with Toxoplasma gondii when they eat infected prey. The parasite multiplies in the lining of the guts before passing out in their faeces.

The main source of infection for sheep is feed and pasture contaminated with cat faeces containing infectious oocysts or parasite eggs.

Ref: Toxoplasmosis Fact Sheet, Moredun Research Institute

Should I rehome my farm cat?

Cats shed oocysts for around 10-14 days so by the time ewes are infected and abortions occur, your cat has developed strong immunity and has stopped shedding. Most cats will only start shedding oocysts again if they become ill or are infected with an immunosuppressive virus.

What is the outcome of infection?

After infection, Toxoplasma gondii parasites circulate in the blood of a pregnant ewe and can cross the placenta, spreading to the unborn lambs.

Depending on the timing of infection and the stage of gestation, the clinical outcome may differ.

If infection occurs for the first-time in mid pregnancy, Toxoplasmosis has a profound effect on the reproductive health of the ewe. Clinical signs include abortion or stillborn and/or weak lambs often along with a small, mummified foetus.

Characteristic ’white spot’ lesions on the placenta may be present which are usually visible to the naked eye.

Infection occurring during either early or late gestation can result in foetal death and loss or abortion. However, infection in the latter part of gestation, when foetal immunity is relatively well-developed, may have no clinical effect, with the lambs being born normal, but infected and immune.

Following infection, sheep acquire an immunity. They remain immune but infected for life (with Toxoplasma gondii in tissue cysts in brain and muscle) and will not usually abort due to toxoplasmosis in future pregnancies.

Human health considerations

Toxoplasmosis is an important zoonosis. Humans become infected by ingesting tissue cysts in undercooked meat, or consuming food or drink contaminated with Toxoplasma gondii oocysts.

If contact with animals that have aborted or have recently given birth is unavoidable, open wounds (cuts, grazes etc,) should be covered with waterproof dressings and hands should be thoroughly washed after handling animals to prevent the possibility of infection. Pregnant women should avoid all contact with ewes at lambing time or rearing orphan lambs that could be infected.

Most infections in humans are asymptomatic, but the parasite can produce devastating disease depending on the time infection occurs. Congenital infection occurs only when a woman becomes infected during pregnancy, and infections acquired during the first trimester are more severe than those in the second and third trimester. A wide spectrum of clinical disease occurs in congenitally infected children.

Control measures in sheep

Control measures include good management of food and water sources to limit the contamination with cat faeces, as well as vaccination of breeding females prior to tupping. Initially the whole flock should receive a vaccination dose at least three weeks before introduction of the ram. Replacements are vaccinated each year thereafter, again at least three weeks before tupping. Speak to your veterinary practitioner for more information.

MSD Animal Health Completes Acquisition of VECOXAN®

MSD Animal Health Completes Acquisition of Worldwide Rights to VECOXAN® Brand of Parasiticides for Ruminant Portfolio  

Broadens MSD Animal Health’s Position with Enhanced Parasite Protection in Calves and Lambs

MSD Animal Health, a division of Merck & Co., Inc., Kenilworth, N.J., USA, today (Aug., 3, 2020) announced the completion of its previously announced acquisition of the worldwide rights to VECOXAN® (diclazuril), an oral suspension for the prevention and treatment of coccidiosis in calves and lambs, from Elanco Animal Health.

VECOXAN is efficacious, in lambs, against coccidiosis caused by Eimeria crandallis and Eimeria ovinoidalis, and in calves, against coccidiosis caused by Eimeria bovis and Eimeria zuernii. VECOXAN is available in Europe, South Africa, South Korea and Japan.

Parasite control and protection is an essential and significant part of ruminant overall health management and outcomes. “With advanced digital and diagnostic solutions to manage the welfare of animals as critical components of our technology, we are dedicated to advancing the health and well-being of animals and the people who take care of them,” said Rick DeLuca, president, MSD Animal Health.  “This complementary product for youngstock will add to our existing portfolio of veterinary medicines, vaccines and services, and underscores our commitment to The Science of Healthier Animals®. The extensive breadth and depth of our product portfolio provides a full range of complementary solutions for our customers to improve the health and well-being of animals and the people who care for them.”

“The first months of a calf’s or lamb’s life can impact its future health. VECOXAN will expand our portfolio for the prevention of disease for younger animals, including the the recently launched Bovilis® INtranasal RSP™ Live, an intranasal vaccine to help protect young cattle against respiratory disease,” said Philippe Houffschmitt, DVM, Global Ruminants Lead, MSD Animal Health. “As global demand for protein increases, we are committed to providing comprehensive solutions that will support a safe and sustainable food supply.”

Coccidiosis, a common cause of scours (diarrhoea) in lambs and calves that is highly prevalent on cattle and sheep farms, is caused by protozoan parasites called Eimeria that multiply in the intestinal wall, transmitted from animal to animal by the fecal-oral route. Clinical signs include painful scours with or without blood, and decreased appetite and depression, which may progress to dehydration and weight loss. Coccidiosis primarily affects young animals; calves and lambs as young as three to four weeks of age may be affected.

Coccidiosis causes significant economic loss to farmers and producers due to reduced feed conversion, reduced growth rates, reduced performance or death, and by increased susceptibility to other infections, such as intestinal disease or Bovine Respiratory Disease.


            VECOXAN is an anticoccidial of the benzeneacetonitrile group without antimicrobial activity and has anticoccidial activity against Eimeria species. The product can be used in calves and lambs, beef and dairy, of any weight, in any management system, without environmental restrictions. It has a zero-day meat withdrawal period.

About MSD Animal Health

For more than a century, MSD, a leading global biopharmaceutical company, has been inventing for life, bringing forward medicines and vaccines for many of the world’s most challenging diseases. MSD Animal Health, a division of Merck & Co., Inc., Kenilworth, N.J., USA, is the global animal health business unit of MSD. Through its commitment to the Science of Healthier Animals®, MSD Animal Health offers veterinarians, farmers, pet owners and governments one of the widest ranges of veterinary pharmaceuticals, vaccines and health management solutions and services as well as an extensive suite of digitally connected identification, traceability and monitoring products. MSD Animal Health is dedicated to preserving and improving the health, welfare and performance of animals and the people who care for them. It invests extensively in dynamic and comprehensive R&D resources and a modern, global supply chain. MSD Animal Health is present in more than 50 countries, while its products are available in some 150 markets. For more information, visit, or connect with us on Twitter @msd_ah.


  1. EU Summary of Product Characteristics. Vecoxan 2.5 mg/ml Oral Suspension for lambs and calves. Available at
  2. Agneessens J, Goossens L, Veys P, Gradwell D (2005). Efficacy of diclazuril (Vecoxan) against naturally acquired Eimeria infections in suckling beef calves and economic benefits of treatment. Cattle Practice, The Journal of the British Cattle Veterinary Association, 13, 231-234.
  3. Agneessens J, Goossens L, Louineau J, Daugschies A, Veys P. (2006) Build-up of immunity after a diclazuril (Vecoxan) treatment in calves. Poster at 24th World Buiatrics Congress, Nice, France.
  4. Willemsen MHA, Zechner G, Goossens  L, Jacobs J, (2011). Coccidiosis under German field conditions: the importance of immunity. Poster at European Conference of Bovine Health Management, Beerse, Belgium.

Reducing the risk of Enzootic Abortion

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. 

Sheep abortion article

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.

Sheep Production

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.

‘Vaccinating my sheep against abortion gives me great peace of mind’

Bought-in ewe hoggets resulted in a serious abortion outbreak for Galway sheep farmer Bernie Geraghty.

“Around seven years ago, I bought 28 hoggets and a third of them aborted. Ever since then, I have been vaccinating against both enzootic abortion of ewes and toxoplasmosis.”

“I vaccinated the entire flock the first year.  I now only need to vaccinate the replacement ewe lambs.”  

“Even though I now breed my own replacements, I feel vaccination against abortion is a worthwhile and cost-effective method of control. It gives great peace of mind,” said Bernie who runs a flock of 140 ewes and 25 replacement ewe lambs at Doon, Kilconnell.

He is participating in an information and awareness campaign run by XLVets on the risks and costs of abortion and the role that vaccination plays in a strategic control plan.  The campaign is run in association with MSD Animal Health which manufactures vaccines for the control of both toxoplasmosis and enzootic abortion.


As part of the campaign Bernie Geraghty was joined on his farm by John Jenkins from the nearby parish of Ballymacward.

John, who combines farming with an off-farm job, runs a flock of 70 ewes.  He has not been vaccinating against abortion up to now but is now seriously considering the introduction of vaccination as part of his sheep health programme.

Their discussion was videoed and is being disseminated through a range of platforms to the wider farming public.

Veterinary Advice

Bernie Geraghty is in the happy position of having his son Conor as his veterinary practitioner and he also participated in the videoed discussion.

Based in Mountbellew, Conor and practitioner Gerry Neary run Geraghty and Neary Veterinary, based in Mountbellew.  The practice services some 1,400 farmers in east Galway and south Roscommon. 

Conor is also current President of Veterinary Ireland and is a director of XLVets Ireland, a network of over 30 independently owned veterinary practices nationwide that share knowledge and experiences in order to improve the quality of service to farmers.

He believes that discussion among farmers is the key to the adoption of new and better practices and this is the driver behind the current XLVets campaign on the role of vaccination in reducing abortion outbreaks.  

Vital to establish the causes of sheep aborting

“Always investigate the reasons for abortions.  Arrange with your vet for swabs to be sent to FarmLab Diagnostics in Elphin and for foetuses and placentae to be sent to the regional veterinary laboratory,” urged Conor Geraghty.

Analysis by regional veterinary laboratories shows toxoplasmosis and enzootic abortion to be the leading causes of abortion in sheep.

He said outbreaks of toxoplasmosis and enzootic abortion are regular occurrences on client farms every year.   He recalled an outbreak on one client’s farm two years ago where 50% of the flock aborted.

Mental Impact

“As well as the huge financial costs involved, an abortion outbreak has a severe mental impact on farmers and their families.”

He said that while toxoplasmosis is not passed from ewe to ewe, enzootic abortion is highly infectious with organisms passed from ewe to ewe in infected afterbirth, on new lambs and in vaginal discharges for up to three weeks after lambing.

“Where enzootic abortion is diagnosed, it is vital to isolate aborted ewes.  If fostering, only foster male lambs.

“Where an outbreak occurs, the use of an antibiotic injection may reduce the number of enzootic abortions.  But this should only be done in consultation with the vet.” 


He said vaccination as part of a flock health plan plays an important role in protecting against toxoplasmosis and enzootic abortion.  It also reduces the use of antibiotics, a hugely important issue in the current climate of concern about over-use of antibiotics.   

“The one shot vaccines for toxoplasmosis and enzootic abortion can be given to breeding ewes and lambs (from five months of age) during the non-pregnancy season.  Vaccination must be completed at least four weeks before sheep go to the ram.

“The two vaccines can be administered at the same time, but not mixed, and must be given in separate injection sites.  Generally, just one shot of each vaccine is required during the lifetime of the ewe.”

What you need to know about toxoplasmosis and enzootic abortion

Toxoplasmosis, caused by a microscopic parasite Toxoplasma gondii (T. gondii), is most commonly caused by contaminated cat faeces in feed, bedding or manure or directly on to pasture.

A single cat dropping can contain enough eggs to infect more than 100 ewes and almost 75% of ewes are believed to come in contact with T. gondii during their lifetime.

Symptoms can include barren sheep, abortions, stillbirths, weakly lambs and mummified foetuses. 

Vaccination is the only way to effectively build uniform immunity to toxoplasmosis in the flock.  As older ewes are more likely than younger ewes to have already been in contact with T. gondii, it may be an option to vaccinate the younger sheep and then vaccinate all replacements as they enter the flock.

Where the risk of infection is high on a heavily contaminated farm populated with previously unexposed sheep, initial whole flock vaccination is cost effective. 

Enzootic abortion

An outbreak of enzootic abortion, caused by a bacteria-type organism called Chlamydophila abortus, can result in 30% of sheep aborting.  The disease is usually caused by infected bought-in replacements but it can also be spread by wildlife carrying infected placentae from farm to farm.

When a ewe aborts she sheds large numbers of organisms, which can infect any in-contact ewe or lamb.  These newly infected sheep will not show any signs of infection. 

The organisms remain dormant in the body until the ewe lambs again.  In infected lambs, they can remain dormant for up to two years.   About three weeks before lambing, the placenta becomes inflamed and abortion occurs.

While ewes that aborted often continue to have a normal lambing in subsequent years, they are carriers of the disease and may still shed organisms resulting in infection of other sheep and lambs.  

Vaccination will effectively reduce the risk of enzootic abortion as part of a flock health plan.  Because there is no test to identify latently infected sheep, it is important to vaccinate all breeding sheep in the first year.  After that, only replacements need to be vaccinated.

WEBINAR: Method of measuring greenhouse gases in agriculture is flawed, says leading scientist

The case for treating methane from agriculture differently to long-lived gases, such as carbon dioxide, in the debate on global warming is undeniable. This is according to leading global air quality scientist Professor Frank Mitloehner who spoke during a recent webinar host by MSD Animal Health.

During the webinar, Prof Mitloehner highlighted what he described as the flawed system of measuring the contribution of livestock production to greenhouse gas (GHG) emissions.

“Methane is a powerful GHG, with about 28 times the warming potential of carbon dioxide over 100 years.  But methane does not hang around for 100 years.

“Methane only lasts in the atmosphere for 10 years.  In contrast, carbon dioxide persists for up to 1,000 years,” said Prof Mitloehner.

He said stock gases, such as carbon dioxide, accumulate over time as they stay in the atmosphere.  Flow gases, such as methane, stay stagnant as they are destroyed at the same rate of emission.


“It’s a cyclical process, referred to as the biogenic carbon cycle, and it’s been around as long as life itself.

“Therefore, if herd sizes do not increase for 10 years, additional methane is not added to the atmosphere.  This is why the case for treating methane differently to long-lived gases is indisputable.”

He said the role of grassland in acting as a carbon sink must be given more prominence in the climate change debate.

“Grassland may well be a more reliable carbon sink than forestry as most of its carbon is stored below the ground whereas forests store carbon above the ground.”

Fergal Morris, general manager of MSD Animal Health who moderated the webinar highlighted the big variation between countries and regions in the level of carbon sequestrated by grassland.  For example, there is 20 times more carbon per gram in Irish soil than in Spain.

Prof Mitloehner said all this does not mean that methane emissions are important.  The effort to reduce emissions must be accelerated through a greater concentration on smart farming.

He referred to the reduction of 2.2m tonnes, or 25%, in methane emissions by the Californian dairy industry during the past four years.  This was the result of a collaborative effort by state authorities, farmers and scientists.  Initiatives undertaken included the installation of biogas plants.  

“Scientists and farmers are also working on feed additives and other projects to help them reach their goal of a 40% reduction of methane by 2030.”

Animal Health

Galway-based veterinary practitioner and President of Veterinary Ireland Conor Geraghty also participated in the webinar and highlighted the importance of animal health in reducing methane emissions.

He said diseases and poor fertility greatly increase the level of emissions.  Preventing the major disease threats through nutrition, biosecurity and strategic vaccination will reduce emissions and increase profits.

According to Fergal Morris, diseases such as salmonella and BVD in dairy cows increase emissions by up to 20%.  Infertility can result in a 15% increase in emissions while fluke can lift emissions by more than 10%.

IRP technology reduces the bacteria's ability to absorb iron
nly one cattle pneumonia vaccine registered in Ireland utilizes IRP technology.
Bad Science

Leading European food scientist Professor Frederic Leroy told the MSD webinar that ‘bad science and extreme agendas’ are misleading consumers on the health risks associated with meat consumption.

“The health dangers of red meat are far from being supported by robust scientific evidence Calls for the planet to go vegan are pure nonsense and are ideologically driven by people who have a philosophical perspective and a bias against certain types of healthy foods,” said Mr Leroy, who is professor of food science and biotechnology at Vrije University in Brussels.

“Diets based solely on plant-based foods are restrictive, less robust, and may result in a greater number of deficiencies in essential nutrients, especially in vulnerable groups.”

He highlighted the health risks for children raised on vegan or vegetarian diets, stressing that red meat has an important place in a healthy, sustainable diet.

In relation to GHG emissions, he said the real protein value and nutrient density of different foods should be looked at.

“Many foods with low GHG equivalent values have low nutritional values relative to the higher nutritional density of meat-based products.

 “We therefore need to examine if the higher greenhouse gas equivalent values of meat-based foods can be offset by their higher nutritional values.”

Presentation Links

Fergal Morris (General Manager, MSD Animal Health Ireland):

Professor Frank Mitloehner (UC Davis Professor & CE Air Quality Specialist, Dept Animal Science):

Professor Frédéric Leroy (Vrije Universiteit Brussel, Bioengineering Science Department):

WEBINAR INVITE: Greenhouse Gas Emission; Are Irish cattle the solution or the problem?

MSD Animal Health are extremely lucky to have secured two world renowned speakers; Professor Frank Mitloehner (Professor and Air Quality Extension Specialist, UC Davis) and Professor Frédéric Leroy (Professor of Food Science and Biotechnology, Vrije Universiteit Brussel), for a webinar on June 2nd 7.30-9.30pm.

Professor Mitloehner will discuss the role of cattle in climate change in the first presentation. Thereafter, Professor Leroy will discuss meat, health and dietary guidelines. Conor Geraghty (President of Veterinary Ireland) and Justin McCarthy (Editor, Irish Farmer’s Journal) will join for a panel discussion at the end of both presentations. MSD Animal Health General Manager, Fergal Morris, will also provide a short presentation and moderate the session.

This is a great opportunity to hear the facts when it comes to the carbon footprint of Irish agriculture. There will also be a focus on the role of the veterinarian, farmer and wider agricultural industry in this equation.

We would like to invite you to the meeting and you may register via the link below. We look forward to welcoming you to the event.

Meeting registration: