Abortion in cattle and sheep is common, acceptable levels of 2% are considered ‘normal’ but we see outbreaks where losses can be more than 20%.

Obviously, the economic cost of abortions can be extremely high, not just the cost of the dead calves and lambs but the production loss of the dam; animals that have aborted end up being culled early and need to be replaced.

There are many different causes of abortion, both environmental and contagious. Reaching a diagnosis is fundamental to the advice we give and the plan going forward.

The UK is officially free of Brucellosis, but we still carry out routine surveillance. Bulk milk is tested routinely for Brucellosis, but beef cattle abortions should be reported and tested by your local vet if authorised by local APHA.

If abortion levels rise above a 2% level, we strongly recommend further investigation. To have the best chance of reaching a diagnosis, we require as much material as possible. This would include the foetuses, placenta and possibly blood samples from the dam. Taking material directly to a local SRUC post-mortem facility is ideal but your local vet can also take samples on farm and post them for testing. The SRUC will provide abortion sampling kits and advice to your local practice.

It can be frustrating when we have gone to the effort of taking samples but didn’t get a diagnosis. In these situations, we can take comfort that many causes will have been ruled out but we suggest further sampling if losses continue.


The four most common causes of cattle abortion found by SRUC since 2017 are environmental and not spread from cow to cow.

A bacteria called bacillus was the most common cause. The source of this bacteria is contaminated water troughs and feeding. We always look at reducing the source of potential infection, keep water troughs clean and don’t feed contaminated forage to pregnant cows. Listeria, fungi and T.pyogenes are the next most common causes of abortion in cattle.

Contagious abortions are less common, but it is always very important to rule these out. Salmonella species are the most common. Salmonella may affect animals of different ages including calves, animals may be sick, scour and have high temperatures but it is worth investigating further.

Sources of new Salmonella infection may be bought in cattle, wildlife vectors including birds and vermin. Contaminated bulk feeds have also been linked to new Salmonella infections. The source of new infections may never be found but important to be aware of the risks.

Getting a definitive salmonella diagnosis is essential as we have a licensed vaccine for S.dublin and S.typhimurium. Early vaccination of at risk stock can prevent further losses.

Neospora is another infectious cause of abortion spread by dogs and foxes but also spread from an infected cow to her heifer calf. Blood sampling dams and analysis of aborted foetuses can let us know if this is significant and requires further testing and management. It is possible to manage neospora at a herd level by blood sampling, culling positive animals and not breeding from the heifers of positive cows.

BVD, IBR and Leptospirosis can also cause abortions in cattle as well as other symptoms. These are easy to identify from bulk milk or blood tests and there are highly effective vaccines to control these diseases at a herd level.


Abortion outbreaks in sheep can be severe and early diagnosis is essential to manage the problem. Disappointingly, sheep abortion investigations dropped last year at the SRUC but it is essential the lab receives abortion material to get a diagnosis.

By far the two most causes of abortion in sheep are still Enzootic abortion (EAE) and Toxoplasmosis.

Enzootic abortion is highly contagious and spread by ewes that have previously been infected. Newly infected ewes tend to carry the infection and abort the subsequent year. If left undiagnosed, newly infected flocks can experience minimal losses in the first year but much higher losses in subsequent years as infection spreads.

New infections occur due to the purchase of infected female sheep, including hoggs and gimmers. It is possible to source EAE accredited free ewes but biosecurity is essential to maintain freedom from this disease. Unfortunately, there are fewer accredited sheep available. Highly affective vaccines are available for the control of EAE, vaccines are cost effective and can give lifelong protection.

Toxoplasmosis is a protozoa parasite which infects cats and mice. Infected cats spread toxo in their faeces. Pregnant ewes exposed to contaminated pasture or feed will abort in the same season. Losses can be significant if ewes are exposed to a high challenge. Again, there is a highly effective vaccine to protect against toxo. Vaccinating non-pregnant ewe gives near lifelong protection. Vaccine shelf-life is short and availability has been an issue so early planning is vitally important. Prescription only medicated feeds are available to reduce losses due to toxo in unvaccinated flock situations.

Campylobacter and Salmonella are other contagious causes of abortion in sheep. Highly infectious and spread by carrier ewes, infection will spread in the same season and cause abortions. The ewes are more likely to be sick in themselves.

If abortions are more than 2%, further investigations are really important. Isolate aborted animals and dispose of potentially infectious material and bedding until a diagnosis has been reached.

Getting a definitive diagnosis is key to our advice to prevent further losses. EAE, Campylobacter causes may require whole flock antibiotic treatment. Salmonella may require vaccination of at risk animals, EAE and Toxo, require vaccination of non-pregnant ewes.

Work closely with your local vet, discuss the risks in your herd/flock health plan and be proactive with investigations and testing. Don’t be frustrated if results come back negative, we’ll have ruled out lots of significant causes. If losses continue, keep testing. Given the economic impact of abortion outbreaks, it is easy to justify investigations, whole group treatments and vaccination programmes.