Swine dysentery
A bacterial disease causing diarrhoea and weight loss that severely limits productivity – and a serious threat to herds selling breeding pigs.
Seeing unexplained diarrhoea and wasting?
Contact your vet immediately, especially if there is blood or mucus in the diarrhoea. Swine dysentery is not a notifiable disease, but please let the Scottish Pig Disease Control Centre know on 01466 792284 or vet@scottishpigs.org.uk, so that neighbouring units, hauliers and other contacts can be protected.
The disease and its cause
- Swine dysentery is a bacterial disease of pigs caused by Brachyspira hyodysenteriae.
- It causes diarrhoea and weight loss. Affected pigs take longer to reach slaughter weight, and the farm’s productivity and viability suffer.
- It is a particular threat to farms selling breeding pigs: if they become infected, their UK and international trade is devastated.
- Resistance to the limited range of treatments can develop. Occasionally the organism is resistant to all available treatments.
- There is no vaccine.
Signs to look for
Disease is usually most obvious in growers, finishers and younger breeding stock, with low to moderate death rates. Look for:
- diarrhoea, often grey-brown and watery at first, sometimes containing mucus and blood
- loss of appetite
- wasting and poor growth
Blood and mucus are not always seen. How severe the disease is depends on the age of the pigs, their immunity, diet, other diseases present and the strain of the bacterium.
How it spreads
Infected pigs, their faeces and manure, and anything contaminated with manure can spread infection between farms:
Carrier pigsPigs can carry and shed the bacteria without obvious signs
LorriesEspecially from abattoirs, where cross-contamination can happen
Slurry & equipmentSlurry tankers, machinery and shared equipment
Boots & peopleContaminated boots and clothing
RodentsMice and rats can carry the infection on a unit
BirdsBirds can also carry itAn infected farm is a risk to others both nearby and further afield.
Diagnosis
Your vet will send faeces or pigs for laboratory testing. Both Brachyspira culture and PCR are recommended. Prompt diagnosis means control measures can start quickly, which helps limit spread.
Testing also picks up other Brachyspira species. New species causing diarrhoea have been found in Europe, and one, B. hampsonii, has been detected in GB pigs, which is another reason to get the cause of a diarrhoea outbreak diagnosed.
Keeping it out
- Audit your biosecurity regularly with your vet, and fix weak points. See our Biosecurity page.
- Buy pigs only from herds free of swine dysentery, and ask the supplier for a QMS Health Declaration.
- Isolate incoming pigs for at least four weeks, with separate equipment and hygiene. Sample any that develop diarrhoea.
- Keep the loading bay at the perimeter, give drivers clean boots, and clean and disinfect the bay after every load.
- Make sure lorries are thoroughly cleaned and disinfected before they leave the abattoir.
- Control rodents and birds.
- Provide boots and overalls for visitors.
The same measures also cut the risk of salmonella, PRRS, and notifiable diseases such as swine fever and PED.
Getting rid of it
Treatment with antibiotics can control disease, but signs often come back when treatment stops. A Belgian study of ten infected farms (Neirynck et al., 2020) found:
Total depopulation
Followed by strict biosecurity: succeeded on both farms that used it. The best chance of success.
Partial depopulation
Succeeded only where biosecurity was followed strictly. It can work on smaller, simpler farms.
Medication alone
Without depopulation, it failed on both farms that relied on it, and may encourage resistance.
Where partial depopulation failed, the main reasons were short empty periods, poor cleaning and disinfection, weak rodent control, and boots and equipment shared between age groups. Successful farms:
- left buildings empty for at least 21 days
- cleaned, disinfected and dried buildings thoroughly
- ran effective rodent control
- used separate boots and equipment
- restocked from dysentery-free sources
The farmer’s commitment to keeping up high biosecurity over the long term was decisive. Plan any eradication with your vet, and use sensitivity testing to choose any medicines.
Swine dysentery in Scotland
In spring 2019, swine dysentery was confirmed on several units on the north-east coast, after Scotland had been free of it for around five years. The Scottish pig industry’s voluntary notification system, through the Scottish Pig Disease Control Centre, was used to alert and support those at risk, and affected businesses were treated. Further cases were diagnosed in England and Scotland during 2021 and early 2022.
Sharing information quickly is what stops an outbreak spreading. Through the Scottish Pig Health Charter, part of the Scottish Pig Health Scheme, producers work together to protect the health status of pigs in their region by raising awareness of new or existing disease threats.
More information
- APHA: Swine dysentery – a threat to the GB pig industry (leaflet, 2022)
- Farm Advisory Service: Swine dysentery – the key facts
- Neirynck et al. (2020): Implementation and evaluation of different eradication strategies for Brachyspira hyodysenteriae, Porcine Health Management 6:27
- AHDB: Swine dysentery
Contains public sector information from the Animal and Plant Health Agency leaflet Swine dysentery – a threat to the GB pig industry (April 2022), © Crown copyright, licensed under the Open Government Licence v3.0. The section “Getting rid of it” summarises Neirynck W, Boyen F, Chantziaras I, et al. (2020), Porcine Health Management 6:27, licensed under CC BY 4.0.