Swine Dysentery


Other names

Blood dysentery, bloody scours

Causal agent

Bacterial Brachyspira hyodysenteriae (formally known as Serpulina hyodysenteriae). 12 serotypes are known

Age group

Typically affects pigs from 15 to 70 kg

However, in acute outbreaks in naive herds it can affect all age groups from suckling piglets to adult sows

Clinical signs



Swine Dysentery-acute 02 sw

Diarrhoea - with or without blood, and severity is very variable. A careful search of the pen normally reveals the presence of blood and mucus in some places

Diarrhoea with large amounts of mucus in faeces and afterwards with flecks of blood

Death of one or two pigs before other pigs show any signs

Rapid loss of condition in some pigs and pigs look hairy

Clinically affected pigs in a group can reach 50%

Reduction in FCR of 0.6 while disease present with extension of finishing by 20 days

On established herds

Dehydration, pigs with a painful abdomen and some pigs weak and incoordinated

The disease appears to be cyclic and reappears at 3-4 week intervals


Pigs may transmit the bacteria for 90 days

Brachyspira hyodysenteriae survives in:

Faeces for 61 days at 5C

Soil for 18 days at 4C

Flies for 4 hours

Mice can shed for over 180 days

Cats and dogs can carry for 13 days

Incubation period

Incubation period 10-14 days

Common differentials



PIA - Haemorrhagic Porcine Intestinal Adenomatosis - Ileitis

Other Brachyspira spp can cause very similar signs, including the mortality.


Post-mortem Lesions

Confined to the large bowel - caecum, colon and rectum

Reddening to haemorrhage of the large bowel

Post-mortem findings

Typical changes in the acute phase include hyperaemia and oedema of the walls of the large intestine. Colonic submucosal glands may be more prominent and appear white. The mucosa is usually covered by mucus and fibrin with flecks of blood and the colonic contents are soft to watery and contain exudate. The photograph represents a severe case with extensive haemorrahge into the colon.


Isolation of Brachyspira hyodysenteriae in the faeces. Note there are a number of other spirochetes that are normal in the pigs' large bowel and other may be associated with colitis syndromes.

PRC is available and may be used on faecal samples. Immunohistochemistry can be useful on tissues samples.


Acute outbreak

Treatment via the water supply is essential for acute cases of swine dysentery as the affected pigs will not eat and to all animals in drainage contact

Follow by in-feed medication once pigs start to eat, to all affected pigs and all animals in drainage contact

Very sick and weak pigs respond better using injection antibiotics

Water supply should be supplemented using electrolytes

Herd eradication

Eradication protocols




without total


Requires detailed preparation and attention to detail

Attempt in the late spring/summer

Reduce herd size to as small as possible consider a partial depopulation

Have an effective rodent control programme

Drain all slurry pits

All buildings not containing pigs should be cleaned, disinfected and fumigated

Medicate all remaining pigs as prescribed

After 1 week of medication all equipment used for handling pigs, feed and manure should be cleaned and disinfected

Clean and disinfect floor as often as possible

Treat all farm cats and dogs as prescribed

Spread of swine dysentery

Pigs Purchased only from Swine Dysentery free herds


Boots, clothing, stockpeople

Truck wheels

Rats and Mice