Swine dysentery
Syn: Brachyspira hyodysenteriae infection
DD: Lawsonia intracellularis (proliferative enteritis/ileitis), Brachyspira pilosicoli (intestinal spirochaetosis; spirochaetal colitis), Non-specific (dietary) colitis; less commonly: Salmonella,Whipworm (Trichuriasis), Gastric ulcers.
Brachyspira hyodysenteriae (formerly Serpulina hyodysenteriae) is a relatively common pathogen with a severe impact on production. Swine dysentery can occur in any age (suckers - breeders) but is most common in 15-70 kg grower pigs (5-20 weeks). It may be less common in weaners if medication for respiratory diseases is used.
Clinical expression is normally low mortality/ high morbidity, and affected pigs can vary from the classical mucohaemorrhagic diarrhoea - various amounts blood and mucus, or faeces varying from soft, grey to light brown to dark. Severe cases can show watery faeces, with blood and mucus, and stained hindquarters. Swine dysentery may be difficult to detect in straw-based shelters. A less severe, chronic form of loose, dark faeces ("black scour") is associated with intermittent medication.
History is typically one of depressed growth rate, and partial loss of appetite that further decreases growth. There is gradual spread within a group, and increased incidence of "slab sided" pigs (hollow in flanks). Abattoir inspection may reveal an index case through evidence of an accumulation of blood-tinged and jelly-like material in the large intestinal wall and between the coils, linked to a history of "ordinary" growth rate.
Pathology affects proximal large intestine, causing a fibrinohaemorrhagic colitis and typhlitis. This is often severe and extensive, with erosions, fresh blood and mucus on necropsy. Epithelial hyperplasia is a feature.
Diagnosis
Gross and histopathology. Smears of affected intestinal mucosa. Identification of Brachyspira hyodysenteriae infection in individual animals by PCR on affected intestine or faeces. Culture of affected intestine or faeces.
Specimens required
Live pigs:
- Faeces for PCR
- Faeces for culture if isolation is required (e.g. for antibiotic sensitivity). It is preferable to advise the laboratory so special selective media can be available.
Note: PCR are available for Lawsonia intracellularis and Brachyspira pilosicoli. Serology is available to exclude Lawsonia, if clinical signs have been evident for over one week.
Dead pigs:
- Fresh, chilled portion of affected gut for smears, PCR and possible culture.
- Fixed affected intestinal section in buffered formalin for histopathology.