Dr Andrew Tucker – Charles Street Veterinary Consultancy
Swine dysentery is a disease that occursworldwide. It is caused by the spirochaete Brachyspira hyodysenteriae. The organism enters the pig via the oral route and starts invading parts of the large intestine about two hours later. Damage and disruption caused to epithelial cells as well as the body’s inflammatory response results in loss of tissue and blood and this is seen as a diarrhoea containing blood and mucous. The disease can be exacerbated by pigs overeating as fermentable food residues then reach the large intestine.
The organism is sensitive to heat, drying and an acid pH but can survive in organic matter for days or weeks. Carrier animals can also harbour and spread the disease for example mice which can carry the organism for 6 to18 months.
How do you know if it’s on your farm?
The most typical and often the first signs seen in a case of dysentery are blood, mucous and later even necrotic material in the faeces. Pigs that recover do so after 1 to 2 weeks and by this stage show marked loss of condition. Production is negatively affected and some pigs remain permanently stunted. Pigs of all ages, sows included, can be affected by dysentery but it is most commonly seen in pigs from 6 to12 weeks of age.
The clinical findings as well as post mortem findings are often enough to diagnose swine dysentery. Various laboratory tests are also available for confirmation.
How do you treat or prevent it?
Swine dysentery is usually introduced to a farm by bringing in infected pigs. It then spreads through the farm via pig to pig contact, slurry channels, gumboots and implements.
Treating the disease is possible with various antibiotics. The response to this method depends a lot on the management systems in place. Continuous flow systems are difficult to treat effectively as are farms with open slurry channels. Cleaning and disinfecting, rodent control, slatted floors and solid partitions all help to reduce the spread of disease.
After an outbreak of dysentery the farm will remain positive unless the farm is depopulated and disinfected or partially depopulated with whole herd medication. There are obviously risks involved with both these methods and thorough planning and strict disinfection are crucial.
Pig Diseases – D. J.T aylor; Diseases of Swine – Straw, Zimmerman, D’Allaire, Taylor