Learn More About a Disease

Swine dysentery

Swine dysentery is a highly contagious disease in pigs. It is caused by bacteria called Brachyspira (Serpulina) hyodysenteriae. It lives in the colon, and causes degeneration and inflammation of the intestinal mucous membrane, but at certain stages of the disease cycle, bacteria can be present in the cells that line the intestine. The cost of swine dysentery has been estimated at least $7 to $8 per pig in infected herds. It is therefore an expensive disease that cannot be ignored.1

However, the presence of the disease in North American farms has greatly diminished since the 1990s. This is partly due to the establishment of reproductive herds free of the disease and to certain farm methods, such as medicated early weaning, which have helped to control or eliminate the disease.

Clinical Signs +

The incubation period for swine dysentery is variable. Initially, infected animals seem listless and have a decreased appetite. The acute form of the disease is characterized by diarrhea, and the animal may show signs of abdominal pain. In serious cases, the diarrhea contains blood and mucus, and the animal can die from dehydration. If the disease is well established in a herd and is therefore more chronic, effects such as slow growth and decreased feed conversion efficiency become evident.

Transmission +

Swine dysentery can be transmitted in any herd following the introduction of an infected animal. The pathogen is excreted in feces and can be transmitted in various ways, in particular by contaminated vehicles or boots. Rodents can also carry the bacteria and contribute to its transmission. Even after a pig has recovered, the bacteria can be excreted in the animal's feces.

Diagnosis +

The diagnosis of swine dysentery can be based on clinical signs and an examination of characteristic pathological lesions in the large intestine. However, this may not provide conclusive evidence, as other illnesses that may accompany swine dysentery could be confused with the actual disease. The detection of potentially pathogenic spirochetes in the feces of an affected pig must be an integral part of the diagnosis in the case of bloody diarrhea in weaned piglets. Samples obtained during an autopsy of infected animals can be sent to a laboratory to isolate and identify Brachyspira hyodysenteriae. Examinations that can be used to identify swine dysentery are histopathology, an intestinal or fecal culture swab and PCR (Polymerase Chain Reaction).

Treatment +

Infected pigs must be treated as quickly as possible. An effective therapeutic profile generally includes treatment in the drinking water of infected animals, followed by treatment in the food for the rest of the herd to prevent transmission of the disease. If the animals are unable to eat or drink, an injectable antibiotic should be used. Antibiotics are effective if they are administered in the early phase.

Consult with your veterinary doctor before administering antibiotics and vaccines to animals.

Your veterinary doctor is the best source of recommendations that are truly suited to your farm.

Prevention +

Several procedures must be applied for effective control of swine dysentery: administer a treatment in water or food; clean and disinfect shelters; if possible reduce the population density; isolate animals and do not allow herds to mix. Rodents can act as disease carriers, and controlling the rodent population is very important. There are also methods for eradicating the disease from a herd. 


1 Swine Health, Canadian Swine Health Board, Number 3, April 2012