Laboratory diagnostics: Swine dysentery (Brachyspira hyodysenteriae)
What laboratory diagnostic methods can I use to diagnose swine dysentery? Which one should I choose according to the situation? How do I interpret the results?
Swine dysentery is caused by a spirochete called Brachyspira and causes severe inflammation in the large intestine producing bloody and mucous diarrhea.
Alternative names: Brachyspira hyodysenteriae
Swine dysentery is caused by a group of strongly beta hemolytic spirochete called Brachyspira (previously called Serpuline or Treponema) hyodysenteriae (classical agent) and B. hampsonii. These organisms causes severe inflammation in the large intestine producing bloody and mucous diarrhea.
The disease is frequent between 12 and 75 kg, but severe cases occur occasionally in sows and their piglets.
Brachyspira can survive outside the pig up to 112 days, but it dies in 2 days in dry and hot environments. Can be transmitted by birds, flies, fomites and mice.
Spread inside the farm is slow. The number of pigs affected increases as the microorganism accumulates in the environment. Recovered pigs rarely suffer from the disease again, however antibodies (IgG and IgA) do not last long. Therefore, there is not a strong relationship between antibody level and protection. Some sows might not show any symptoms for several months and transmit the disease to their piglets.
The high cost of the disease is associated with mortality (low), morbidity (high), decrease in growth, increase in feed conversion ratio, and the cost of medicated feed.
The incubation period in field cases is normally 7 to 14 days, but it can be up to 60 days. Pigs can initially develop a subclinical carrier state, and afterwards show symptoms if they are under stressing situations or when the diet is changed.
Sows
Clinical symptoms in sows are not frequent, unless the disease appears for the first time on the farm.
Lactating piglets
Weaners and growers
First symptoms are:
As the disease progresses:
What laboratory diagnostic methods can I use to diagnose swine dysentery? Which one should I choose according to the situation? How do I interpret the results?
What happens if the agent that causes swine dysentery is detected, but there is no disease? This is how can it be diagnosed and the consequences to the herd.