This is a sporadic disease seen in newborn pigs. Usually more than one pig is affected in a litter. If the tremors are too great for the piglets to find a teat and suckle then mortality maybe high. Mortality in an affected litter or in a herd outbreak could increase above the norm by 3-10%. The condition decreases as the affected piglets grow.
It would be unusual to find a pig farm that sometime in its history had not experienced one or more litters of trembling piglets. There are 4 possible group causes. The causal virus in group 2, which is by far the commonest cause, is widespread among most if not all pig populations, yet little disease is seen in most herds, presumably because an immunity is established in the sow herd. In new gilt herds however, there can be major outbreaks involving up to 80% of all litters during the first parity. This is an unquantifiable risk in any new gilt herd.
Symptoms
Sows, Weaners & Growers
- N/A
Piglets
- Muscle tremor, only seen when piglets are walking around and not when they are asleep.
- Nervous symptoms i.e. shaking of the body.
- Incoordination.
- Often dog sitting.
- Increased mortality in piglets.
Causes / Contributing factors
The causes of the condition are classified into 4 groups based on brain histology.
- Associated with a classical swine fever.
- Caused by an unknown virus, possibly circovirus type 2. Most of the problems in the field are found in this group.
- Associated with either hereditary disorders seen in the Landrace or Saddleback breeds or with organophosphorus poisoning.
- Includes aujeszky’s disease and Japanese encephalomyelitis virus.
Diagnosis
This is based on clinical evidence although histological examinations in the laboratory can help to differentiate the groups.