Putative peripheral neuropathy in suckling piglets.

Abstract

Over a period of almost 2 years, a progressive motor disturbance was found to occur in 20-50% of the litters of both primiparous and multiparous sows in a large pig herd of 1000 sows. The motor disturbance sometimes affected the entire litter; however, in most cases only a few piglets per litter were affected. The clinical signs appeared at 3-5 days of age and consisted of difficult movement followed by anteflexion or retroflexion of the tarsal joints or 'rabbit-like posture'. Subsequently, primarily after weaning, inflammatory and necrotic lesions developed on the paralysed limbs as a result of secondary infections of injuries. The tibial nerve and the common fibular nerve of recently affected (5- to 6-day-old) piglets showed degeneration, demyelination and necrosis of some of the nerve fibres, accompanied by restorative changes in more chronic cases. The central nervous system, bones, skeletal muscles, tendons and joints showed no lesions that could have accounted for the symptoms of motor disturbance. Aetiological investigations excluded the possibility of lead, copper and cadmium toxicity. Vitamin B2 administered orally at 1 day old proved to be ineffective. The disease did not develop in piglets of sows kept at another farm under the same management and fed a diet prepared according to an identical formula from the same ingredients as those used on the affected farm, but with no milk whey added. This raised the suspicion of triaryl phosphate (TAP) poisoning, but this was found not to be the cause of the disease. New boars had not been brought to the farm in the year preceding the onset of disease, and the disease could not be linked to a specific boar or boar line. The aetiology of the disease has remained unclear.