Is the piglet a useful animal model of sudden infant death syndrome?

A prospective study of early death was conducted in a large population of piglets in order to investigate the causes of mortality and determine whether this species could be useful as an animal model of the sudden infant death syndrome (SIDS). 1,921 live-born piglets were closely monitored from birth to 2 months of age. The cause of death was analyzed in all the animals which died during this period. Complete histological, bacteriological and virological examinations of all sudden death animals were compared to identical examinations performed in age-matched control animals. 384 animals (20%) died during the study period and 8 sudden deaths were observed (0.4%). The principal causes of nonsudden death were overlaying (9.4%), hypotrophy (6%), infection (2%) and acute fetal suffering (1.4%). Bacterial infection was found in 6 of the sudden deaths. There was 1 case of suffocation and 1 unexplained sudden death. Compared to controls, there was a significantly greater prevalence of pathology (p < 0.01) and of positive tissue bacteriology (p < 0.05) in sudden death animals. The 6 sudden deaths due to bacterial infections were clearly different from the human syndrome. Suffocation is a known cause of sudden infant death. In the final analysis, only 1 animal (0.5/1000) had an outcome which could be assimilated with SIDS. It is concluded that although there probably exists a syndrome in the piglet equivalent to SIDS, its incidence is very low and major obstacles related to the high level of early mortality in this species hinder investigation.