Body and major organ sizes of young mature microminipigs determined by computed tomography.

To understand the anatomical characteristics of microminipigs, one of the smallest miniature pigs, as a large animal model, we measured the body and organ sizes of four-, five-, six-, and seven-month-old microminipigs (n = 4, females) using computed tomography. In addition, the results were compared with those of young mature beagles (10 months old, two males and three females), which have been widely used as a large animal model. The microminipigs at 4-6 months of age were much smaller than the beagles. However, when the microminipigs reached seven months of age, their overall size was similar to that of the beagles. The thoracic cavity volume of the seven-month-old microminipigs was less than half that of the beagles, and the cavity was largely filled by the heart. The liver size of the seven-month-old microminipigs was approximately half of that of the beagles. Moreover, the spleen of the seven-month-old microminipigs was different in morphology, but not different in size from that of the beagles. In addition, although their volumes were the same, the kidneys of the seven-month-old microminipigs, unlike those of the beagles, were flattened in shape. Collectively, the major abdominal organs of the seven-month-old microminipigs were either the same size or smaller than those of the beagles, but the abdominal cavity volume of the seven-month-old microminipigs was larger than that of the beagles. Thus, the abdominal cavity of microminipigs is assumed to be filled with the gastrointestinal tract. The anatomical characteristics of the young mature microminipigs revealed in our study suggest that microminipigs could have great potential as a large animal model for biomedical research.