Abstract
Diarrhoeic faeces from about 500 dogs were examined by negative stain electron microscopy. As well as parvovirus, and some of the other recognised viral causes of gastroenteritis, unusual "virus-like" particles were observed in about 8% of the samples. The particles were spherical, 100 nm to 300 nm in diameter, and surrounded by a thick wall penetrated by numerous pores. An additional 74 samples of normal faeces yielded no "virus-like" particles. We do not know the nature of these particles.