Astrovirus-like, coronavirus-like, and parvovirus-like particles were detected through electron microscopic (EM) examination of loose and diarrheal stools from a litter of beagle pups. Banding pattern obtained from equilibrium centrifugations in CsCl supported the EM identification. Densities associated with the identified particles were: 1.34g/ml for astrovirus, 1.39 g/ml for 'full' parvovirus, and 1.24-1.26 g/ml for 'typical' coronavirus. Convalescent sera from pups aggregated these three particle types as observed by immunoelectron microscopy (IEM). Only coronavirus-like particles were later detected in formed stools from these same pups. Coronavirus and parvo-like viruses are recognized agents of canine viral enteritis, however, astrovirus has not been previously reported in dogs.