Three Beagle bitches were experimentally inoculated with between 28 and 36 Pneumonyssoides caninum mites. The bitches were housed together with a male Beagle for up to 33 weeks and mated when were in heat. The aim of the experiment was to study if transmission of P. caninum from the bitches to the puppies took place. Whelping occurred between 10 and 34 weeks post inoculation (p.i.). Two bitches were kept isolated with their litters until the puppies were 8 weeks old. They were then euthanised and necropsies performed. The third bitch had only 1 puppy born alive which died after one week. At that point, the bitch was euthanised and necropsies were performed. Two to 4 P. caninum mites were found in the inoculated bitches 18 to 42 weeks p.i. but no mites were found in their offspring. Thus, the transmission of P. caninum infection is still unknown.