As part of the research, which was unveiled at the ESCMID Conference on Coronavirus Disease, blood works were taken from pets living with symptomatic or infected people during a two-week period.
It discovered that a "substantial proportion of pets” inhabiting Covid-19 positive households had antibodies for the strain.
Professor Dorothee Bienzle, co-author of the study said infected people should isolate from animals as well as humans.
"There is sufficient evidence from multiple studies, including ours, to recommend that SARS-CoV-2 infected persons should isolate from people and animals," she said.
The research was written up after swabs from 18 dogs, 17 cats and one ferret were collected.
The samples were then compared to a control group made up of blood taken from animals before December 2019.