The study found all of the bearded men, aged from 18 to 76, showed high microbial counts, while only 23 out of 30 dogs had high counts, and the remainder had moderate levels.

Seven of the men were shown to have bugs hazardous to human health.

The scanners were disinfected after the dogs were examined on the MRI scanner, showing a “significantly” lower bacteria count compared with levels seen when used by humans.

“On the basis of these findings, dogs can be considered as clean compared with bearded men,” said Dr Gutzeit.