GETTY42,660 mice were experimented on last year at Cardiff University
The researcher was carrying out tests when the laboratory mouse sunk its teeth into him.
And after suffering an extreme allergic reaction, the lab technician was rushed to hospital.
The mouse bite attack took place in a lab at Cardiff University - where 42,660 mice were experimented on last year.
Concerns have now been raised over health and safety in the animal testing laboratories.
A university spokeswoman said: "The university has a duty of care to all staff working with animals and takes health and safety seriously.
GETTYA spokeswoman confirmed the university takes the health and safety of its staff 'very seriously'
The university has a duty of care to all staff working with animals and takes health and safety seriously
"Rigorous procedures are in place to ensure a safe working environment and all staff are encouraged to report animal bites, regardless of whether they are considered occupational hazards.
"In 2017, an experienced animal technician suffered an unexpected anaphylactic shock after being bitten by a mouse.
"The incident was dealt with immediately by the university, and the individual hospitalised as a precaution. The individual has fully recovered."
She added there were concerns over the outsourced occupational health provision at the university.
The spokeswoman said: "Cardiff University is committed to providing open and transparent information about our research involving animals and our standards of animal care and welfare."
GETTYA total of 46,743 animals were experimented on last year at the university
The university added it was fully compliant with the Animals (Scientific Procedures) Act 1986.
The information was unearthed by campaigners Cardiff Animal Rights.
A spokeswoman for the group said: "It is absolutely not acceptable the amount of distress caused to living beings here. We call on Cardiff University to move forward and stop the cruelty and killing.
"There are a great many organisations that concentrate on medical research that do not use animals, as they are aware of the detrimental impact.
A total 46,743 animals were experimented on last year at the university - including four rabbits, two guinea pigs, 122 frogs and 1,825 fish.