They have never scampered across a lawn, romped through woodland or stretched before an open fire. Next month more than 500 dogs and cats bred in captivity in a research facility in Mayo will start down the path to freedom when their transfer to Ireland's biggest animal rescue charity begins.

The American multinational, which has been picketed by animal rights campaigners, decided to release the dogs rather than euthanise them after announcing the closure of the Glenamoy facility. Twenty staff have been let go but kennel staff have been retained to look after the animals until they are ready to embark on their new lives. A second facility in Ballina will remain open.

The company confirmed this weekend that dogs at its Mayo facility have been euthsanised for research. A local authority inspection last year reportedly counted 619 dogs at the facility. A Charles River spokesperson said the reduction to 350 dogs "is due to animals being used for the development of new veterinary pharmaceuticals".

She later clarified that dogs were euthanised in the course of "research".

Bred for the sole purpose of scientific research, the remaining animals were raised in the confines of the plant.

Dr Andrew Kelly, chief executive of the ISPCA, said he understands the animals were used for non-invasive tests for common veterinary medicines such as worm and flea treatments.

Despite the concerns of animal rights organisations, he said the animals were "happy and in good health" in living standards better than at some puppy farms.

"I can tell you I visited the site and met all the dogs. They were all very well socialised, very confident, coming up wanting to say hello, wagging their tails," he said. A few were "slightly less confident than the others", he said, but that was not unexpected. Animal behaviourists have been on site to assess the dogs before release. "For example, they won't have been walked on a lead... That's a basic thing that's learned very easily," he said.

"Some of the dogs might need some help with building their confidence around people because they wouldn't necessarily have seen people that often. Some dogs will adapt very quickly and some will take a little more time."

The ISPCA, with the help of Dogs Trust and Cats Protection, hopes to re-home all of the animals in Ireland and the UK within six months.

Charles River said it has "a deep commitment to animal welfare" and "strong record of compliance with global regulatory agencies".

"Our work is an essential component of research that leads to new discoveries and plays a vital role in virtually every medical advance for humans as well as animals. We only work with animals to help our clients develop new therapeutics for patients that need them."

Mice, sheep and birds also used in procedures

New figures show that 226,393 animals were used in tests in Irish laboratories last year. The vast majority - 190,585 - were mice but rats, guinea pigs, dogs, cats, horses, sheep, goats, cattle, birds and fish were also used.

Some 122 dogs were used in 587 procedures last year, while 76 cats were used in 164 procedures.

The tests on dogs and cats were for research into the development of veterinary medicines and were classed either as “mild” (such as injection or short period of isolation) or “moderate” (involving procedures such as surgery, repeated injections or blood tests).

One cow, two pigs, 10 rabbits, 551 rats and 61,456 mice were involved in procedures classed as severe.

Almost 4,000 animals, mice, rats and guinea pigs, were humanely euthanised under anaesthetic at the end of the procedure.

Some 157,872 tests were necessary under EU law to test the safety and potency of medicines. The animals used were largely mice.

The figures are published by the Health Products Regulatory Authority, which promotes alternatives to the use of live animals where possible.