RSCPA workers are concerned about their jobs
Staff at the RSPCA's Welsh headquarters walked out on Tuesday lunchtime in protest over proposals to close the office.
The threatened closure - brought about losses on the charity's stock market investments - would mean the loss of 25 jobs.
The charity's governing council is holding key talks on Tuesday and Wednesday to discuss re-structuring. One of the proposals is to close the Brecon administrative centre.
It is believed one option would be to merge the operation in Wales with western England and have a combined headquarters at Shrewsbury.
Another option is to keep Wales as one whole region.
After suffering heavy losses on the stock market, the RSPCA decided last October to freeze staff pay and all capital projects for 12 months.
The concern is not only about jobs but also how effectively animal welfare in Wales could be managed from England
Kevin Manning, RSPCA Superintendent
The RSPCA's Superintendent for Wales, Kevin Manning, said: "Staff staged the lunchtime walkout to show their strength of feeling and depth of concern about the threat of closure facing the Brecon premises.
"The concern is not only about jobs but also how effectively animal welfare in Wales could be managed from England," he added.
Mr Manning stressed animal welfare had not been put in danger during the walkout because some staff had stayed behind to man the phones.
Staff at Brecon include a team of telephone controllers, who work on a 24-hour shift; a press officer, education officer, public affairs officer, manager and a team of audio typists.
Animal welfare was not put at risk by the walkout
Commenting on the staff action, an RSPCA spokesman said: "We would say that the RSPCA is a democratic organisation and staff, who are understandably worried about their jobs, are entitled to express their views."
The spokesman added that no decisions had been taken yet about the future shape of the organisation.
"The review is intended to streamline the organisation, and to minimise the impact of the still volatile stock market on our reserves," added the spokesman.
"The ability to change with the times is crucial to the survival of any healthy organisation, and evolving structure has been the hallmark of almost 180 years of successful RSPCA operations.
"The current economic climate has now provided an opportunity and impetus to review the administrative structure and to maximise efficiency."
The spokesman added that savings in management costs are being proposed to protect vital front line services.
He added that whatever decision the ruling council makes, the RSPCA would still operate in Wales.