The union has voiced concerns about a "culture of bullying" at the animal charity as the two organisations take part in discussions about the charity’s plans to introduce a new pay scheme for its staff.
The charity’s own internal staff satisfaction survey found that 31 per cent of staff members had experienced or witnessed bullying behaviour at the organisation, the union said on Monday.
In response, the charity said in a statement that it had policies and procedures in place to help safeguard staff and had launched a "wellbeing action group with Unite to review all relevant policies and explore fresh ways to ensure that anyone can raise a concern and access support".
It said that in response to the satisfaction survey its board had also recently approved a new people and culture strategy focused on employee wellbeing.
But in a statement Unite told Third Sector: "The wellbeing action group was discontinued because of the lack of progress in creating dedicated policies that addressed bullying and mental health issues in the workplace."
The RSPCA denied this, saying the group was "currently paused so it can be expanded to include a wider range of people and become more effective in addressing wellbeing issues", and that it had made progress on policy creation.
The charity said the wellbeing group "has worked with Unite to develop a respect policy that confirms the society's commitment to being an inclusive and supportive place to work. It provides a clear statement of the society's commitment to diversity and inclusion, and a zero-tolerance approach to all forms of bullying, harassment and discrimination.
"This policy is to be presented at the board this week and will be launched society-wide after approval."
A Unite statement had also claimed that there "continues to be no internal policies that deal directly with bullying or harassment" at the RSPCA.
The charity said in response that there was "no place for bullying of any nature within the RSPCA" and insisted that there were already policies and procedures in place "to help safeguard staff and protect their wellbeing".
The statement said: "These include the employee code of conduct, grievance and disciplinary policies."
The animal charity and the union are currently in talks about plans to introduce a performance-related pay scheme for salary increments for all of the RSPCA’s 1,700 staff.
Third Sector understands that, if an agreement with the union cannot be reached, staff will be dismissed from the charity if they do not sign the new contracts by 31 March next year.
The union has accused the charity of not providing enough detail for the talks to be successful, a claim the RSPCA has denied.
The union has called on the charity to honour a previously planned incremental rise, due to take place in April, and to extend the negotiation period to allow for more discussions.
Chris Sherwood, the charity’s chief executive, is due to make a decision tomorrow about whether to extend the talks or press ahead with the new contracts, according to the union.