The RSPCA warned today that it will have to shed more than 130 jobs in the face of rising costs and increasing numbers of animals being abandoned during the economic downturn.
The charity said it is under pressure as more animals fall victim to the economic climate, with the number of calls about abandoned animals rising 31% in five years from 21,481 in 2007 to 28,162 in 2011.
Increased fuel costs and veterinary bills are also hitting the animal welfare charity, whose inspectors and other staff drive more than seven million miles a year.
Its fuel bills total £2 million a year and every 1p increase on diesel costs the charity an extra £40,000.
In addition, income has been hit as supporters face hard times, while inflation and a growing staff pension deficit has left the organisation facing "hard decisions".
The RSPCA said it is protecting 1,000 frontline staff, including RSPCA inspectors, animal welfare officers and animal collection officers as well as workers at hospitals and wildlife and animal rehoming centres.
But a staffing review is likely to lead to the reduction of more than 130 posts, particularly in administration and support roles.
Chief executive Gavin Grant said: "The RSPCA is under pressure like never before. Ever larger numbers of animals are falling victim to abuse and abandonment in part due to the economic climate.
"The RSPCA's work depends entirely on people's generosity, and in common with other charities we face greater pressure on our income and more demand for our services.
"I know many of our very generous supporters are feeling the pinch themselves."
He said the charity had already saved million of pounds through cost-cutting measures, but had been forced to eat into financial reserves as the economic downturn had been longer and deeper than feared.
"Some hard decisions must be taken. Significant job losses in administrative areas are sadly inevitable but I will protect frontline animal welfare services."
And he pledged: "Abused and abandoned animals need our help and they will get it. Our policy of 'zero tolerance' of animal abuse and prosecution of the perpetrators will continue."
The RSPCA said that in 2010 it rescued and collected more than 130,000 animals and investigated nearly 160,000 cruelty complaints, treated more than 211,000 animals in hospitals and clinics, secured 2,441 convictions and rehomed more than 64,000 animals.