The RSPCA is under pressure to drop its right to bring prosecutions after it spent £22.5 million on legal bills over two years.
An independent review that uncovered the cost also showed that the RSPCA has been paying excessive legal fees.
Lawyers were paid up to £1,200 a day in some cases - highter than the amounts paid to state prosecutors in child cruelty cases.
The review was undertaken by Stephen Wooler, a former Chief Inspector of the CPS Inspectorate.
He was asked by the charity to examine its prosecution policy after several controversial cases, including £326,000 spend on one against the Heythrop hunt in David Cameron's constituency.
Although the case was successful, the judge suggested the public might feel the cash 'can be more usefully employed'.
A key recommendation of the report is for the RSPCA to pass cases straight to the police and the CPS, rather than bringing their own prosecutions.
But, two days after the review was published, the charity launched a prosecution against the Cattistock hunt in Dorset. On October 3, a summons was served to Will Bryer, joint master and huntsman, to appear in court later this month.
Wooler's report found that typical RSPCA payments were £90 to £190 an hour for a solicitor to bring a case in the magistrates court, where a day is up five-and-a-half hours, at a total cost of £496 tp £1,045. This excludes hours spent in preparation. By contrast, a Crown Prosecution Service (CPS) lawyer is paid from £200 to £250 a day, and this includes preparation time.
Fees were even more generous for barristers hired by the RSPCA, with typical payments of £800 to £1,200 a day.
A shocked Mr Wooler said the cases in question would not qualify for the CPS rate for a category B offence - a category that includes child cruelty.