RSPCA chief executive Gavin Grant said prosecution for animal cruelty is "always a last resort".
Figures released by the charity today showed the levels of neglect, which has risen by a third in England and Wales. He said:
Our inspectors investigated 150,833 suspected cruelty cases and issued 78,090 advice notices last year - these are extremely effective in improving the care of animals.
However if there is evidence of a crime and serious animal abuse then we will take legal action to protect the animals and prevent further abuse.
We also want to see judges taking these offences far more seriously.