Cat owners must have their pets neutered to cut the spiralling number of unwanted and stray animals, according to a new RSPCA campaign.

New research commissioned by the animal charity will help it target areas where cat populations are rising fastest, it claimed. With every female cat able to produce a potential 50 million descendents in its ten-year lifespan, the problem is potentially huge.

Southampton University

The society's £1.5 million scheme uses a computer model, designed by Southampton University experts to forecast feline numbers in key areas. The hi-tech system will show how many cats must be neutered there, first to cut numbers to normal levels and then to keep them stable.

Owners will then be offered cheap neutering schemes at private veterinary practices, mobile clinics and at RSPCA offices. Microchipping will also be offered at the reduced rate of £5 to those who have their cats neutered.

The RSPCA estimates that one un-neutered female could be theoretically responsible for 50 million offspring if none of her female descendants were neutered. It said a female with an average lifespan of 10 years has two litters of six kittens each year, containing two females per litter, which can then go on to reproduce and increase the family tree at an exponential rate.

"In reality it doesn't happen like that, because most cats are neutered, but it shows how quickly things can spiral if nothing is done," a spokeswoman said.