Vets and rescue centres are begging cat owners to neuter their pets to tackle the exploding population of stray felines.
A Radcliffe-on-Trent vet claimed there were so many un-neutered strays on the streets of Nottingham that animal shelters could not cope with the growing number of unwanted kittens.
Erica Coleman-Field, from All Creatures veterinary centre, said: "There are so many strays on the streets who are mating with other strays and creating pools of unwanted kittens who end up carrying disease.
"The shelters are full, re-homing centres are full and everyone is doing their best but the problem is huge."
Cats Protection said the number of stray cats locally was on the rise and encouraged people to look at the charity's voucher scheme, which offers free or discounted neutering for pets.
Roz Cresswell, acting manager of the charity in Nottingham, said: "One female cat could in theory end up being responsible for 20,000 cats, with each litter more likely to be females than males and kittens being able to breed from a young age.
"Getting cats neutered is better for their health and means they are less likely to get diseases."
Figures from the RSPCA showed 85% of litters were unplanned and many owners mistakenly think cats should have one litter before they are neutered.
The charity also said that despite the traditional age for neutering being six-months-old, cats can reach sexual maturity as early as four months so owners should think sooner about getting the procedure done.
RSPCA chief veterinary officer, James Yeates, said the charity's centres had hit "crisis point" because of the number of cats coming in.
He said: "The answer to the cat crisis lies in loving cat owners neutering their cats before they can get pregnant.
"Sadly one of the consequences of not neutering your cat means more and more cats are being brought into rescue centres as there is a shortage of available good homes for them.
"We would urge owners to get their cats neutered. Neutering cats as soon as possible is extremely important to prevent unwanted litters and to help stop male cats from wandering and getting into fights."
Jenny Stavisky, a clinical lecturer based at the Centre for Evidence-based Veterinary Medicine at the University of Nottingham, carried out research into the burden of un-owned cats across the UK which showed the huge population problem both locally and nationally.
She said: "Our research has shown that over 150,000 cats enter rescue shelters in the UK every year. Most of our local shelters are full to bursting with kittens and older cats looking for homes.
Dr Stavisky said the problem had grown even larger since the economic crisis began.
She added: "When people are under financial strain, they can really struggle with the cost of keeping a pet, and when jobs are lost or people are forced to move to rented accommodation they can find it difficult to keep their pets.
Dr Stavisky also pleaded with pet owners to get them neutered for the good of the animal.
She said: "My advice would be to get your cat neutered. It is a very safe, quick procedure and it's in your cat's interests -neutered cats are healthier and live longer.
"If you are keen to have kittens in your house, a good alternative is to offer to foster for your local rescue shelter, as many use the help of volunteers to keep litters in their homes until they are old enough to be re-homed."
