Britain is on the verge of a "cat-breeding explosion", according to the RSPCA.
Organisations have urged cat owners to get their pets spayed after neutering levels have dropped to a nine-year low, with over a million cats believed to be unneutered.
Welfare charities are concerned this could lead to a large number of cats roaming the streets.
The RSCPA have estimated that there is around 10 million cats in the the UK and neutering levels are usually around 91 per cent, however, that figure dropped to 86% in 2020.
Many believe the coronavirus pandemic could have played a part due to the increase demand for pets and the lack of neutering options for their owners.
RSPCA’s cat welfare expert, Samantha Watson, said: "During the pandemic these figures dropped to 86% in 2020 - the numbers are beginning to rise again but this still means there are over one million unneutered cats in the UK.
"Although the decrease in neutering is fairly small, this equates to a lot of unneutered cats meaning that we could have a cat-breeding explosion on our hands should these figures decline again.
"Since 2012 the neutering figures haven’t dipped below 90% so it was really concerning to see so many cats not being neutered during the pandemic.
"One of the little known knock-on effects of the lockdown is that there were waiting lists for routine procedures such as neutering due to the impact of the lockdowns on veterinary practises and this may have resulted in a high number of unwanted litters being born which will mean more pressure on rescue charities like ourselves.
"We would urge owners to please get their cats neutered from four months old before they can get pregnant.
World Spay Day is on Tuesday February 22 and owners have been asked to be patient in the wait for their cats to be neutered as vets, like many sectors during the pandemic, continue to be under severe pressure.
A Cats Protection spokesperson urged cat owners to "keep them indoors with plenty to keep them entertained such as toys and scratching posts, until they can be spayed or snipped.
She also recommended: "Owners keep a male and female pair separate, even if they have come from the same litter, this will also help to avoid any unwanted pregnancies."
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