London - They are the latest trend for cats and dogs stick-on "nails" that make it look like they have had their claws painted.
But the growing popularity of the plastic covers has triggered something of a catfight.
Pictures of cat owners posing with nails matching those of their pet have become commonplace on Facebook, Twitter and Instagram.
However, a leading UK animal welfare charity claimed that the claw covers are cruel and suggested they are being used to turn pets into fashion accessories.
It said that they stop cats carrying out their natural behaviour, such as scratching. Vets also criticised the trend. But one of the firms that sells the claw covers rejected the accusations as did several pet owners.
They say that far from being cruel, the plastic covers stop a cat shredding furniture and scratching their owners' arms and legs. They also stop cats harming themselves by scratching excessively, manufacturers say.
British Veterinary Association senior vice president Sean Wensley said: "Our pets are not fashion accessories. Not only can nail varnishes, and the adhesives used for sticking claw covers, potentially be toxic for cats and dogs, but claw covers prevent cats from retracting their claws, which can be distressing and painful.
"Scratching is a normal and necessary part of a cat's behaviour. Pet owners worried about their cat scratching household furniture should provide alternatives, such as scratching posts. If you're struggling with your cat's behaviour, speak to your vet."
Most cats have five claws on their front paws and four or five on their rear paws. The fifth front claw is the thumb-like dewclaw, which helps provide better grip while climbing. Cats scratch hard surfaces to sharpen their claws and to leave a scent.
Daily Mail