Canine couture has become fashionable in recent years and there is a dizzying array of products on sale, from bootees, pyjamas, all-in-one trousers and even hoodies for dogs.
Top fashion designers, including Vivienne Westwood and Ben de Lisi, have also created dog designs, while the London store Harrods has an annual fashion show called Pet-a-Porter.
Experts believe there are occasions where dog clothing is acceptable, such as with small dogs and short-haired varieties, and during cold weather.
Jess Bland, a professional dog walker and pet sitter, says: "Dog clothing certainly serves its purpose when it's cold and wet, but it has to fit properly.
"Although dogs would survive in the wild, they're generally used to being indoors. So there is a case that they need coats in the winter, especially shorter haired dogs and smaller dogs."
But the fashion for pet clothes angers Lynn Williams, founder of dog charity Happy Dogs. She said: "People love their pets and the retail trade has latched on to that.
"To see a little dog dressed up in boots, I think, is a little over the top.
"You can buy anything fashion wise for your dog. I have an extreme love of the dog, but I don't like to see them dressed up as little human beings. I don't think they like it either. It's unnatural."
Jo Barr, RSPCA spokeswoman, said: "Dog owners should be aware that under the Animal Welfare Act that came into force in April 2007 they have a duty of care to ensure that all of their pets' needs are met.
"One of those needs is to express normal behaviour and it could mean that with restrictive clothing they are not able to do that properly.