Concerns have been raised about a new craze of keeping African pygmy hedgehogs as pets.
The RSPCA says the exotic animals are a considerable commitment and would need a large temperature-controlled enclosure to mimic where they come from in the wild with space for digging, foraging and exercise.
RSPCA exotics senior scientific officer Nicola White said: "It is difficult to adequately meet the animal's needs in a household environment and, where these needs can't be met, the animal really should not be kept."
The warning about the craze comes after one hedgehog was found abandoned at a London Underground station.
The hedgehog, now named Paddington, was spotted in a hamster carrier at Edgware Road on August 11.
RSPCA animal collection officer Jill Sanders said: "I was relieved that the little hedgehog was still alive as it was far too cold for him.
"He was crammed into a tiny cage and must have been very disoriented and frightened."
It is not clear if someone accidentally left the animal behind or abandoned it on purpose.
The animals would need an enclosure of between 24C to 30C. Anything hotter and the animal is likely to suffer heat stroke while a temperature lower than 18C can induce torpor, a form of hibernation, the RSPCA warned.