Five bearded dragons dumped in a bin bag at the side of a road in Hampshire would have suffered "weeks of neglect".
The exotic pets were found by a member of the public inside a pink New Forest refuse bag in Whitsbury Road, near Fordingbridge, on 2 April.
RSPCA animal collection officer Jo Blackburn found four of the creatures still alive but the other had died.
Vet David Holah said the owners "failed to give them even the most basic care". The RSPCA has appealed for information.
Ms Blackburn said: "Two of them were thin and the other two were emaciated.
"They were all cold and dehydrated but we hope with the specialist care they are getting that they will pull through."
The bearded dragons are being treated at Lynwood Veterinary Centre.
Mr Holah said: "For them to have got into such a poor state it would have taken weeks of neglect and since there was no underlying medical cause we are talking about someone failing to give them even the most basic care.
"Sixty per cent of the animals I see are exotic pets like these and the problems are usually caused by poor husbandry or lack of knowledge on the part of people that take them on."