The RSPCA is trying to trace a man who "dumped" three bald puppies at a veterinary practice a week apart.
Two of the puppies, now named Dobby and Winky after Harry Potter characters, were left in the reception of West Mount Vets, Halifax, on 7 February.
A third pup, Albus, was left on 14 February.
The RSPCA, which said the pups all had mange and were completely bald, said it was concerned the man may have other animals in his care.
Insp Sarah Bagley said: "It's unbelievable that someone has dumped these puppies in this way - not once but twice.
"It's taken a long time for the mange to take hold like this, in fact it's thought these puppies have probably had it for most of their lives.
"I am very concerned about any other animals this person may have in their care."
The "Staffy-type pups", thought to be about four months old, are being treated at an animal centre and it is hoped they can be rehomed once they have recovered.
The RSPCA has appealed for information to trace the man, who was thought to have been wearing a hoodie and tracksuit bottoms.