The RSPCA has found 269 animals living in "utterly disgusting" conditions in a three-bedroom house.
Inspectors acting on a tip-off from the public discovered 244 dogs, seven cats, a rabbit, a chinchilla and a variety of exotic birds. As they searched the house in Carnforth, Lancashire, owned by a middle-aged couple, animal welfare experts found every room, from the basement to the loft, "full to the brim with animals".
Some of the worst neglect was suffered by the dogs, which were all small breeds, including shih-tzus, dachshunds, lhasa apsos, bearded collies, corgis, chihuahuas, poodles, Pekinese and Yorkshire terriers.
The RSPCA is treating 47 dogs found to have matted coats, sores, mites and fleas at a centre in Great Ayton, North Yorkshire. Others were suffering from eye and ear conditions and one had an eye removed immediately after the raid on 10 September.
Among the birds were a macaw, an Amazonian parrot and an African Grey. There was none from an endangered species. The RSPCA sent inspectors accompanied by a dog warden from Lancashire County Council. About 25 animal welfare experts worked for two days removing the animals and fitting microchips in their necks for identification.
Most of the animals had been well fed, one inspector. said. "They all appear to have had a decent diet, which for the owners' point of view must have been as expensive as it was time-consuming."
The owners were co-operating with the inquiry and would be asked to relinquish ownership of the animals.
The RSCPA has declined to name the couple or give their address because that may prejudice a possible prosecution. In previous successful cases brought by the RSPCA courts have forbidden offenders from owning pets.
Hamish Rogers, chief superintendent in the RSPCA's prosecution department, said in most such cases pets were hoarded by sufferers of obsessive compulsive disorder.
Although the RSPCA had dealt with larger numbers of animals such as an abandoned flock of sheep, this was the largest seizure of domestic animals. "We haven't come across anything like this in the past," Mr Rodgers said.
"It is a type of obsessive compulsive disorder that certain individuals have. A lot of them believe they have a special ability to care for the animals who they believe can't survive without their input and the situation gets out of control. Many of the animals are not neutered and so they breed indiscriminately, then the keepers cannot afford to take them to the vet and it becomes part of a vicious cycle."Reuse content