Dog owners were sending their pets for "training" at a premises which has now been raided as a suspected puppy breeding farm.
Gardaí in Co Louth confirmed they will be preparing a file for the Director of Public Prosecutions after the premises was searched.
Some 38 dogs were found there - including 23 bitches and eight puppies - mostly German Shepherds. There was also a French bulldog, a labradoodle and a golden retriever. Pure-bred German Shepherd pups are advertised for sale for around €800 while an adult dog can cost more than €2,000, according to some online advertisements.
A closure order was served on the operation, which is in a rural location, by the Louth county vet Garrett Shine.
Louth SPCA inspector Fiona Squibb said they attended from a welfare point of view, and she described the dogs as being "kept in pure filth".
One cage measuring approximately two metres by one metre was holding two adult dogs.
Dog wardens were last night trying to trace the owners of animals that had been microchipped and registered.
It also appears that some of the dogs were there without the owners' knowledge.
One man said he had sent his dog because it was advertised as providing training for dogs.
His nine-month old labradoodle had been there for three weeks when it was searched on Monday afternoon.
When he went to get it from the pound yesterday, he said, "it absolutely looked like it had been straying for three months and as if it had rolled in cow s***e".
In a statement Louth County Council said: "As part of the operation, 38 dogs including two litters of pups were removed from a property in the area and taken to Louth County Council animal pound where they have been documented, scanned and vaccinated."