The ISPCA is appealing for information after six dead animals were found dumped in a stream in Co Meath.
The carcasses were discovered outside Killallon last Thursday.
One bag contained the body of an adult female white goat, the second the bodies of three male black puppies and the last the bodies of two black female dogs.
None of the animals were tagged or microchipped, and the owner has not yet been located.
The ISPCA said it appeared the animals were not in the water for very long and all were dumped at the same time.
Chief inspector with the ISPCA, Conor Dowling, said it is not known how the animals died.
"We are still waiting to see if we can establish a definite cause of death," he said.
"But the whole circumstances surrounding this discovery suggests to us that there is a sinister element to it.
"This isn't a case of one isolated animal that died and somebody dumped the carcass. These are six animals, different species, different ages.
"This is a pretty sinister find for us."
ISPCA inspector Elaine Whyte, who responded to a call received from Meath County Council, said it was a "truly horrific form of cruelty".
The ISPCA is appealing for anyone who may have information about these animals or the circumstances surrounding their death to come forward in confidence.
The public can contact the ISPCA National Animal Cruelty Helpline on 1890 515 515 or report in confidence online here.