We first told you about the dog, named River earlier this week after a fisherman found the animal, dumped in the Arkansas River.
Veterinarians and police say River had all the signs of abuse appearing to have been tied down and dumped in the water.
They worked for days to help river get back into shape. But his recovery took a turn for the worse on Saturday, when River passed away after a seizure.
Now, the death is under investigation as an animal cruelty and neglect case, which is a felony in Arkansas.
Call (501) 851-6219 if you have any information.