The stag came out of the sanctuary area and entered a street at Kodiakarai in search of water when the dogs pounced on it, they said.
The stag sustained severe injuries on its stomach.
Onlookers chased the dogs away and brought the stag to the Veterinary hospital at Vedaranyam. However, veterinarians declared it brought dead, officials said.
Every year during summer, the sanctuary faces acute water scarcity.
The rising temperature, coupled with dry coastal wind, create a drought-like situation and with most of the sanctuary's natural water resources drying up, animals stray into human habitation in search of water and fall prey to dogs, officials said.