Cool question. First, there are no warrior-dog remains from any battlefields. It is very hard to find ancient battlefields at all, and barely anything survives even when we can pinpoint them.

As far as I know, there is no solid evidence for the use of dogs in warfare in the Roman period. In the Greek period, I can think of an example of dogs seeming to participate in some way in a battle on the famous terracotta sarcophagus from Clazomenae in the British Museum, 510-480 BCE. See here and here. It's not clear exactly what the dogs are doing, but they seem associated with cavalry.

In Homer Iliad 23, Akhilles cuts the throats of nine dogs and adds them to the funeral pyre of Patroklos (ἐννέα τῷ γε ἄνακτι τραπεζῆες κύνες ἦσαν, 173, "nine dogs 'of the table' there were for the lord [Patroklos]"). These "dogs of the table" (it's an adjective) seem to be less desirable than hunting dogs according to Odyssey (19.306ff): "Eumaeus, it's odd that this hound lies here in the shit. He's a fine animal, but I don't know for sure if he has the speed to match his beauty, or if he is merely one of those 'table dogs,' which lords keep around for show.” They obviously have value, because they are sacrificed in a series with costly sheep, jars of honey and oil, and Trojan young men (human sacrifice). At the very least, we can say that the Homeric audience would not think it odd that Patroklos had multiple dogs with him at Troy, but I think given what is in Homer, it is a big stretch to suggest they had anything to do with fighting.

Last, Herodotus (7.187) says that Xerxes brought lots of Indian hounds with him when he invaded Greece in 480. There is never any sort of explanation as to what role they performed.

Hopefully others can add some other references, because they are pretty obscure. I'd love to see at least one from a Late Roman source.