In the Zoroastrian religion, a dog steps up to perform an important part of a deceased person's leavetaking of the world. The ritual is called sagdid, meaning "dog-sight," and the dog must be what is called "four-eyed," meaning it has two eye-like spots above its own eyes.
This ritual meant a great deal in the days before doctors could without doubt confirm a death. If the dog looked at the person carefully, they were still alive; if the dog would not look, the person was indeed gone. This was repeated several times, so the dog had more than one opportunity to check, and there was also one final sagdid as the deceased was placed in their tower of silence - the Zoroastrian method of sky burial.
The page I'm referencing for this mentions that the dog is brought in at a particular point in prayers, Yasna 31.4, which if I've made the correct conclusion is this verse:
4. If Asha is to be invoked and Mazda and the other Ahuras and Ashi and Armaiti, do thou seek for me, O Vohu Manah, the mighty Dominion, by the increase of which we might vanquish the Lie.
Just because I always like to give the fullest picture possible, though I do know I must be missing a number of fine points.
The section on sagdid here. Yasnas 28-34 in English here.