For this wiki trail, I began at the article on the "Church Grim", since I was researching mythological canines to determine which one I wanted to pull traits from for one of my characters.
Church Grims are guardian spirits of churchyards, which would protect the church and the graves there from being robbed, defiled or having sacrilege committed against them. The Church Grim would typically take the form of a large black dog. It was commonly believed that the first one buried in a churchyard would be responsible for guarding it, and so a black dog was often buried first to take on that duty instead of a human soul.
From there, I found a link to "Dogs in Religion", which covered a variety of religious beliefs, including Judaism, Zoroastrianism, Islam and Hinduism.
The article basically covered some of the more prolific dogs in religions, or aspects of the religions that praised and/or honored dogs, though some of the religions highlighted actually looked down on dogs or viewed them in a negative light. Overall, it seems that dogs have a variety of meanings in various religions, sometime symbolizing good things, sometimes bad.
At the bottom of the page, I found a link to "Inugami", which intrigued me as I'd not heard the term before but could recognize it as Japanese.
Inugami are cases of spiritual possession by the spirit of a dog. The source of the spiritual possession varies based on various legends and pieces of folklore, as does how it affects the person. In some of the stories, it seems to be a source of power for the person possessed, whereas in others it seems to appear as a curse. The source of the spirit typically involves the death of a starving dog, though the method in which it was killed and the circumstances around it varied significantly.
From that article, I found a link to an article on "Raijū", which intrigued me since I'd seen Raijū in other media before.
Raijū are creatures composed of lightning that typically take the form of a white and blue wolf or dog. They accompany Raijin, the Shinto god of lightning, and are commonly attributed as the source of lightning strikes and phenomena.