Is there another reference that mentions Garm in the Eddas? When I read these, I look for repetitions in character references. There is a lot of artistic liberty in the Eddas. Language forensics and patterns are about all we have to sort out what is myth, legend and artistic liberty.
I looked last night and I all I found was that particular reference. A few references to a guardian dog in Hel's realm. Some sources do use this reference to indicate Fenris.
I looked also. The best reference I could find as to Garm being described as a hound was in Grimnismol stanza 44. I will paste it here so you can see it.
44. The best of trees must Yggdrasil be,
Skithblathnir best of boats;
Of all the gods, is Othin the greatest,
And Sleipnir the best of steeds;
Bifrost of bridges, Bragi of skalds,
Hobrok of hawks, and Garm of hounds.
I cannot find any other reference other than what Snorri writes for us.
No one wanted to touch on this stanza, I am surprised. Perhaps I incorrectly noted it numerically. She I checked the academic sourcebooks it was listed as stanza 66 in the Voluspa.
Nithhogg, a dragon like creature is depicted gnawing in the roots of Yggdrasil, the world tree. There is little about him in the Eddas yet he is said in legend to try to rise during the struggle on Ragnarok. Neither created by the Gods nor mentioned to be a part of the worlds when there was only fire and ice, the real question is what is he and what is his purpose? Is he the embodiment of evil in a system that does not acknowledge that duality? Or is he something that we just accept as being because artists depict him as there?
As this is a post about the Eddas, I would like to ask do you feel the Eddas are the basis of Norse belief or are they merely a set of works to help us understand a point in our ancestors history?
They definitely illustrate the mindset of our ancestors at a particular point in history. They illustrate a set of mores and values for daily living and give us an idea how our deities are connected to us. It would be irresponsible to take every word verbatim. The eddas are single sourced out of Iceland and most likely written from Christian scholars. One has to assume some influence and some author derived poetic license. They are very useful in understanding the structure of the pantheon and to correlate which deities are connected with different aspects of the faith.
Think of the eddas as something that embellishes and enriches a faith that has a long tradition. It is not the source but rather a useful part of something much larger.