From Tolkien Gateway
Inclusion of material from Canto VIII[edit source]
There's some interesting material in Canto VIII about Huan that I think we could include, especially the part (emphasis mine) that he followed Celegorm into battle and "often" saved him.
...Hounds untold baying in woods beyond the West of race immortal he possessed: grey and limber, black and strong, white with silken coats and long, brown and brindled, swift and true as arrow from a bow of yew; their voices like the deeptoned bells that ring in Valmar's citadels, their eyes like living jewels, their teeth like ruel-bone. As sword from sheath they flashed and fled from leash to scent for Tavros’ joy and merriment. In Tavros’ friths and pastures green had Huan once a young whelp been. He grew the swiftest of the swift, and Oromë gave him as a gift to Celegorm, who loved to follow the great God's horn o'er hill and hollow. Alone of hounds of the Land of Light, when sons of Fëanor took to flight and came into the North, he stayed beside his master. Every raid and every foray wild he shared, and into mortal battle dared. Often he saved his Gnomish lord from Orc and wolf and leaping sword. A wolf-hound, tireless, grey and fierce he grew; his gleaming eyes would pierce all shadows and all mist, the scent moons old he found through fen and bent, through rustling leaves and dusty sand; all paths of wide Beleriand he knew. But wolves, he loved them best; he loved to find their throats and wrest their snarling lives and evil breath. The packs of Thû him feared as Death. No wizardry, nor spell, nor dart, no fang, nor venom devil's art could brew had harmed him; for his weird was woven. Yet he little feared that fate decreed and known to all: before the mightiest he should fall, before the mightiest wolf alone that ever was whelped in cave of stone.