Idunn's Hound is a food item that most likely has less effective healing properties than Idunn's Apple.
In the English release of the manhwa, this item is misspelled as Idun's Hound.
After Sessy and Reina were wounded by Julianna, Lidia looks through her pack to find something to heal them with. As she only had one Idunn's Apple, she gave that to Reina while Sessy received the much cheaper Idunn's Hound. It made its debut appearance in Volume 10.
While Idunn's Hound does make an appearance in Ragnarok Online, it is known as either Pet Food or Monster's Feed, both of which share the same in-game graphic and concept art.