From 噛(か)ませ (kamase, 連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 噛(か)ませる (kamaseru)., causative of 噛(か)む (kamu)) + 犬(いぬ) (inu, “dog”).
かませいぬ • (kamase-inu)