Meaning of “Innu(イッヌ)”

“Innu(イッヌ)” means dog, it’s from “Inu(イヌ)” which means dog.
“Innu(イッヌ)” is just a slightly humorous modification of “Inu(イヌ)”. This modification style is maybe from “Icchi(イッチ)“, I think.
This is an internet slang, and we can often find this word on X.

Example Conversation on X

Someone’s post ： A Innu(イッヌ) relaxing like an old man [ photo or movie ] Someone’s reply：So Cute!!!

誰かの投稿： おっさんみたいにくつろぐイッヌ [ photo or movie ] 誰かの返信：かわいい！！