A search turned up:

https://www.dailymail.co.uk/sciencetech/article-3282530/Forget-sweet-treats-cats-BITTER-tooth-Felines-seven-taste-receptors-help-alert-poisonous-prey.html

https://www.urbandictionary.com/define.php?term=bitter%20tooth

Most likely, it means something like "sharp," "violent," or "dangerous." This could refer to a lion hide with the head and teeth intact, perhaps as a symbol of office -- or a live lion trained as a temple guardian.

Another possibility is that it was given as a divine symbol, because the lion is associated with Inanna.