Entre Chien et Loup
It is a phrase that appeared in France in the thirteenth century, "quand l’homme ne peut distinguer le chien du loup" The phrase is talking about when one can not distinguish well the differences between a wolf and a dog.
The lines in the tongue of blue dog ,probably, also draw teeth, more aggressive, making it a wolf.
LA LVNE, on the cover of darkness, often does not let us see things clearly, a friend easily mistaken for an enemy.
As you are readers of cards, I do not think it takes to translate this message.
I remember Kwaw mentioned somewhere the expresion entre chien et loup regarding this card LA LVNE.
À la tombée du jour, le temps entre le jour et la nuit, quand il en est ainsi tombée de la nuit on ne peut pas distinguer un chien d'un loup.
At dusk, the time between day and night, when it is so dark you can not distinguish a dog from a wolf.