In the Lenormand oracle cards the mice or rats called by some is usually not a welcome card especially if it is near the heart card, ring card, fish card or right beside the Gentleman (male significator) and the Lady (female significator.
The connotation is usually theft or loss, a slow eating away at something.
Beside the heart card= a slow deterioration of emotional/sentimental feelings
Beside the ring card= a gradual release of commitment or agreement
Beside the fish card= more money goes out than comes in. In some cases it can actually mean being swindled.
When beside either of the 2 significator cards- you can bet something is “eating” away at the person. If the tree card is in close proximity then there could be an illness or disease of a debilitating sort.