This is so adorable! I especially love how the mouse is freaking out half to death while the cat just stares happily at it!
The fur detail you've implied on the tail looks outstanding and how this same detail followed up on the belly, head, and in the ears looks amazing! I eyes as usual look beautiful and the realism comes from that lighting effect on the eyes where your light source isn't just some ball but you can see the detail to the shape of the light source and that's what makes them look so amazing.
The colors look wonderful on this character and how you shade the character looks so believable in terms of how a shadow would look like. There aren't any sharp edges and everything is smoothed out to look more realistic and it really shows on this character!
Amazing work and again, love the expressions you use in your drawings, amazing!