Why are cats so much harder to do?

I spent two days working on this portrait of a cat....I'll set it aside for now and work on the other one I have to do. Dogs seem so much easier to do.
Maybe its the size that makes a difference. This one is 5"x 7" while the dogs I did below were 8"x 10". Harder to get the detail in small paintings.
This is the painting obviously....the colors are actually a little darker than they show here.
Here's the original photograph I worked from.