Topic: What do the icons mean on Nintendogs + Cats?

Whenever you rub your dogs head, feed him, or teach him a trick, you see a little icon pop up. What do they mean? For example, when you rub your dog's head, you see yellow or purple sparks, when you give him a treat, you see some clovers, or when you feed him, you see blue plus signs. Do these have meanings, or are they just there. Please help me!

I think it means you earned owner points, but I never noticed they were different symbols.

hm... Ive seen different colors like purple, yellow, green, and blue and each symbol has its own color.