The eyes will be much cuter if you do a big, dark pupil and bright highlights.
The bigness of the eyes is perfect and looks like a puppy should look like :3

Well, I'm not good in explaining English, so I edited your pic as i thought it might be nice.

http://i651.photobucket.com/albums/.....1257967651.jpg
I hope it was okay to edit your pic, I will take it down when you saw it :3 *just wants to help*

I just added a dark pupil and the highlights. With bright highlights the eyes looks more lively.. the eye is wet and reflects much light.. you are able to give your pup' much more emotions with that..
Just try it out and you will see the results :3

Your art is very nice though, I like how you colour without Outlines.. it looks very real.. :3 Don't be too shy to add some more highlights on other places too like the nose and the fur..

Rotties are very cute dogs btw.. love them <3

I wanted to thank you! I have a real hard time with eyes, because well they are tricky things to do. I am going to use that example as reference and maybe in some later pieces you will see much improvement. I appreciate it!

I'm glad if I had been able to help you! ^3^
I'm already watching you and looking forward to see the improvement :3