Preferences

Seems to me that one tennis ball is pretty much the same as another. But, not to Darby.

The ball on the bottom is called a "Tuff Ball" and it is indeed tough.  A little harder, and little rougher than a "regular" tennis ball, like the one on top.

Darby has a decided preference for the Tuff Ball.  If I throw the regular ball, she will run after it, but more often than not, leave it lying there while she runs back to me.   If I throw the tuff ball and regular ball at the same time, she will sniff both of them and pick up the Tuff ball and bring it back. 

I wonder what she doesn't like about the regular ball--the feel? Or maybe the smell?  Maybe it smells like the veterinarian's office where we got it on Saturday when Darby also got a kennel cough shot--maybe it brings back a bad memory?