Grrrr with Grandma

Callie LOVES playing grrrr.  When she was a puppy, she never made a sound.  We never heard her bark, barley even a whimper.  But, when we played tug of war, she would imitate the sounds we made...which happened to be grrr.  She still loves to grrrr, but she did learn how to bark.  I think it was because her throat hurt that she wasn't able to bark as a puppy