Maltese Shiatsu female dog growls when plays with another dog. Why?

Why? dose my mum's dog 1 half years old Maltese Shitzu female dog growls when she plays with the Kelpie x 1 year old female. And before she had a Rottweiler. But my mum's boyfriend split up with my mum and the boyfriend took the Rottweiler with him, the Rottweiler was a she about 4 years old. The Maltese Shitzu always growled when played with the Rottweiler as well. It this normal or dose she not like the other dog?

Yes my shih-zu and my rottie growl all da time at eachother....

I have 2 dogs that growl when theya re playing. it is normal. it is their way of talking to each other. their growls will change into a more serious sound if eithe r of them is getting mean.

Just sounds like excitement. My Shih Tzu growls all the time, just her way of 'talking to you'.If she is not hostile and/or snappy then i wouldnt worry at all.

all it is is a dog having a little fun not nad at all