[pawzaddict]

That is called resource guarding. There is a good sticky on it I will find for you

 

[pawzaddict]

http://www.dogforum.com/dog-behavior/resource-guarding-causes-prevention-modification-7511/

and welcome to the forum

 

[pawzaddict]

Pinning a dog, rolling a dog, doing whatever where the outcome is you scared the dog, is not good. Stick to positive reinforcement and it will work. Also ditto fawkese on working on drop its, leave its, give its, etc etc. But with you not the other dog