dogs' some facial expressions
1.when a dog feel the danger its skin on the forehead and on the root of the ears will be tight.if it feels satisfied and happy,its forehead and ears will be slack.
2.when a dog shows its teeth,it will tighten its lips,this time,it will roar lowly to its rival usually.it would also tighten its lips when it yield to its rival,like people smiling.
3.when a dog feels relaxed,its tongue will stick out.the dog does it when it is panting or to radiate the heat that is in the body or feeling heavy pressure.