yes. in fact mountain gorillas can not be kept in zoos because they miss their families so much that they become depressed and in some cases it was so serious that it lead to death. thats why you only ever see low land gorillas in zoos.
I believe its possible, I remember when one of my 3 dogs died all the others where really sad looking, they wouldn't be as happy, and would always stay near me. So yes i believe they do!.......yes they are over it now!!
YES. We had two dogs and one died, the other one became very depressed and wouldn't eat. Even though we weren't ready to get another dog, we did to try to help our dog. It worked, he has something else to think about then where his friend went.
Yes they can. My little male Chi is always so stressed I had to finally ask his vet for some medication for him. I haven't given him any yet. He will go through periods of depression and won't get out of his bed. We adopted him at age16 weeks along with his sister. They have never been apart. She is a brave little gal and you can tell she tries to care for him when he gets depressed. So yeah our little 4 leggers get depressed. We just have to love them anyway and encourage them. He's healthy just depressed and neurotic sometimes.
Technically, not at all, but they can get sad enough to get taxidermic from not enough attention if they are an only dog or another dog in the household dies. Same goes for a person or other animal that dies and the dog is close to that animal.