Friend's Dog

Yesterday, my friend's dog died. I was very sad when she told me this news! I can't believe that this really had happened! We cried all day. We will neither get to see the dog again nor hold her, and we can no longer kiss her! She really was a well behaved dog who was very obedient.  When she was sick, she never did quarrel. So we did not know that she had an illness which caused her sudden death yesterday! Yesterday afternoon, my friend and I buried the dog; and we buried her at a place close to home.  She went to heaven, and now she's a little angel. Our little angel will be more happy, there will never be any more pain. We are happy for the little angel! 
The death of my friend's dog makes me very sad. I like dogs, and I really liked my friend's dog. But because of what happened yesterday, I could never keep a dog and I have been afraid of raising a dog, because I'm afraid one day my dog suddenly will be away from me, and I would be very sad.

My friend's dog

Yesterday,my friend's dog died.I was very sad when she told me about it!I can't believe it,but it really happened! We cried that day.We will never see the dog, hold her,kiss her ever again.She was a really well behaved dog and was very obedient, even when she was sick.That is why we couldn't even know she wasn't feeling well.This is what caused her sudden death yesterday.In the afternoon,  my friend and I buried the dog, somewhere close to her home.I'm sure our little angel went in heaven.She will be more happy and never suffer from pain anymore. We are happy for the little angel!
The death of my friend's dog made me very sad. I really like dogs. But because of what happened yesterday, I'm scared to raise one. so I can not keep the dog, I was afraid of raising a dog, This is because I'm afraid that one day i might lose him. I will then be very sad.

Note: Now theres a lot of different of ways to express the above. This is just one of them. There are certainly other good answers too. :)