It is true. What we perceive as happiness is short and our attachment to it make us suffer when we die and being reborn in a situation that is scary. I also remember reading about Shariputra's explanation in the Lamrim.
One day Shariputra went for alms, and as he was looking through the door to the family inside the house, he saw the son, his wife carrying a child on her lap, and they were eating a fish, giving bones to the dog and beating the dog. He saw all the changes in those relationships. The father of the son used to catch fish from the pond behind the house. So when the father died he was born as a fish in the water pond behind the house. The mother was attached to the house, so when she died she was reborn as the dog of the family. And the son’s enemy was attached to the son’s wife, so he was born as their child. The fish they were eating was their father. Shariputra, seeing all this, said, “Eating the father’s flesh, beating the mother, because that dog is the son’s mother. Carrying the enemy who was born to them on the lap. I laugh at the samsaric existence!”
In the history book of the thirty-three Zen masters, there is a story about one of the Zen master who went out for alms, passing by a rich man’s house. The rich man was out, but inside came running out a dog that barked at him loudly. The Zen master looked at it and reproved ,
" How dare you barking at me, because of the attachment of wealth that you came back as a dog, shame on you!" After having heard the master’s reprimand, the dog became sad and refused to eat. Lately, the rich man came back and realized that his beloved dog refused to eat, he asked his servants the reason. The servants told him that in the morning, there was a Zen master who passed by and said something to the dog and afterwards it refused to eat. The rich man was so upset that he went out to look for the Zen master. He queried , " What did you say to my dog this morning that has made him sad and refused to eat ?" The master replied ," Please do not get angry at me. The dog is your father." The rich man got even angrier and asked , " Why is that dog my father ?" The master said , " If you do not believe me, go home and see if the dog is lying under your father’s bed. Right where the dog is lying, you dig up and will find a bowl of gold. When your father passed away, he did not get a chance to tell you the secret; so he came back as your dog to guard it. Just go home and dig up then you will understand." The rich man immediately went back home, dug up under his father’s bed and found the bowl of gold. Afterwards, he ran back to the master and asked the master to help his father. The master convinced the rich man to use that gold for charity work. The rich man obeyed the master and few days later the dog died.