A friend of mine brought up a pet dog.
His 8 year daughter daily played with the dog and used to treat it as her friend.
Recently, the dog died, and now the daughter of my friend daily asks about that dog, any ideas to comfort the daughter?
The tried and tested method that seems to have been the standard amongst all my friends when they were kids is that the pet has gone to a farm out in the country where they have a great time chasing animals etc.
This is all very well, and simple when the child is young, but once they get up to 7 or 8, I am of the opinion that it is better to start being honest and discuss life, especially if they have elderly grandparents - coming to terms with the loss of a pet can help them prepare emotionally for the loss of a family member.
@oɔɯǝɹ's comment about something to remember the pet by, such as a picture has great value here: the message to the child being that although things change and pets don't last forever, you can remember them and still carry on with life...possibly even getting another pet.
Just let the child go through the process of losing a pet. It is also a journey for her to cope up with the situation. Encourage her to talk about her pet, because sharing will help her to cope up. Your friend can also bring her daughter out, like dine-in in her favorite restaurant and or go some out-of-the-town trips, so she can have a change of environment and experience new things. In time, her daughter will accept it, as long as she goes through the process.
Rory's answer is a wonderful one in its acknowledgement of different age levels and that coming to terms with the death of a pet can actually help later with other deaths that will eventually be encountered, but I disagree with the beginning premise that it is ever okay to lie about it. A child will figure out your lie eventually and they can feel the pain of the loss all over again when they figure it out later - meaning you are only delaying the inevitable anyway.
With the youngest kids (younger than the eight years in question) it is super important to remember they will be very literal about what you say so be careful. Statements like, "It is like he is sleeping but won't wake up," can actually create a fear of falling asleep. Something more like, "you know how sometimes things stop working? Well that can happen to animals too. Your dog's body stopped working" Then you would fill in what you believe happens if that is helpful info like, "now he is in doggie heaven." can be comforting for believers.
Books can be helpful in presenting ideas about death to kids in ways they can understand. The book chosen will depend upon your beliefs in life after death, but there are plenty of options out there to help the conversation along, but you can also be a little more creative about it too. We actually used Eric Carle's A House for Hermit Crab when a beloved uncle that believed in something akin to reincarnation died. I discussed the death with her as an analogy where when the hermit crab gets his new shell he has "gone on" to the next life. I told her what we believed and what he believed about what the next life was like (She was four).
Lastly, have a ceremony of some sort. Make it a "memory party" and talk about some funny stories about things the dog did. Discuss qualities about the dog that will be missed. Let her cry about it a little bit and say good-bye to her dog. Maybe reenacting one of her favorite activities with the dog one last time to honor his memory? This will help her honor the memories and let go. If you let her offer up the ideas about what activity should be included, it will work for her in terms of simplicity/complexity and letting go.