Don't say someone has passed away or has gone to sleep, she suggests. Instead, explain that death means the body no longer is working.
Talk with your child about what happened, because a child's fantasies about the situation could be worse than what actually occurred.
"It's most important to let children know you love them and will continue to be there for them," McCullough says.
As children get older, they need a more complete explanation of what happens when a person or pet dies, says Dr. Robert Cody, co-owner of Cumberland Valley Veterinary Clinic in Hagerstown.
"They have to struggle with the realization that life is a temporary experience," he says.
Children feel an emptiness because their pet no longer is there, he says. Whether to get another pet depends on the individual, because the period of mourning varies.
Some people are so shocked that they won't even consider getting another pet, while others want one immediately, he says.
Obtaining another animal may be acceptable to young children, but teenagers may consider it an insult because they consider the deceased pet to be irreplaceable, Cody says.
All children grieve differently, and the process varies according to their age.
Children ages 2 to 6 think of death as temporary, reversible and something that happens to other people, McCullough says. They show a natural curiosity and view a dead person or animal as something broken that can be fixed.
"They'll see a dead bird, and they'll want to tap it and push it," she says.
Between the ages of 6 and 8 they begin to get a clearer picture of what has happened, and they often think they are responsible.
They may think "I told Johnny to drop dead, and today he's dead, so I must have caused it," McCullough says.
At about age 9, a child's understanding of death is similar to that of an adult, she says.
Children are the forgotten mourners, and they often aren't included in funeral arrangements, she says.
She believes children should choose whether to attend a funeral. If they want to go, tell them beforehand exactly what they'll see, and that you'll take them home when they are ready.
Let them express their feelings by writing a letter or poem to read at the memorial service, or by placing a special memento in the casket.
Children only can take grief in small portions, McCullough says.
"A lot of times they will grieve outwardly, then will run off playing," she says.
As a parent, it's natural to want to protect children from the hurts in life, McCullough says.
"If we shield children from death, we deny them the opportunity of going through the grieving process, and this increases their sense of isolation," she says.
They planted a tree in memory of their dog: how one family dealt with death.