When a family pet dies, naturally the humans in the household grieve the death of their beloved companion. However, surviving animals in multipet households may also react to the loss in a variety of ways.

In her book "How Animals Grieve," Barbara J. King, a professor of anthropology at the College of William & Mary, cites studies and observations that show that animals in the wild, from elephants to birds, exhibit grieving behaviors, as do household pets.

She defines grief as:

"When a survivor animal acts in ways that are visibly distressed or altered from the usual routine in the aftermath of the death of a companion animal who had mattered emotionally to him or her."

The Companion Animal Mourning Project, a study conducted by the American Society for the Prevention of Cruelty to Animals, found that more than 60 percent of dogs and cats exhibited four or more behavioral changes after the death of a fellow pet in the household. Changes include eating less or possibly not at all, craving more attention from their owners, changes in vocalization (barking or meowing more or less than usual) and changes in sleeping places or other habits.

"Most of the behaviors fall under the category of distress reactions," said Katherine Pankratz, clinical behavioral medicine resident and American College of Veterinary Behaviorists resident at the North Carolina State University College of Veterinary Medicine. "It can be because of the loss of their companion or the change in routine or the owners' reactions."

Companion animals are attuned to owners' moods, so they can pick up on the sadness the humans are experiencing. The death can also cause a break in the social structure among the pets.

Pankratz said dogs often have relationships with each other that can be disrupted by a death.

"If the lead animal, a pet that initiated meals or activities, is lost, the surviving pet may show signs of distress such as decreased appetite, because they have lost the leader to those activities and are now adjusting to a new routine without the leader pet," she said.

Cross-species mourning

The reactions can occur even if the pets are from different species, said Molly Stone, a pet behavior specialist.

"Their social experience is small compared to ours, and their time is spent with the other pets in the home while we're at work," she said. "Should that companion suddenly be gone, it should have an effect on the whole household. Cats mourn when it's the loss of a dog, dogs when it's a cat. I'm not sure it makes a difference what species."

The keys for owners are in understanding their pets and giving them time to adjust to the new situation. Pankratz said it may take a month to six months for grieving pets to adjust. She advised that owners monitor behaviors and consult a veterinarian if the behaviors become prolonged or extreme, particularly if the pet stops eating for a length of time.

Owners should resist the temptation to console their pets by giving extra treats or other special food because the pet will continue to expect those extra calories later. She similarly cautions against offering too much extra attention, again establishing a pattern that pets might expect owners to continue.

New routines can help

For pets that seem anxious, exercise can often help. Establishing a routine also is a good idea.

"Try to develop that new routine," Pankratz said. "For pets, consistency and predictability is really important. The previous routine can no longer continue, so developing a new routine can help them be less anxious."

Depending on the pet, offering some distractions may help, Stone said.

"You could provide some species-specific distractions, such as extra trips to the dog park, new chew toys," she said. "Maybe walking in a different area can distract them, give them something else to think about and cause their brains to start making happy hormones."

And, the experts say, don't get a new pet solely out of a desire to help the surviving pet.