You may have seen the YouTube video of a cat trying to revive another cat who’d just been hit and killed by a car. For pet owners, it’s sad and touching, and it raises questions in our minds: Do our pets understand what’s happening when another pet dies? Do they feel grief?

To both questions, professionals say sometimes yes, sometimes no.

Dr. M. Duffy Jones, an Atlanta vet, says, “They have a strong instinct for individual survival and sometimes that will carry over to other pets or people.” Dr. Jones has seen pets that seem to understand an animal companion has died, and others that don’t understand — or don’t care.

Chris Hamer, a dog behavior consultant, shares a story of death among her own pets:

“We recently were faced with the death of our 17 year old lab. I feel that my other dogs knew that Ember was close to dying . . . I watched the other dogs closely for signs of grief. The human family members were certainly grieving but other than curiosity about Ember’s blanket that she went to the vet on, they didn’t display any unusual behavior.”

She has, however, had clients report grieving in their pets (though this may be a projection of the owner’s feelings onto the animal). Dr. Jones also reports that some animals seem deeply affected by the death of a companion, to the point of getting physically sick — but says this may be a reaction to the owner’s stress and any change in routine. Dogs especially, as we’ve seen before, are very sensitive to the moods of humans. They’ll feel better if the family sticks to its usual schedule as much as possible, though maybe with a little extra playtime for the surviving pet.

So you’ll have to play it by ear if you find yourself and your pets in this situation.