Two of April Manning’s children, Mac and Lilah, had just survived the mass shooting at the Covenant School in Nashville. They needed stability and time to grieve.

So she did everything she could to keep the family dog, Owen, their sweet but ailing 15-year-old golden retriever, with them for as long as possible. She pushed back his final trip to the vet, keeping him comfortable as he slowly moved around the house.

Getting another dog was the furthest thing from her mind. But a few weeks after the shooting, her children sat her down for an important presentation.

Prepared with a script and a PowerPoint — “Why We Should Get (Another) Dog” — they rattled through research showing the mental health benefits of having one. It could limit their chances of developing PTSD and help them feel safe. Playing together would get them outside and boost their happiness.

Ms. Manning and her husband considered. Maybe a second dog was possible.