Summer of the Wolves by Lisa Williams Kline

Headline: Stepsisters, yes. Friends? Maybe … Diana loves horses. Horses terrify Stephanie. Diana takes pills for her mood disorder. Stephanie smiles a little too wide. Now their blended family is vacationing for the first time since the wedding—at a ranch that only highlights the girls' extreme differences. Things seem hopeless, until Diana discovers caged wolf-dogs and convinces Stephanie to help free them. Though a truce is formed, a herd of unforeseen consequences is soon galloping out of their control. But it might be just what their relationship needs.