Veteran Don Harvill leaned on alcohol and medication to cope with his PTSD, hoping that he could forget what happened in Iraq 12 years ago. He was drunk for two days after he returned from the war, where he felt some responsibility for the death of a fellow soldier. Harvill turned to a therapist for help, but he still couldn't move forward. This spring, more than a decade after he went in Iraq, his nightmares finally stopped. Harvill, 47, says a three-week intensive program at the Center for Veterans and Their Families at Rush University Medical Center helped ease years of persistent pain. But nothing helped more with his healing, he said, than an exuberant, golden Labrador and mastiff mix named Sierra. "She has changed my life," Harvill said of Sierra, who was given to him by K9s for Veterans and has been trained to help with the Wilsonville, Ill., vet's specific needs. Sierra senses his anxiety and stands protectively nearby, as Harvill talks about his deployments to Iraq and Afghanistan. "The big thing that I feel with her is there's a bond. When I left the military, you lose part of it. But now it's like I have it with her. She's got my back at all times." Michael Tellerino, CEO and founder of K9s for Veterans, said the organization travels to kill shelters, looking for animals with a calm and eager-to-learn temperament. It matches bloodhounds and Labradors, and even a Yorkie, to a veteran's lifestyle — city or town, apartment or home with a yard. K9s also ensures that veterans have a letter from a psychiatrist recommending the dog. The service is free to soldiers. People with PTSD tend to self-isolate, says psychologist Michael Brennan, associate clinical director for Rush's Road Home Program. He says having a dog means an owner must walk it outdoors. For a veteran like Harvill, who is nervous around crowds, the canine companion may make him feel more comfortable in public spaces. "Particularly combat vets, they have associated crowded places with danger," Brennan said. "In crowded places where a dog would go with them, then they're retraining and relearning that crowded places aren't necessarily dangerous." Veterans who attend the free intensive program are receiving therapy and taking part in fitness and stress reduction programs. They stay in the Illinois Medical District Guest House, near Rush. Of the 120 people who have graduated from the program since January 2016, 92 percent are post-9/11 veterans. Many veterans join the program years after their tours. It takes time to understand symptoms or acknowledge a need for help. "I think we have only begun to see what PTSD looks like from Iraq and Afghanistan," Brennan said. Harvill served seven years in the Navy before enlisting in the Illinois Army National Guard. In 2004, he deployed to Iraq with the Illinois Army National Guard's 1644th Transportation Company, helping to transport equipment. A trained mechanic, Harvill took pride in ensuring trucks were as equipped and safe as possible. He recalls how his team spent Christmas Day fixing a Humvee crippled by an explosive device. When one soldier felt unprotected on all sides while holding a gun on top of a truck, he added steel to one side. "Anything you wanted, I did," he said. On Feb. 9, 2005, Sgt. Jessica M. Housby was riding in a cargo truck when an improvised explosive device detonated near the convoy, according to an Illinois Army National Guard spokesperson. The 23-year-old Rock Island, Ill., native was killed. Housby's mother, Deborah Housby-Bundy, said her daughter was an outgoing person who got along with everyone she came in contact with. More than 1,000 people attended her funeral. "She was a very bubbly, I'm talking a very bubbly person," Housby-Bundy said. Her fellow soldiers didn't find out about her death until hours later, Harvill said, when they were told by superiors to head toward the chapel. Harvill said he knows he did everything he could to make the trucks safe. And a therapist helped him understand he should let the enemy, not himself, shoulder the blame. But the responsibility he felt shadowed him long after — through his 2008 deployment to Afghanistan, and even during times spent with his family. Night terrors started when Harvill returned from Iraq. His boss told him he had changed. He and his wife sought marriage counseling. At Rush, after years of avoiding talking about what he was experiencing, he found himself holding a stress ball and water bottle and telling a group his story. They were silent. But later, many shared the same feelings. His wife, Amy, recalls that when he met Sierra, it only took a few minutes before they were playing catch and rolling around on the floor. She watched, crying. She says her husband is a different man from the one who could barely get out of bed. Sierra has given him purpose. "It's keeping him occupied," she said. "He likes to have that responsibility of taking care of someone else. (He's) taking care of himself now too. "We've got an adorable little blonde at home that I don't have to worry about," she said. On a recent afternoon driving through stressful Chicago traffic, Sierra placed her nose on his shoulder the entire way. She sleeps between them at night, the back of her head nestled on Don's chest and her paws on Amy's back. Harvill wants other soldiers to know that there are many options available to help with healing. Before, he said, he didn't care if he lived or died. He barely talked to his adult daughter or son. "It's hard to explain, because I felt like a failure," he said, choking up. Now, his daughter jokes that he calls too often, bragging about what tricks Sierra has learned. "She's bringing me closer to my kids," he said, "because they can't wait to meet her."