The train's conductor, who couldn't slow the freight train in time, initially thought he had struck and killed the woman, named Christine Spain, and her dog, but when he surveyed the scene, he saw that Spain had been dragged to the side, while Lilly had sustained severe injuries as a result of the collision. The pit bull's right front leg was de-gloved, meaning all of the skin and muscle had been removed, and X-Rays would later show she had sustained multiple fractures in her pelvis.
When Spain's son, police officer David Lanteigne, arrived on site, he helped tend to Lilly, and later stayed by her side as she was transported to Boston's Angell Animal Medical Center, where she is now in recovery.
"The first thing I saw [when I got there] was Lilly laying in the back of the car with her head up, alert, just looking at me, with her big amazing eyes she has," Lanteigne tells PEOPLE. "She never broke eye contact with me, her tail started wagging, and she knew I was there to help her and that she was going to be okay."
Upon her arrival at Angell, veterinarians made the decision to amputate her right front leg, and also placed steel plates in her left hind leg for support. A second surgery was later performed to address the fractures in her pelvis, but despite the severity of Lilly's injuries, doctors expect her to be able to walk again in a few months through physical therapy.
"It's going to be a long rehabilitation process, it's going to be expensive, but her quality of life will be there," Lanteigne says. "She has been so strong throughout this entire thing. When she's not all medicated up, you can see her personality shining through."
That personality is part of why Lanteigne was drawn to Lilly in the first place, when he adopted her as a gift for his mother from Animal Rescue League Boston three years ago.
"At first, she was nervous, she had some pretty bad scars on her," he says of their first meeting. "But she let down her guard. She was so trusting in me. She's everything truly that a pit bull is all about. It was right then and there I knew I had to get her."
For the time being, Lilly remains at Angell and is working on standing and stretching her muscles, but she is expected to be released within a few days, when she'll join Lanteigne, his girlfriend and their two golden retrievers at home. Because of her bravery, Spain suffered no major injuries in the accident.
"This was the most difficult time in my entire life," Langteigne says. "We're supposed to be strong for her, to help her through this, and Lilly's been the one who's helped us through this by her incredible strength. It's truly amazing."