The persistence of chronic post-traumatic stress disorder (PTSD) among veterans of the Vietnam War warrants an exploration of new treatment approaches, such as equine-facilitated psychotherapy (EFP). The purpose of this study was to use open-ended interviews to explore five Vietnam veterans’ perceptions of their bond with an equine partner during EFP and how it influences their behavior and PTSD symptoms. Questions addressed their relationships with their equine partners, including its development and impact on their interpersonal relationships. Attachment Theory provided a framework for understanding the four main themes that emerged from analysis of the responses: positive changes in thoughts and behaviors, veterans’ beliefs about horses’ cognitions and emotions, emotions and emotional regulation, and interpersonal and interspecies relationships. The authors concluded that EFP may support personal growth and healing because horses serve as attachment figures, provide a secure base for emotional exploration, and encourage non-verbal communication.