This study seeks to examine feasibility, acceptability, safety, and preliminary efficacy of Equine-Assisted Therapy for veterans with posttraumatic stress disorder (EAT-PTSD). While several well-studied, validated treatments for PTSD exist, some individuals find these treatments ill-suited, ineffective, or undesirable. EAT is an alternative therapy widely used by organizations, such as PATH International Equine Services, that endorse its effectiveness for treating a variety of mental health issues. These claims have drawn criticism because the published research contains glaring methodological flaws, making it difficult to assess how effective these therapies actually are (Anestis et al., 2014). Equine-assisted therapies present a unique treatment modality that might effectively treat PTSD, particularly for individuals who have difficulty with other treatment modalities. In EAT, a psychotherapist and equine specialist work together to help the patients negotiate interactions with a horse using structured interventions or activities.

In this pilot study the investigators will develop the EAT intervention and determine whether research methods (evaluation interviews, assessment measures, videotaping procedures) are acceptable to participants. Specifically, the investigators will focus on issues such as session length, appropriateness of the "content" for treatment of PTSD, ordering of session content, adherence to the manual of the equine therapeutic team (based on observations made during supervision and feedback from the consultants), and will detail logistics of data collection and how best to record the sessions (camera angles, etc.).

Inclusion Criteria:

• Between the ages of 18 and 70
• Current DSM-5 diagnosis of PTSD as determined by a) full criteria met on CAPS, and b) clinical assessment
• Able to give consent, fluent in English

Exclusion Criteria:

• History of psychiatric diagnosis of psychotic disorder, unstable bipolar disorder
• Elevated depression of clinical concern and/or score of >25 on the Hamilton Rating Scale for Depression
• At elevated risk for suicide based on history and current mental state
• History of substance/alcohol use disorder at severe level within the past six months, and current diagnosis of substance/alcohol use disorder at a moderate level within past two months
• Fear of horses or other large animals
• Orthopedic or other physical conditions and/or limitations that prevent people from walking unassisted and/or walking freely in the ring.

Study period (baseline to 3-month follow-up; total: five months)