Case Description- One horse was examined and treated for moderate to severe abdominal pain. Clinical Findings- The patient was diagnosed with a diaphragmatic hernia after thoracic ultrasonography revealed several loops of small intestine located in the thorax. Treatment and Outcome- Conservative medical management of the hernia was attempted. The patient was discharged with instructions to continue slow re-feeding with small, frequent meals of a complete pelleted feed and grass. Shortly after leaving the hospital, the horse experienced another bout of severe colic and was euthanized. Clinical Relevance- Horses with diaphragmatic hernias most commonly present with signs of colic, although dyspnea due to pulmonary compression may also occur. This type of hernia can be acquired or congenital. An accurate diagnosis of diaphragmatic hernia requires a thorough history, physical examination, and additional imaging. In symptomatic patients, a well planned surgery is recommended and numerous surgical techniques have been attempted.