To present a case series of horses diagnosed with diaphragmatic hernia, and to determine the significance of (1) historical information, examination findings, and laboratory data; and (2) exploratory laparotomy or necropsy findings on short- and long-term outcome. University Referral Hospital. Retrospective study. Forty-four horses/foals admitted between 1986 and 2006 with a diagnosis of diaphragmatic hernia made either at exploratory laparotomy or necropsy. None. Information from the medical records included history, clinical examination findings at presentation, and findings of exploratory laparotomy or necropsy. Logistic regression or the Fisher exact test was used to determine factors associated with survival. Outcome was defined as survival to discharge (short-term survival), and long...