Objectives To identify differential diagnoses for subconjunctival haemorrhage in dogs. Materials and Methods Retrospective case series. Results Of 147 dogs with subconjunctival haemorrhage, 119 had a history of trauma. The most common types of injury were vehicular trauma (47/119) and dog attacks (32/119). Confirmed or suspected non‐accidental injury was reported for 5/119. Of the 28 dogs without a history of trauma, 13 had a bleeding disorder and of these, immune‐mediated thrombocytopenia was the most common diagnosis (9/13). Other causes included seizure disorders (4/28), vasculitis (3/28) and ocular or periocular disease (3/28). Clinical Significance Subconjunctival haemorrhage in dogs can be secondary to a wide range of injuries and systemic diseases, bleeding diathesis or ocular disease.