Anemia is a well-known disorder in CKD dogs, but its frequency in AKI dogs has been poorly investigated. The aim of the present study was to retrospectively evaluate the frequency of anemia, its degree of severity, and regeneration rate in relation to IRIS grade, etiology, therapy, and out-come. Medical records of dogs (2017-2023) with historical, laboratory, and ultrasound findings consistent with AKI were retrospectively reviewed. According to etiology, AKI was classified as ischemic/inflammatory (IS), infectious INF), nephrotoxic (NEP), obstructive (OBS), and unknown (UK). AKI dogs were also classified according to therapeutical management (medical vs hemo-dialysis), survival to hospital discharge (survivors vs non-survivors). AKI dogs were considered anemic in case of HCT 38 g/dL). Regeneration rate was considered absent (RET< 60,000/μL), mild 61,000- 150,000/μL), and moderate (> 150,000/μL). A total of 120 AKI dogs were included the study, and anemia was found in 86/120 dogs (72%). The severity of anemia was mild in 32/86 dogs (37%), moderate in 40/86 dogs (47%), severe in 11/86 dogs (13%), and very severe in 3/86 (3%). Anemia was normo-chromic in 71/86 dogs (83%), hyperchromic in 12/86 dogs (14%), and hypochromic in 3/86 dogs (3%). Normocytic anemia was present in 56/86 dogs (65%), microcytic anemia in 27/86 dogs (31%), and macrocytic anemia in 3/86 dogs (4%). Non-regenerative anemia was found in 76/86 dogs (88%). The frequency of anemia increased significantly (p