AbstractBackgroundAbomasitis is a syndrome affecting young milk‐fed calves. The current veterinary literature describes mainly its necropsy findings.ObjectivesTo describe the clinical presentation, complementary tests, treatments, and case‐fatality rate of calves with a clinical diagnosis of abomasitis and to identify potential factors associated with outcome.MethodsObservational retrospective cohort study (2006‐2016). Review of the medical records of calves <3 months of age presented with abdominal and abomasal distension for <7 days that were clinically diagnosed with abomasitis at the Faculty of Veterinary Medicine of the Université de Montréal. A follow‐up examination was conducted by telephone interview.AnimalsTwenty‐three calves clinically diagnosed with abomasitis.ResultsMedian age of presentation was 3 days (range, 0‐62 days). The typical duration of the clinical course was <24 hours (15/23). On admission, the 2 most common clinical signs were anorexia (13/14) and positive succussion (13/14). Hyper‐l‐lactatemia (15/16) and increased γ‐glutamyl‐transferase activity (13/14) were the most common laboratory abnormalities. Hypoproteinemia (19/22) and a left shift (15/18) of the neutrophils also were observed. The short‐term case‐fatality rate was 52% (12/23). The clinical diagnosis was confirmed on all necropsied calves. Clostridium spp. and Escherichia coli were the most frequently isolated bacteria. Based on univariate statistical analysis, the surviving calves were significantly (P < .05) less hypothermic, less acidemic, less hyper‐l‐lactatemic, and had lower serum creatinine concentrations on admission than did the deceased calves.Conclusions and Clinical ImportanceIn our study, abomasitis was associated with a guarded prognosis.