The objective of this retrospective study was the evaluation of the administration of a haemoglobin (Hb)-based oxygen carrying solution (Oxyglobin) to cats over a time period of 4 years. Indication, infusion volume/24h, number of Oxyglobin infusions/cat, Hb concentration pre- and post-infusion, adverse events, and patient outcome were evaluated. Forty-eight anaemic cats received 65 Oxyglobin infusions. Prior to administration of Oxyglobin, Hb concentration ranged from 2 to 7.8 g/dl (median 4.9 g/dl), the volume of Oxyglobin administered was 4.4-25 ml/kg/24h (median 9.8 ml/kg/24h). An increase of Hb was noted after 41 of 49 infusion events. Severe side effects were noted in seven cats with cardiac disease, which developed pulmonary oedema (five), pleural effusion (three), and respiratory distress (one). They received 6.7-19.8 ml/kg/24h (median 12.3 ml/kg/24h) of Oxyglobin. Four of these seven cats received whole blood transfusions on the same day; five cats died and one was euthanased. Overall 24-h survival rate was 77%. Administration of Oxyglobin efficiently increased the Hb concentration. However, in cats suffering from cardiac disease, there is a high risk of life-threatening circulatory overload at the doses used in this study.