Integumentary fibrosarcoma in a free‐living swan ( <i>Cygnus olor</i> ): Medical and welfare considerations

Abstract A 10‐kg adult male mute swan ( Cygnus olor ) of unknown age was admitted for investigations of two large ventral masses overlying the keel bone, which were discharging purulent material. The masses measured 8.9 × 2.1 cm and 4.2 × 3.2 cm. Empirical treatment with non‐steroidal anti‐inflammatory drugs and antimicrobials was instigated. The masses continued growing, and the patient lost 1.4 kg in 21 days. Haematology and biochemistry denoted leukopenia and heterophilia, consistent with systemic inflammation. Core biopsies and culture and sensitivity were taken under general anaesthetic, revealing fibrosarcoma and a mixed population of Staphylococcus sciuri and Acinetobacter baumannii , with oxacillin resistance. Euthanasia was chosen in the swan's best interests. Integumentary neoplasia is common in pet birds; however, this is the first report in a swan. Practitioners must remain cognizant of ethical implications of releasing a free‐ranging animal with neoplasia and for protracted hospitalisation. Biopsy, when safe and practicable, can be utilised.