TICK-BORNE DISEASES AS A CAUSE OF POST-OPERATIVEFEVER AFTER COLIC SURGERY IN NORTHERN ITALY

Background: Fever can be a common complication after colic surgery and definition of its cause is paramount to avoid antibiotics overuse. Tick-borne diseases are endemic in northern Italy and a common cause of pyrexia and hyperbilirubinaemia. Objectives: To evaluate the incidence of post-operative fever caused by piroplasmosis in horses recovered from colic surgery. Methods: Records of horses that recovered from anaesthesia after emergency laparotomy between January 2018 and March 2021 were considered. Blood samples were collected in the first postoperative day and tested by PCR for Babesia spp., Theileria spp. and Anaplasma phagocytophilum. Clinical and haematological signs of anaemia, fever and icterus were recorded, as well as post-operative antimicrobials administration. Results: 139 horses met the criteria for the study. Overall 82/139 horses developed post-operative fever (59%). The majority (38/82, 46%) developed pyrexia at a median of 4 days (3–5) post-operatively, while 35/82 (43%) tested positive by Babesia/Theileria PCR and had other symptoms, in addition to fever, associated with piroplasmosis. Sequencing of PCR positive samples revealed the presence of T. equi, B. capreoli, B. motasi, and A. phagocytophylum. In 8/32 (25%) cases, an incisional discharge was present. Horses were treated with a 5–7 day course of EV oxytetracycline. Resolution of symptoms occurred in 30/35 cases. In the remaining 5 cases (1 positive to A. phagocytophilum, 3 to Babesia, 1 to T. equi), administration of imidocarb was necessary. Conclusions: Delayed onset of postoperative pyrexia may be due to piroplasmids infection in endemic areas. Oxytetracycline administration is effective in resolving the symptoms in the majority of cases.