Kopecka A author Novotna T author Svobodova Z author Drabkova Z author text journal article 2024 This study describes a case of poisoning by pyrrolizidine alkaloids in a horse. To the best of the author's knowledge, this is the first confirmed case of Senecio ovatus poisoning. A six-year-old 450-kg Irish cob mare was presented to the Equine Clinic of the University of Veterinary Sciences Brno (Czechia) with symptoms of hepatic encephalopathy, which progressively worsened with time despite intensive therapy and led to euthanasia. A complex diagnostic and therapeutic approach including the post-mortem patoanatomical and histopathological examination is described here. Regarding the histopathology of the liver, there was necrosis with haemorrhage, fatty changes and inflammation. A later inspection of the grazing area revealed the presence of Senecio ovatus (wood ragwort). A sensitive chromatographic method was used to determine the pyrrolizidine alkaloids and their metabolites in the plasma and the liver. In both of the samples, metabolites of pyrrolizidine alkaloids were detected. Although pyrrolizidine alkaloid poisoning was proven, the histopathological findings typical for this disease were absent. It is clear from our case that the histopathology in cases of poisoning by pyrrolizidine alkaloids may not always be conclusive. equine; histopathology; chromatography; intoxication; pyrrolizidine alkaloid; wood ragwort 10.17221/37/2024-VETMED https://vetmed.agriculturejournals.cz/artkey/vet-202409-0003.php https://vetmed.agriculturejournals.cz/artkey/vet-202409-0003.php continuing 69 9 329 336 2024 03758427 periodical academic journal