A dog presents with acute onset vomiting, hemorrhagic diarrhea and fever. On fecal examination, you find many large fluke eggs. You question the owner and discover that the dog was recently in Oregon on a boating trip. What agent is most likely causing the clinical signs in this dog? 一只狗由于急性呕吐，血便和发烧前来就诊。粪便检查是你发现了较大的吸虫卵。你询问主人后得知该犬最近去过俄勒冈船游。导致该犬出现这种临床症状的病原可能是什么？