Sphaeridiotrema flukes, the cause of ulcerative enteritis in a Cygnet Cygnus olor).
D000818:Animals; D001715:Bird Diseases / Q000209:etiology / Q000473:pathology*; D001717:Birds; D004751:Enteritis / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D005260:Female; D014200:Trematoda; D014201:Trematode Infections / Q000473:pathology / Q000662:veterinary*