title: Mechanisms underlying Phalaris aquatica "sudden death" syndrome in sheep.
abstract: Twenty outbreaks of Phalaris aquatica "sudden death" syndrome in sheep were investigated between 1981 and 1991. Four were confirmed and one was suspected, to be a cardiac disorder; 5 were confirmed and 3 were suspected, to be a polioencephalomalacic disorder; the aetiology of the remaining 7 outbreaks could not be determined. Potentially toxic levels of hydrocyanic acid (20 to 36 mg/100 g) were measured in the 3 toxic phalaris pastures tested. The measurement of potentially toxic levels of nitrate nitrogen (2920 micrograms/g) in toxic phalaris pastures by others, was noted. It is suggested that phalaris "sudden death" syndrome could have as many as 4 different underlying mechanisms, and that these might reflect the presence in the plant of a cardio-respiratory toxin, a thiaminase and amine co-substate, cyanogenic compounds, and nitrate compounds.
authors.affiliation: New South Wales Agriculture, Agricultural Research and Veterinary Centre, Orange.
authors.forename: C A
authors.initials: CA
authors.lastname: Bourke
authors.forename: M J
authors.initials: MJ
authors.lastname: Carrigan
mesh_terms: D000818:Animals; D003645:Death, Sudden / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary; D004196:Disease Outbreaks / Q000662:veterinary*; D004678:Encephalomalacia / Q000453:epidemiology / Q000209:etiology / Q000401:mortality / Q000662:veterinary; D010939:Plant Poisoning / Q000453:epidemiology / Q000209:etiology / Q000401:mortality / Q000662:veterinary*; D015995:Prevalence; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000209:etiology* / Q000401:mortality; D013577:Syndrome