Amaranthus species

Abstract

MECHANISM OF ACTION: In the rumen nitrate is reduced to nitrite and following absorption haemoglobin is oxidised to methaemoglobin.TOXICITY: • Great variations both inter- and intraspecies • Nitrate - c. 0,5 g/kg sheep - 5g/kg cattle • Nitrite - c. 20 mg/kg sheep - 100mg/kg cattle For soluble oxalate poisoning, go to Urogenital Menu.SYNDROMES: Nitrate/nitrite poisoning.SYSTEMS AFFECTED: Haemopoietic system.CLINICAL SIGNS: Acute poisoning: Respiratory System: • Hyperpnoea • Dyspnoea • Anoxia precipitated by exercise Central Nervous System: • Ataxia • Tremors • Weakness • Terminal convulsions (brain anoxia) Cardiovascular System: • Cardiovascular failure, syncope • Cyanosis • Methaemoglobinaemia: Blood & mucous membranes a dirty chocolate brown colour • Rapid weak pulse (drop in blood pressure) Gastrointestinal Tract: • Diarrhoea • Salivation (vomition) Abortion - especially last trimester For soluble oxalate poisoning, go the Urogenital Menu.NECROPSY: Macroscopical findings: • Cyanosis• Tarry, dark, red-brown to brown blood• Tissues and mucous membranes brown (Not apparent in every case) • Congestion • Petechial and ecchymotic haemorrhages on mucosal, visceral and serosal surfaces.HISTOPATHOLOGY: • Nothing unusual or pathognomonic For soluble oxalate poisoning, go the Urogenital Menu.TREATMENT: 1. Methylene blue. Acts as intermediate electron acceptor that accelerates the reaction between NADPH and methaemoglobin. 2. Ascorbic acid. Also used in dogs for paracetamol poisoning.