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Bluebell (glycoside) poisoning
Synonym(s): Bluebell (Hyacinthoides non-scripta), Spanish bluebell (Hyacinthoides hispanica), Italian bluebell (Hyacinthoides italica)
Introduction
- Cause: ingestion of bluebells.
- Signs: anorexia, depression, signs of abdominal pain, weakness and weak pulse.
- Diagnosis: based on history of exposure and clinical signs.
- Treatment: supportive.
- Prognosis: poor in animals with significant clinical signs.
Presenting signs
- Sudden death.
- Depression.
- Signs of abdominal pain.
Acute presentation
- Gastrointestinal signs.
- Depression.
- Weakness.
- Reduced rumen motility.
Geographic incidence
- Bluebells are found from north-western Spain to the British Isles and are also frequently grown as a garden plant.
- The bluebell is native to woods, hedgerows, shady banks and wet grassland throughout Britain and Ireland, and the Italian and Spanish bluebells are naturalized in these habitats.
Public health considerations
- Cardiac glycosides may pass into milk, although the risk of poisoning by this route is likely to be low and has not been reported with bluebells.
Cost considerations
- Multiple animals may be affected with associated costs for veterinary care. Hospitalization may be required for animals with significant signs.
- Food safety issues for milk.
Pathogenesis
Etiology
- Exposure generally occurs in the spring
. - Exposure could occur through ingestion of contaminated hay, although such cases have not been reported at the time of publication.
Predisposing factors
General
- Access to bluebells.
- Lack of or inability to access other forage.
Pathophysiology
- All parts of these plants contain scillarens, which are cardiac glycosides similar in structure to those of foxglove (Digitalis spp).
- Glycosidase-inhibiting alkaloids have also been described in bluebells and may contribute to the toxic effects.
- The cardiac glycosides found in plants are generally precursors: primary glycosides that undergo enzymatic hydrolysis when plant material is dried or damaged to give the active (or secondary) glycosides.
- Cardiac glycosides also interfere with the cellular membrane sodium-potassium (Na+ -K+ ATPase enzyme system) pump resulting in depletion of intracellular potassium and an increase in serum potassium. This causes irregular heart activity, and eventual complete block of cardiac conduction.
- They also have irritant effects on the gastrointestinal tract.
- Cardiac glycosides can result in cardiac arrhythmias. Dysrhythmias Dysrhythmias including first- and second-degree heart block and ventricular tachycardia. Pulse may be rapid, weak and irregular.
Timecourse
- Limited information in cattle.
- Signs are expected to occur within a few hours with recovery within 1-3 days.
Epidemiology
- Poisoning can occur wherever bluebells grow.
- Cases in cattle are rarely reported.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed Papers
- Recent references from PubMed and VetMedResource.
- Payne J & Murphy A (2014) Plant poisoning in farm animals. In Pract 36 (9), 455-465 VetMedResource.
- Cutler K (2007) A case of suspected bluebell (Hyacinthoides non-scripta) poisoning in cattle. UK Vet 12 (2), 44-47 VetMedResource.
- Watson A A, Nash R J et al (1997) Glycosidase-inhibiting pyrrolidine alkaloids from Hyacinthoides non-scripta. Phytochemistry 46 (2), 255-259.
- Thursby-Pelham R H (1967) Suspected Scilla non-scripta (bluebell) poisoning in cattle. Vet Rec 80 (24), 709-710 PubMed.
Other sources of information
- Burrows G E & Tyrl R J (2013) Toxic Plants of North America. 2nd edn. Wiley Blackwell, USA.
- Cooper M R & Johnson A W (1998) Poisonous Plants and Fungi in Britain. 2nd edn. The Stationery Office, UK.
Organisation(s)
- ASPCA Animal Poison Control Center. Tel: +1 (888) 426 4435; Website: www.aspca.org.
- Veterinary Poisons Information Service (VPIS). Tel: +44 (0)2073 055 055; Website: www.vpisglobal.com.