bovis - Articles
Foxglove toxicity
Synonym(s): Digitalis purpurea toxicity
Introduction
- Cause: ingestion of any part of the foxglove plant (Digitalis spp).
- Signs: diarrhea, cardiac arrhythmias, rapid, weak, irregular pulse, increased respiratory rate, abdominal pain or sudden death
- Diagnosis: clinical signs and blood sample for detection of digitalis glycosides.
- Treatment: unlikely to be cost effective, but suggestions are listed below.
- Prognosis: dependent on quantity consumed and size of animal.
Geographic incidence
- Foxgloves are native to Europe, western and central Asia and northwest Africa, but naturalized in the US and Canada
.jpg)
. - Found in open woods, clearings, hedgerows and footpaths. Also wildly cultivated.
- Grows up to 2 m in height.
- Biennial.
- Leaves: oval-lanceolate.
- Flowers grow on a tall spike:
- They are pink to purple, sometimes white or yellow, with characteristic tubular bell-shape.
- The flowers open in succession from the base upwards (May to September).
- The fruits are capsules containing numerous seeds.
Cost considerations
- Multiple animals may be affected with associated costs for veterinary care.
- Hospitalization may be required for animals with significant signs, but treatment is unlikely to be cost effective.
- Food safety issues for milk.
Special risks
- Cardiac glycosides may pass into milk.
Pathogenesis
Etiology
- Livestock are infrequently poisoned, due to the unpalatable nature of the plant, but may ingest the plant either fresh or dried in hay.
- Some animals have been reported to actively seek the plant to graze on it.
- Foxgloves remain toxic when dried.
Predisposing factors
General
- Access to plants.
- Lack of or inability to access other forage.
Pathophysiology
- All parts of the plant are toxic, including the dried leaves.
- The plant contains several cardiac glycosides (digoxin Digoxin, digitoxin and their genins).
- Cardiac glycosides are negative chronotropes and positive inotropes; that is, they cause decreased frequency and increased force of contraction of heart muscle.
- 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 including first- and second-degree heart block and ventricular tachycardia. Pulse may be rapid, weak and irregular.
Timecourse
- Clinical signs usually occur within 6 h of ingestion.
- When poisoning occurs, the clinical signs may be severe and dramatic.
- Death may occur rapidly or up to 36-48 h after ingestion.
Diagnosis
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Treatment
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Prevention
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Outcomes
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Further Reading
Publications
Refereed Papers
- Recent references from PubMed and VetMedResource.
- Falciola C, Davanzo F, Rivolta M, Molino L & Colombo M L (2015) Nerium oleander: case report of a severe poisoning case involving numerous cows [abstract]. Clin Toxicol 53 (7), 753.
- Wijnberg I D, van der Kolk J H & Hiddink E G (1999) Use of phenytoin to treat digitalis-induced cardiac arrhythmias in a miniature Shetland pony. Vet Rec 144 (10), 259-261 PubMed.
- Rezakhani A & Maham M (1992) Oleander poisoning in cattle of the Fars Province, Iran. Vet Human Toxicol 34 (6), 549 PubMed.
- Thomas D L, Quick M P & Morgan R P (1987) Suspected foxglove (Digitalis purpurea) poisoning in a dairy cow. Vet Rec 120 (13), 300-301 PubMed.
- Mahin L, Marzou A & Huart A (1984) A case report of Nerium oleander poisoning in cattle. Vet Hum Toxicol 26 (4), 303-304 PubMed.
- Corrigall W, Moody R R & Forbes J C (1978) Foxglove (Digitalis purpurea) poisoning in farmed red deer (Cervus elaphus). Vet Rec 102 (6), 119-122 PubMed.
- Maclean A (1966) Suspected foxglove poisoning in sheep. Vet Rec 79 (25), 817-818 PubMed.
Other sources of information
- James L Voss (2019) Guide to Poisonous Plants. Colorado State University. Website: https://csuvth.colostate.edu.
- Burrows G E & Tyrl R J (2013) Toxic Plants of North America. 2nd edn. Wiley Blackwell, USA.
- Frohne D & Pfänder H J (2004) A Colour Atlas of Poisonous Plants: A Handbook for Pharmacists, Doctors, Toxicologists, and Biologists. Timber Press: UK.
- Cornell University Poisonous Plants Informational Database. Website: www.ansci.cornell.edu/plants.
- Cooper M R & Johnson A W (1998) Poisonous Plants and Fungi in Britain. 2nd edn. The Stationery Office, UK.
- Rezakhani A & Maham M (1994) Cardiac Manifestations of Oleander Poisoning in Cattle and Donkeys. In: Plant-associated Toxins: Agricultural, Phytochemical and Ecological Aspects. Eds: Colegate S M, Dorling P R, Allen J G, Huxtable C R & Panter K E. CAB International, UK. pp 534-537.
Organisation(s)
- ASPCA Animal Poison Control Center. Website: www.aspca.org/pet-care/animal-poison-control. Telephone: (888) 426-4435.
- Veterinary Poisons Information Service (VPIS). Website: www.vpisglobal.com. Telephone: + 44 (0) 2073 055 055.