Canis ISSN: 2398-2942

Toad poisoning

Introduction

  • Cause: all toads are poisonous either by being eaten or by being mouthed.
  • The native British toad,Bufus vulgarisis much less toxic than some exotic species, egBufus blombergi,Bufus alvarius,Bufus marinus.
  • Signs: inflammation of the mouth and pharynx with ptyalism and retching, abdominal pain, vomiting, neurological and cardiovascular effects.
  • In Britain the signs are usually confined to local oral effects. Contact with exotic toads are more likely to cause the more severe systemic effects and these may be fatal.
  • Treatment: symptomatic.
  • Prognosis: good following exposure to native UK toads; guarded otherwise.

Pathogenesis

Etiology

  • Mouthing or eating toads.
  • Very occasionally there may be absorption of toxins through an open wound.

Pathophysiology

  • Toad poisoning is most likely to occur in the summer when toads can be easily found in gardens.Bufus vulgarishibernates in the winter and in the spring is found breeding in ponds.
  • Venom is produced from toad skin glands as a defence mechanism.
  • The glands are concentrated on the dorsal body, especially in the paratoid glands on the back of the neck.
  • Using an active muscular process the glands can quickly exude a venomous liquid.
  • Venoms produced are said to be bufagins, bufotoxins, bufotenins and other compounds.
Bufagins
  • Have actions like digitalis such as ventricular fibrillation.
Bufotoxins
  • Cause blood pressure rise (if given intravenously), cardiac dysrhythmias and dyspnea and are said to be the most important group clinically.
Bufotenins
  • Like oxytocin Oxytocin and also like substances found in some hallucinogenic plants.
Other substances
  • Adrenalin, cholesterol, ergosterol and 5-hydroxytryptamine (serotonin) are found in toad venom.
  • Mucous is produced from the skin at the same time as the venom as an additional protective device.
  • Toad venom is sticky and difficult for the affected animal to remove from their mouth.
  • Local irritation is the usual problem in Britain.
  • Venom in the mouth and pharynx is sticky and irritant.
  • Systemic signs are only likely with the British toad if it is eaten or if the affected dog is small or has an underlying problem such as asthma Eosinophilic bronchitis/pneumonia or heart disease Congenital heart disease: overview.

Timecourse

  • It is a peracute onset for local irritation, ptyalism and retching.
  • Systemic signs take about 24 h.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Johnnides S, Green T & Eubig P (2016) Toad intoxication in the dog by Rhinella marina; the clinical syndrome and current treatment recommendations. JAAHA 52 (4), 205-211 PubMed.
  • Palumbo N, Perri S & Read G (1975) Experimental induction and treatment of toad poisoning in the dog. JAVMA 167 (11), 1000-5 PubMed.
  • Bedford P G (1974) Toad venom toxicity and its clinical occurrence in small animals in the UK. Vet Rec 94 (26), 613-614 PubMed.
  • Perry B D & Bracegirdle J R (1973) Toad poisoning in small animals. Vet Rec 92 (22), 589-590 PubMed.
  • Otani A, Palumbo N & Read G (1969) Pharmacodynamics and treatment of mammals poisoned by Bufo marinus toxin. Am J Vet Res 30 (10), 1865-72 PubMed.

Other sources of information

  • Palumbo N E & Perri S F (1983) Toad poisoning. In:Current Veterinary Therapy VII.W B Saunders, Philadelphia, pp 160-162.

Organisation(s)


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