Equis ISSN 2398-2977

Toxicity: slaframine

Synonym(s): Slaframine poisoning, Slobber factor

Contributor(s): Karyn Bischoff, Birgit Puschner

Introduction

  • Cause: slaframine is a mycotoxin produced by Rhizoctonia legumincola, which parasitizes legume forages, most commonly Trifolium pratense (red clover).
  • Signs: most commonly hypersalivation.
  • Diagnosis: hypersalivation, grazing legume forage, black spots on legume leaves.
  • Treatment: clean feed.
  • Prognosis: excellent.

Pathogenesis

Etiology

  • Slaframine, produced by the fungus Rhizoctonia legumicola:
    • Present in soils.
    • Grows well in wet, humid climates.
    • Parasite of legumes, most commonly Trifolium pratense (red clover), but other species can be affected.
    • Affects fresh forage and hay.
    • Presents as 'black patch disease' on plant; brown to black rings on leaves and stems.
    • Black patch is more common during summer periods.
    • Parasympathomimetic mycotoxin.
    • Stimulates muscarinic receptors:
      • Salivation.
      • Lacrimation.
      • Urination.
      • Diarrhea.
      • Bradycardia.

Predisposing factors

General

  • Red clover or other legumes in pasture or hay; presence of black patch disease.
  • The fungus is ubiquitous in soil.

Specific

  • Rhizoctonia legumicola grows well in cool humid weather.
  • Slaframine production is favored if temperature exceed 25°C/77°F.

Pathophysiology

  • Slaframine:
    • Mycotoxin.
    • Activated by hepatic microsomal enzymes to 6-ketoimine.
    • Mimics acetylcholine at muscarinic receptors:
      • Salivation (most common).
      • Lacrimation.
      • Urination.
      • Diarrhea.
      • Bradycardia (uncommon).

Timecourse

  • Onset can occur within 1-6 h of exposure to contaminated feed.
  • Recovery can take up to 4 days.

Epidemiology

  • Usually, multiple horses on the same pasture or hay are effected.

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.
  • Osweiler G D (2001) Mycotoxins. Vet Clin North Am Equine Pract 17 (3), 561-562 PubMed.
  • Plumlee K H & Galey F D (1994) Neurotoxic mycotoxins: a review of fungal toxins that cause neurological disease in large animals. J Vet Intern Med 8 (1), 49-54 PubMed.
  • Riet-Correa F et al (2013) Mycotoxicoses of ruminants and horses. J Vet Diagn Invest 25 (6), 692-708 PubMed.
  • Socket D C, Baker J C & Stowe C M (1982) Slaframine (Rhizoctonia leguminicola) intoxication in horses. JAVMA 181 (6), 606 PubMed.
  • Wijnberg I D, van der Ven P J & Fink-Gremmels Gehrmann J (2009) Outbreak of salivary syndrome on several horse farms in the Netherlands. Vet Rec 164 (19), 595-597 PubMed.


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