Equine Toxicology Flashcards
What are the major plant + environmental neurotoxins?
*Deadly nightshade
*Hemlock
*Flatweed
*Bracken fern
*Mare’s tails
*Endophyte infected ryegrass
*Mouldy corn
*Aflatoxins
*Botulism
*Blue-green algae
*Lead
What is the agent thats known as deadly nighshade?
*Atropa belladonna - tropane alkaloids (toxic agent)
What are the atropine related signs of deadly nightshade?
*Mydriasis
*Shivering / muscle spasms
*Tachycardia
*Dry MM
*COLIC
*Haematuria
What is the genus + species of hemlock? What does it cause?
*Conium maculatum - piperidine alkaloid coniine = skeletal muscle paralysis
Death from respiratory paralysis
What causes stringhalt signs?
Flatweed - end of axons die off - weird gait
What are the clinical signs of bracken fern ingestion?
Bracken staggers = anorexia, cardiac dysarrhythmia, incoordination, convulsions, clonic spasms
What is seen with Mare’s tails? Tx?
*Same as bracken fern - CNS signs
*Tx = thiamine
What does mouldy corn poisoning cause? Mycotoxins
*Anorexia, blindness, ataxia, seizures + death
*Causes softening of white matter of brain
What does rye-grass staggers cause?
*Trembling, unsteadiness + poor muscle coordination
What are bacterial neurotoxins? What do they cause?
*Botulism (Cl. botulinum) = flaccid paralysis + dysphagia
*Tetanus (Cl. tetani) = hypertonia + hyperflexia
Tetauns in humans = locked jaw
*Equine grass sickness = equine dysautnomia
Why is blue-green algae dangerous?
Highly toxic = sudden death
What are signs of lead poisoning?
*Depression
*Facial + laryngeal/pharyngeal paralysis (inhalational pneuomonia)
*Anal / bladder paralysis
*Blindness, seizures, coma + death
*Can cross placenta = premature / weak / stillborn foals
*colic
*Diarrhoea
*Hepatic failure
What are major plant + environmental cardio-respiratory toxins?
*Sorghum
*Foxglove
*Oleander
*Yew
*Rhododendron
*Monesin
What are the toxic agents of Oleander, Rhododendron + Foxglove?
*Oleander = cardiac glycosides
*Rhododendron = polyol andromedotoxin
*Fox glove = cardiac glycosides
What is toxic in yew?
*Alkaloid toxins = acts on cardiac myocytes = heart failure
What does monesin cause in horses?
*Dilated cardiomyopathy
*Acute = Sudden death
*Chronic = heart failure
What are major hepatotoxins?
*Pyrrolizidine alkaloid containing plants (ragwort)
*Aflatoxins - aspergillus
What are myotoxins? (muscle) +CS?
*Sycamore trees - hypoglycin A
*CS = weakness, recumbency, red urine, increased serum muscle enzymes
What are enterotoxins? CS?
*Oak / acorns - poisoning rare in horses
*Colic, tenesmus, haemorrhagic diarrhoea
What are major plant dermatoxins?
*St Johns Wort
*Giant Hogweed
=Causes photosensitisation - will affect white haired areas
What can selenium toxicity cause?
Affect keratin = hairloss + laminitis
What are general principles of Tx?
*Remove toxic agent
*Empty GI tract of toxin
*Reduce absorption - activated charcoal
*Specific antagonist
