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PLEASE NOTE:
"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

Miserotoxin Poisoning

Some of the Astragali which poison primarily through miserotoxin that have a large enough range and population to be a problem are:

  • A. convallarius - Lesser Reedy Milkvetch
  • A. emoryanus - Emory Milkvetch
  • A. falcatus - Russian Sickle Milkvetch
  • A. miser - Weedy Milkvetch or Timber Milkvetch
  • A. tetrapterus - Four Wing Milkvetch
  • A. whitneyi - Whitney Milkvetch

    (James and Walsh 1992)

These species synthesize either 3-nitropropanol or 3-nitropropionic acid (but not both) in the form of a beta-D-glucoside: miserotoxin. Those bearing nitropropanol have higher potential toxicities.

Miserotoxin poisoning shows two main types of symptoms:

  • Neurological Deficit
  • Respiratory Difficulty

Early signs of poisoning are the development of a placid, stupefied state, excessive frothy salivation and increasing incoordination. The symptoms of further poisoning vary according to whether it is acute or chronic. In both cases, the animals can die from respiratory failure after a sudden stress - don't allow animals that have been poisoned to exert themselves. (Majak, Cheng, Muir 1984)

Acute Poisoning

The symptoms that characterize acute miserotoxin poisoning are: severe respiratory distress, weakness in the hind legs, recumbency, paddling motions, coma and death.

Chronic Poisoning

The effects of chronic poisoning are primarily neurological in nature. The symptoms are: incoordination of the hind limbs (e.g. knocking or crossin gthe hind legs), knuckling of the fetlock joints, weight loss and difficult breathing with sudden exertion.

Lesions associated with miserotoxin poisoning are focused sites of necrosis and swelling of the myelin in the brain and spinal cord. Although the pathology of this toxicosis is not well characterized, work is ongoing. (Pass 1994, Majak et al. 1984)

Miserotoxin Biochemistry
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