| DISORDER: |
Prussic Acid |
| Plant Species: |
Primarily occurs in sorghums commonly less than 1½ foot. (johnsongrass, grain sorghum, sorghum-sudan), wild cherry, and occasionally on white clover and birdsfoot trefoil.Does not occur in pearl millet or corn. |
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| Conditions: |
Poisoning is associated with consumption of plant parts with high levels of prussic acid (HCN), by a cyanogenic compound that is highly poisoning. Prussic acid is associated with rapidly growing plants. Occurs in young plant tissue that is damaged or stressed, (for example: after a frost or drought after heavy N fertilization) or mechanically injured (after 4 wheelers or ATVs are run over a field). Under these conditions the cells are ruptured mixing their enzyme content with that of Dhurrin (a cyanogenic glycride in sorghums), breaking down dhurria to prussic acid. |
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| Causes: |
Plant HCN levels greater than 50 ppm dry mater basis or 200 ppm on wet basis. |
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| Mode of Action: |
Cyanogenic glucosides are converted by enzymatic hydrolysis to HCN (Hydrogen cyanide).HCN causes acute respiratory inhibition by inhibiting the enzyme cytochrome oxidase. |
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| Animal Symptoms: |
Labor breathing if detected early enough. May occur minutes (10-15 min) after consumption of feed. |
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| Treatment: |
Treat with sodium thiosulfate or methylene blue to detoxify CN. |
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| Prevention: |
If plants have been injured defer grazing until they are recovered from injury. After a hard freeze, or severe drought, avoid grazing for approximately 1 week. After a rain or irrigation on drought stressed fields wait at least 2 weeks after plants begin to grow before grazing. |
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| Notes: |
Due to volatilization of CN compounds, hay can be fed; however, you still need to monitor forage by taking samples and have them tested to confirm ‘safety’ in feeding the hay. Forage samples can be sent to:
- Texas Veterinary Diagnostic Medical Laboratory (TVMDL) to determine toxic levels for a fee of $15.00 in-state and $20.00 out-of-state samples.
Phone: (979)845.3414 or 1.888.646.5623, Fax: (979)845.1794
P.O. Drawer 3040, College Station, TX 77841-3040
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