Cyanide poisoning Flashcards Preview

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Flashcards in Cyanide poisoning Deck (26):
1

Cyanide is also known as...

hydrogen cyanide (HCN)
hydrocyanic acid
prussic acid

2

What cyanogenic plants do large animals most commonly get poisoned from?

Wild cherry (prunus spps)
Sudan grass, johnson grass, and sorghums
***these contain cyanogenic glycosides that can liberate toxic amounts of HCN

3

What cyanide plants or products may small animals be exposed to?

Fumigant rodenticide: Hydrogen cyanide gas
fertilizers
sodium nitroprusside - hypotensive drug
Combustion of plastic compounds - produces HCN gas
Plants: Cherris, apples. plumes, apricots, some spps of lima bean and cassava root (tapioca)

4

Clinical signs of cyanide poisoning are similar to poisoning from what toxic gas?

Carbon monoxide

**both will make the blood BRIGHT red

5

What kind of gas is HCN?

Volatile

**has a characteristic odor: bitter almond or ammoniacal

6

T/F: HCN is irritating to MM

TRUE

7

T/F: Cyanide has antithyroid effects

FALSE

Thyiocyanate (SCN) has antithyroid effects but not cyanide

8

What does the CN- radical bind with and form complexes with in the blood?

ferric iron, cupric, and molybdenum
*very active binding

9

Greater than _____ppm in a plant is toxic

200ppm

10

The acute oral MLD of HCN is ____ mg/kg in all species

2 - 2.3 mg/kg = highly toxic

11

What species factors will affect the degree of cyanide toxicity?

Ruminants are more susceptible than horses and swine
**hydrolysis by the rumen microflora causes release of cyanide from cyanongenic plants

*sheep are less susceptible than cattle

12

What plant factors will increase cyanide toxicity?

Damage to the plant will increase and cause hydrolysis of cyanogenic glycosides and release of cyanide (HCN)

*stunting, wilting, trampling, frost, drought, treatment with Phenoxy derivatives of fatty acids herbicides

13

What cyanogenic plant parts of the most toxic?

SEEDS
then leaves, bark, stems, fruit (highest to lowest)

14

What plant stage is the most toxic (HCN)?

Young and growing plants bc they contain more glycosides

15

What soil condition may increase HCN accumulation in plants?

High nitrogen and low phosphorus may increase glycoside

16

How is cyanide absorbed?

Through the GIT, inhalation, and via skin contact -- then distributed throughout the body

17

In the presence of thiosulfate, CN- is metabolized to what in the serum and liver?

Metabolized by sulfurtansferase to thiocyante (SCN) which is less toxic and is excreted in the urine

*has an antithyroid effect

*small amounts of HCN will be excreted in the urine or in expired air

18

What is the MOA in acute cyanide poisoning?

Excess CN in the blood and tissues binds with ferric iron and cupric copper of the mitochondrial cytochrome oxidase - This blocks the electron transport chain -inhibits the cells to utilize available oxygen resulting in histotoxic anoxia - particularly to the brain (***since the tissues can not utilize the oxygen - blood will have extra O2 and be bright red)

*decrease cellular energy
*increase anaerobic glycolysis - acidosis
*Vascoconstriction
*irritation to the MM

**this is a similar MOA as hydrogen sulfide - but with H2S blood will be dark brown and have odor

19

What is the MOA in chronic cyanide poisoning?

Neuronal degenration and demyelination of the spinal cord and brain

low levels of cyanide are goitrogenic due to thiocynate

20

What clinical signs are associated with acute cyanide poisoning?

**extremely rapid onset**
Animals may die without manifesting CS
Tachypnea, anxiety, panting, gasping, behavioral alarm, salivation, muscle tremors, lacrimation, urination/defecation, colic, vomiting, convulsions.. sudden death (only takes 4-5mins)

21

What clinical signs are associated with chronic cyanide poisoning?

posterior paralysis, urinary incontinence, cystitis, constipation, goitrogenic effect

22

What lesions are associated with cyanide poisoning?

Bright red blood and MM - blood may not clot
GIT and lungs - petechiation
Plants may be in rumen contents
+/- the smell of cyanide

23

what specific test can be used to detect cyanide in rumen contents or in plants?

Sodium picrate paper test (commercial test kit)
*yellow color will change to red in a few minutes in an airtight jar

other tests: urine for thyiocynate, lactic acidosis and increased ion gap - good indicators

Chemical analysis on many other samples, and forage - not helpful for ER situations

24

What is the specific treatment for cyanide poisoning?

Sodium Nitrate 20% IV

this will immediately improve perfusion - vasodilation
*causes methemoglobin which can bind the cyanide and reactivate cytochrome oxidase

Sodium thiosulfate 20% IV

This converts CN to thyiocynate (SNC) which is less toxic and excreted in urine
*can be giving orally

OTHER:
*O2 therapy and nitrite thiosulfate
*Vinegar and cold water orally to slow down microbial hydrolysis
*mineral oil laxative

25

T/F: Activated charcoal is effective for adsorption of cyanide

FALSE

26

T/F: There is a specific and effective treatment for chronic cyanide poisoning

FALSE

no treatment - prognosis will depend on have severe the neuronal degeneration and demyelination
*damage is usually irreversible