Unit 2 - Nitrate and Cyanide Flashcards
What are the sources for nitrogen toxicosis (general)?
Plants, stunted plant growth, stressors, and non-plant sources
The lower you go on corn, the (lower/higher) the concentration of nitrate.
higher
What are the non-plant sources of nitrate? Nitrite?
Nitrate - Water, fertilizer, gunpowder, explosives
Nitrite - pickling and curing brines, gunpowder, and explosives
What is the MOA of nitrate toxicosis?
- Nitrate (NO3) is converted in the rumen to nitrite (NO2)
- Nitrite is either converted to ammonia for microbial growth or there is excessive nitrite
- Excessive nitrite overwhelmes bacteria
- Nitrite goes into the blood
- Nitrite oxidizes ferrous iron to ferric iron
- Methemoglobin is produces
What does methemoglobin do in the body?
It can’t carry oxygen which decreases O2 flow to tissues resulting in death by anoxia
What does methemoglobin do to the color of blood?
It colors it brown
What species are the most susceptible to nitrate toxicosis?
Ruminants
What species are resistant to nitrate?
Horses, pigs, dogs, humans
What species are suscpetible to nitrite toxicosis?
All species
Why are monogastrics not susceptible to nitrate?
Because it cannot be broken down to nitrite in their tum tums
What are the predisposing factors to nitrate toxicosis?
Rate of consumption, low energy diets, lack of adaptation, and methemoglobin reductase activity
When is the onset of clinical signs for nitrate toxicosis?
Within minutes to several hours
What clinical signs are associated with nitrate toxicosis?
Weakness and ataxia Cyanotic Chocolate colored blood Collapse Respiratory distress Abortions Death
What samples can be collected for methemoglobin levels?
Ocular fluid, serum, and blood
What sample can be taken to detect Nitrate/nitrite levels?
Feed, forage, water
What lesions are associated with nitrate toxicosis?
Congested and muddy tissues
What are the general steps for nitrate toxicosis diagnosis?
Chocolate brown blood
History of exposure
High ocular fluid or serum nitrate/nitrite concentrations
Detection of high nitrate/nitrite levels
How do you diagnose bovine abortions due to nitrate?
- Dam exhibits clinical signs of nitrate toxicosis
- Abortion with 1-2 weeks after onset in surviving dams
- Fetal ocular fluid nitrate > 20 ppm
How is nitrate toxicosis treated?
Prevent further exposure
‘Antidote’: methylene blue
Cold water and oral penicillin
T/F: Methylene blue is the legally approved antidote for nitrate toxicosis in livestock.
False - there is no FDA legally approved antidotes for livestock
How is nitrate toxicosis prevented?
ID and understand the major sources and circumstances for nitrate
Introduce ruminants to high risk forages slowly
Provide readily utilized energy source
What human health concern is associated with nitrate?
Blue baby syndrome - low acid in gut resulting in higher bacterial populations and ultimately methemoglobinemia
What are the synonyms for cyanide?
Cyanide, hydrocyanic acid, prussic acid, and hydrogen cyanide
What are the sources for cyanide toxicosis?
Fumigants, pesticides, cyanide salts, fires, and plants
When is the greatest cyanide potential in forages?
Greatest during early growth and then declines
What increases cyanogenic concentration in forages?
Drought stress, increase temperature, shading, fertilizaiton, insect damage
What converts cyanogenic glycoside to cyanide?
Physical damage to the plant results in release of intrinsic enzymes and the hydrolysis of cyanogenic glycoside to cyanide
What physical damage can result the conversion of cyanogenic glycoside to cyanide?
Freezing, crushing, macerating, and cutting
How do you avoid feeding cyanide to in baled forage to livestock?
Wait 72 hours after bailing to feed it - if you feed green chop its dangerous
T/F: Cyanide can be detoxified endogenously.
TRUE
What detoxifies cyanide endogenously?
Thiosulfate
T/F: Cyanide effects are cumulative.
False - they arent
T/F: Cattle can handle 4-5 times the lethal dose if administered slowly throughout the day.
TRUE
What is the MOA of cyanide toxicosis?
- Cyanide ion combines with Fe in cyochrome oxidase system
- Inhibits reduction of O2 within ETC
- Inhibits transfer of O2 to tissues
- Inhibited cellular respiration
- anoxia
What species are more susceptible to cyanide toxicity? Why?
Ruminants - The rumen microbes hydrolyze cyanogenic glycoside to cyanide
Why are monogastrics less susceptible to cyanide?
There is decreased cyanogenic glycoside hydrolosis
In order for cyanide toxicosis in monogastrics, what needs to happen?
They must consume raw plant material
T/F: All species are susceptible to cyanide gas.
TRUE
When is the onset of clinical signs for cyanide toxicosis?
Minutes to < 1hr
What clinical signs are associated with cyanide toxicosis?
Anoxia & ataxia Dyspnea Excitement and muscle tremors Collapse Seizures, coma, death Bright 'cherry' red mucous membranes
How do you test for cyanide levels?
Whole blood Rumen/stomach contents Liver Brain Forage/plant material Suspcted substance
How is cyanide toxicosis treated?
Sodium nitrite in combination with sodium thiosulfate
What is the mechanism of treatment for cyanide toxicosis?
- Na nitrate
- MetHb
- CNMetHb
- CN binds to thiosulfate
- Excreted as thiocyanate
What is an alternate option of treatment for cyanide toxicosis?
Methylene blue - it reduces excess MetHb
If the diagnosis of cyanide toxicosis is unclear, what should you give for treatment?
Methylene blue because you don’t want to cause nitrate poisoning
What cyanide derivatives/products are of risks to humans?
Cyanide traps, terrorist/warfare agent, and seeds of fruit
