Exam 2: Nitrate and Cyanide Poisoning Flashcards
What are common plants associated with Nitrate Poisoning?
List plants pictured in powerpoint.
Kochia weed (Kochia scoparia)
Lambs quarter (Chenopodium spp.)
Sudan grass (Sorghum sudanensis and hybrids)
sunflowers (Helianthus spp.)
and Russian thistle (Salsola iberica)
What is the mechanism of action for nitrate poisoning?
The rate at which nitrate is converted to highly toxic nitrite is dependent on the nitrate adaptation of microorganisms in the rumen, the rate and amount of nitrate ingested, and the amount of carbohydrate available in the rumen. Experimental data suggest that nitrate poisoning is more likely to occur in ruminants after several days of feeding high nitrate forages. Others have demonstrated that nitrate adapted rumen microflora more completely reduce nitrate beyond nitrite to ammonia. Similarly, when carbohydrates such as corn and molasses are present in the rumen, nitrates are more rapidly converted to microbial proteins without the accumulation of nitrite. Low energy diets on the other hand increase the animal’s susceptibility to nitrite poisoning.
What are clinical signs for nitrate poisoning?
The signs of nitrite poisoning in ruminants include drowsiness, weakness, followed by muscular tremors, increased heart and respiratory rates, staggering gait and recumbency. These signs are exacerbated by stress or forced exercise. Examination of the mucous membranes usually reveals a brownish discoloration that is best observed in the vaginal mucous membranes. Brown /muddy mucous membranes are detectable once there is more than 20% methemoglobinemia.
What are dangerous levels of nitrate in feed?
As a general rule, levels of nitrate in feed over 0.5%, and water levels exceeding 200 ppm are potentially hazardous to pregnant animals especially if fed continuously. Forages containing in excess of 1% nitrate dry matter should be considered toxic. Water levels of 1,500 ppm or greater are potentially toxic especially if consumed with forages high in nitrate.
What is the treatment for nitrate poisoning?
Animals showing signs of nitrate poisoning should be handled carefully to avoid excitement. The preferred treatment for nitrate poisoning is methylene blue solution administered intravenously. The recommended dose range for methylene blue for cattle, goats and sheep is from 4-15 mg/kg body weight administered as a 1-2% solution. A dose of 8 mg/kg body weight intravenously has been reported to be effective in cattle. The higher dosage may be required for severe nitrate poisoning. The action is rapid, within 15 minutes so the low end dosing may be repeated after 15 minutes to reduce methemaglobinemia to the point that the animal is not in severe respiratory distress. The administration of mineral oil (1 gallon for a 500 kg cow) orally via stomach tube will counteract the caustic effect of the nitrates on the gastrointestinal system, and will act to speed up the passage of the nitrates. Several gallons of cold water with added broad-spectrum antibiotics orally will help reduce further nitrate reduction to nitrite by rumen microorganisms. Similarly vinegar given orally has been helpful in preventing nitrate reduction in the rumen.
What plant components and gastric conditions contribute to Cyanide poisoning?
Dependent on growing conditions: Highest in new growth, Nitrate fertilization, Cool moist conditions. **Plant Stress: **Drought, frost, wilting, chewing. Horses, pigs and other simple stomached animals are less susceptible to oral cyanide poisoning because the highly acidic gastric secretions inactivate the enzymes. Rumin alkaline pH, high water content, and microorganisms favor HCN production.
What is the mechanism of action of cyanide poisoning?
Cyanogenic Glycosides hydrolyzed to HCN, HCN binds Fe+++and blocks cytochrome c oxidase activity, Prevents utilization of oxygen in the cells, Results in Oxygen saturation of hemoglobin and cellular anoxia.
What are common plants associated with cyanide poisoning?
name 8 in powerpoint.
Sorghums: Johnson grass (Sorghum halepense)
Choke Cherry (Prunus virginiana)
Service berry (Amelanchier alnifolia)
Elderberry (Sambuccus canadensis)
Mountain mahogony (Cercocarpus montanus)
Arrow Grass (Triglochin maritima)
Poison Suckleya (Suckleya suckleyana)
Blue Flax (Linum lewisii)
What are clinical signs of cyanide poisoning?
Sudden Death – often within 1-2 hours (lethal dose ≅ 2 mg/kg or 3 mg/L in blood)
Cherry Red Venous Blood if examined immediately after death. Dilated pupils, Ataxia, muscle tremors /convulsions, increased heart rate (0.5 – 1mg/L). Acute Respiratory difficulty (2.5 mg/L)
Lesions (few). Pink mucous membranes, prolonged clotting. Generalized congestion /some hemorrhages in heart, lungs, other organs.
What is the treatment for cyanide poisoning in livestock?
Sodium nitrite (10-20 mg/kg b.w. animals IV) or inhaled amyl nitrite (0.3 ml vial)
Forms methemoglobin which binds cyanide to form cyanmethemoglobin.
This releases Cytochrome oxidase and mitochondrial respiration resumes.
Sodium Thiosulfate (500 mg/kg b.w. IV) Cyanide → Thiocyanate For ruminants 20% solution 3ml/cwt i.v. (1-2 gallons of solution orally)
What is the treatment for cyanide poisoning in dogs?
Sodium nitrite (10-20 mg/kg b.w. animals IV) or inhaled amyl nitrite (0.3 ml vial)
Forms methemoglobin which binds cyanide to form cyanmethemoglobin.
This releases Cytochrome oxidase and mitochondrial respiration resumes.
Hydroxycobalamin – Vitamin B12a (70mg/kg IV over 15 minutes) – dogs
Chelates cyanide to release cytochrome oxidase. If uncertain if symptoms due to Nitrite or Cyanide – Methylene Blue may be effective
