Exam 2 Study Guide Flashcards
Nitrate Sources
forages, fertlizers, natural sources, contaminatied water tanks
Especially drought stress
2.4-D application
Nitrate
MOA
ferrous to ferric iron in heme = methemoglobin → tissue anoxia
BROWN BLOOD
Nitrate:
Species most at risk
Ruminants mainly at risk → have to convert nitrAte to NitrIte - acute death
Monogastrics pretty resistant to nitrate
Nitrate
Antidote
Methylene blue
ILLEGAL
Nitrate
Best Diagnostic Samples
Antemortem: serum
Postmortem: OCular fluid nitrate >20ppm
Nitrate conversion will continue after death so rumen content no good
Sulfate / Polio
Sources
Dietary sulfur to H2S in rumen → inhaled/absorbed
Directly cytotoxic
Water and feed sources are additive
0.4% total ration
Sulfate / Polio
Laminar Cortical Necrosis
Polioencephalomalcia
Sulfate / polio
Clinical Signs
Head pressing, blindness, ataxia
Sulfate / Polio
Treatment
thiamine
NPN
Sources
feed additives, fertilizers
Animals can acclimate
NPN
MOA
Urea to ammonia vie urease
Ammonia to ammonium - not absorbed
Elevated pH selects for Ammonia, usually converted back to urea in liver
Liver detox pathway gets overloaded → ammonia stays in circulation → hyperammonemia → Nervous System Affected
NPN
Clinical Signs
tremors, agitation, lateral recumbency, convulsions, acute death
NPN
Diagnosis
Antemortem = Clinical signs after feed change, elevated rumen pH
Post-mortem = Ocular fluid ammonia >20ppm
NPN
Treatment
Vinegar and cold water
Dilute, drop pH, cool temp
Mycotoxin
General
young animals, particularly swine generally most susceptible
Common in grain sources, often more than one mycotoxin present
Tough diagnosis, almost diagnosis of exclusion
Mycotoxin:
Ergot/fescue
Hyperthermia, distal gangrene, lameness, agalactia, delayed parturition
Mycotoxin:
DON / Vomitoxin
Feed refusal, vomiting in swine
Mycotoxin:
Zearalenone
Estrogenic compound
Mycotoxin:
Aflatoxin
Hepatotoxin in may species, only one regulated
Mycotoxins:
Fumonisin
Equine leukoencephalomalacia
procine pulmonary edema
minor liver lesions common
Mycotoxins:
Ochratoxin / citrinin
Nephrotoxic
Mycotoxins:
Slaframine
“Slobber factor”
Gossypol
Source
toxic compound produced by cotton to protect cottonseed
Cottonseed common feed component esp. for dairy cows
Gossypol:
Target organs
heart and other muscle
Gossypol:
Clinical signs
Acute death vs, chronic heart failure
Suppresses sperm production in males
Gossypol:
Free vs bound
free is toxic
bound is not toxic
Selenium
Acute
Cases generally from injections
Very rapid death
Selenium
Sub-chronic:
Hind limb ataxia / paralyssi and hoof lesions in pigs
Poliomyelomalacia
Selenium
Chronic
Usually form dietary selenium
Takes weeks to months
Hair and hoof lesions → Lameness
Selenium:
Obligate Accumulators
Astragalus
Oonopsis
Stanleya
Xylorrhiza
Selenium
Vitamin E/Selenium Deficiency
Nutritional myopathys, white muscle disease, mulberry heart disease, hepatosis dietetica
Selenium
Diagnosis
Whole blood best
Selenium
Treatment
NONE
Differentails
Myopathies in Cattle
Vitamin E / Selenium deficiency
Ionophore intoxication
Acute selenosis
Gossypol
Laminar Cortical Necrosis
Salt
Sulfur
Lead
Lameness in Horses
Fescue / ergot
Chronic selenium
Fluoride
Black walnut
Ionophore (myopathy may look like lameness)
Acute death in adult cows
Nitrate
Urea/NPN
OP/Carbamates
Cyanide
Hemlocks
Taxus sp. / Japanese Yew
Blue-green algae
Blue-green Algae
Environmental conditions
Warm, stagnant, nutrient rich waters in LATE summer
Usually lower oxygen, oxygenation maybe even preventative
BGA
Hepatotoxins
Massive hepatocellular necrosis (hours to days)
Vomiting, diarrhea, liver enzyme necrosis
Clotting issues = hypovolemic shock
MICROCYSTIN
BGA
Neurotoxins
NO lesions (minutes to hours)
Ataxia, tremors, seizures, rapid death
ANATOXIN-a, Guanitoxin
Death due to respiratory paralysis
Na+ toxicosis, Water Deprivation
Water deprivation or excess sodium consumption
Na+ toxicosis, Water Deprivation
MOA
Sodium moves into brain → impairs sodium pump → Water follows after rehydration → cerebral edema, neuronal necrosis → Laminar Cortical necrosis
Na+ toxicosis, Water Deprivation
Species most susceptible
SWINE
Eosinophilic perivascular cuffing
Can affect all animals
Na+ toxicosis, Water Deprivation
Diagnosis
Histopath + brain sodium >1800ppm
