Final Exam Flashcards
What factors in plants increases risk of mycotoxin production?
Stress due to drought, flooding, poor soil fertility
How are mycotoxins distributed in feed?
Unevenly, in pockets. Toxins can persist after fungi are gone.
What animals are most susceptible to mycotoxins?
Monogastrics are at highest risk (poultry, swine), Horses are monogastrics, but at less risk, ruminants least susceptible, but pre-ruminants are fully susceptible
What is the potential role of mycotoxin contamination in causing animal health problems?
If animals eat contaminated feed can cause drop in production directly or due to secondary infection.
What are the risk factors associated with the formation of mycotoxins in feed ingredients? Does mold mean that there is mycotoxin present?
Stress to plants, less likely in surface “spoilage” organisms, more likely to produce mycotoxins if infecting living tissues, highly dependent on environmental factors and mold ≠ mycotoxins.
What are some feeding situations that could be associated with ingestion of mycotoxins?
Monogastric animals eating corn or cereal grains. Whole oil seeds. Cattle eating mycotoxin-positive feed in large amounts.
What are some clinical signs that could be associated with ingestion of mycotoxins? What other diseases are rule outs?
Key sign of mycotoxicosis is feed refusal. Also ill-thrift, weight loss, usually all animals in group. Can be immune suppressive, leading to secondary infections. Rule outs are subclinical metabolic, nutritional, or infectious diseases.
How would you test for mycotoxins?
Start by testing whole diet, then feed ingredients. Black light for Aspergillus, on site qualitative tests, full wet chemistry testing
How would you treat and prevent mycotoxin contamination?
Once mycotoxin concentrations known, remove or dilute feed and wait >1 week to observe for improvement. Could try binders. Best approach is to prevent fungal growth in the first place. Prevent storage contamination- harvest, store, silage properly. Use preservatives. Delay grinding, avoid screenings.
Name some common mycotoxins and where they are found/sources.
Aflatoxin (warm climates, high humidity) corn, potatoes, wheat, soy, peanuts, distilled products
Fumonisins (corn especially broken/screenings)
Zearalenone (corn, other grains) ‘pink ear rot’ ‘scab’
Trichothecens (corn)
Ergot (Ryegrass)
Slaframine (clover, clover hay) ‘slobbering factor’
Tremorgens (Grasses, spoiled foods/garbage)
What are the primary effects of aflatoxin? Most susceptible species?
Hepatotoxocitiy, carcinogenesis. Swine most sus. Regulated in milk bc carcinogenic in humans. Young animals more sensitive. Stunted growth. Acute- hemorrhage, bloody diarrhea death. Chronic- icterus, fatty liver, anemia, ascites.
What are the primary effects of fumonisins? Most susceptible species?
Leukoencephalomalacia in horses most sensitive (CNS, death), also swine (porcine pulmonary edema due to heart failure in pigs)
What are the primary effects of Zearalenone? Most susceptible species?
Weak Estrogen. Swine most affected. Vulvar issues, infertility, prolapse.
What are the primary effects of Trichothecens? Most susceptible species?
T2 toxin- immunosuppression in pigs. DON/Vomitoxin! Swine most sus, also small ruminants (vomiting! Rare)
What are the primary effects of Ergot? Most susceptible species?
Extreme vasoconstriction, gangrene/sloughing of extremities. Cattle.
What are the primary effects of Slaframine? Most susceptible species?
Horses ‘slobbering factor’, excessive salivation key sign
What are the primary effects of Tremorgens? Most susceptible species?
CNS overstimulation and tremors. Grazing animals
What type of compound is Monensin? What is it used for?
Polyether Acid Ionophore Antibiotics. Not useful for pathogens, alters rumen biota favorably.
What is the method of action for Monensin?
Alters ion channels in cell walls, heart and skeletal muscle most affected.
What species is monensin approved for use in? Is it always safe in these species?
monensin is approved for cattle, goats, chickens, turkeys, and quail. Still toxic if overdosed.
What species are most susceptible to Monensin toxicity? Clinical signs?
Sensitivity varies with ability to oxidize monensin. Horses very sensitive, cows much less sensitive. Neuro signs, cardiac muscle in horses, skeletal muscle cattle. CHF key sign in horses.
How can you prevent monensin toxicity?
Feed mills cleaning equipment to avoid cross-contamination, avoid totally in small mixed species operations to prevent cross-contamination.
Would you feed cotton products to monogastrics? Why?
No. Gossypol. unbound toxic. Ruminants bind 8x more than monogastrics.
What is gossypol? Who is it toxic to?
Yellow pigment found in cotton plant at highly variable concentrations. Free Gossypol is toxic to all animals- less so to cattle bc bound in rumen. Cotton seed is main concern.
What are the effects/Clinical signs of Gossypol toxicity? Treatment?
Cardiotoxic- cardiac arrhythmia, Congestive heart failure. Yellow fluid. At low level, fertility issues. No specific treatment. Cotton products not usually fed to monogastrics.
What is urea/NPN and why is it fed to cattle?
Nitrogen sources. Rumen microbes make protein from ammonia and carbohydrates, so these are a cheap protein source, but can be toxic.
What are possible issues with feeding urea/NPN to cattle? How would you test for and treat for toxicity associated with them?
When rumen pH becomes high enough, NH4+ converts to NH3 which can diffuse out and overwhelm liver. Results in ammonia-induced encephalopathy, cyanosis, death. Test Ruminal pH, if pH >7.5, treat with cold acetic acid to re-acidify rumen and prevent NH4+ to NH3 and diffusion out of the rumen.
What is salt poisoning/water deprivation? What species does it affect?
Excessive salt in diet, sudden increase in salt, inadequate water. Affects all species, pigs most often due to drinking nipple issues. Sheep least susceptible.
What are the Clinical signs of salt poisoning? Treatment?
CNS signs due to hypernatremia, death from respiratory failure. Acute GI signs. Treat by gradually adding water.
What are the clinical signs of iodine toxicity in cattle?
Lacrimation, epidermal sloughing (dandruff)
How does tall fescue poisoning happen? What are sensitive species and clinical signs?
Type of ergot poisoning, once infected, propagated through seeds, most fescue in US infected. Cattle and horses- grazers. Key signs: ‘summer slump’ in grazing cattle, repro issues in brood mares.
What feed toxin has a specific treatment and what is it?
Urea/NPN. If ruminal pH > 7.5, treat with cold acetic acid.
What herbal supplements are toxic?
Chamomile, garlic, Echinacea, essential oils
List 5 predisposing factors for toxicity in the liver
First-pass effect
Enterohepatic circulation
Unique functions (bile formation/excretion)
Major metabolism site (bioactivation)
Zones affected differently due to blood/oxygen supply (lowest zone 3)
Describe 5 different ways toxicity can lead to liver injury
Hepatocytotoxicity, Fatty liver, Cholestasis, Bile duct dam, Cirrhosis, Vascular, Tumors
What are 4 different types of liver injury and what are the clinical measures of that function?
Hepatocyte injury: ALT↑, AST↑, bilirubin↑
Cholestasis: ALP↑, GGT↑, bilirubin↑, cholesterol↑
Liver mass decreased: urea↓, albumin↓, cholesterol↓, coagulation factors↓
Portal blood flow: ammonia↑, bile acids↑, globulins↑
What are sequelae of chronic liver failure?
GI signs, depression, icterus, reduced milk production, increased sensitivity to toxicity, photosensitization in grazing animals, hepatic encephalopathy
What are the clinical signs and diagnostic abnormalities of acetaminophen toxicity?
CS: BLOOD + LIVER Depression, Tachypnea, Cyanosis, facial edema, chocolate colored blood
Diagnostic Abnormalities: elevated ALT/bilirubin
What is the mechanism of action and specific treatments for acetaminophen?
MOA: Oxidizes Hb to MetHb in dogs and cats only. CYPs convert acetaminophen to NAPQI-> hepatotoxicity.
Specific treatments: Antioxidants (NAC/SAM), Cimetidine in dogs only to block formation of NAPQI, Methylene Blue
What are the clinical signs and diagnostic abnormalities in amanita mushroom toxicity?
CS: GI + LIVER Initial GI phase, latent 12-24 hrs, final phase of liver failure, death
Diagnostic Abnormalities: elevated ALT/bilirubin
What is the mechanism of action and specific treatments for amanita mushrooms?
MOA: Amatoxins bind RNA polymerase, high protein synthesizing cells most sensitive. Phallotoxins and
virotoxins irreversibly polymerize hepatic actin filaments, triggering hepatic cholestasis. VERY TOXIC. enterohepatic circulation.
Specific treatments: NAC/SAM!! Transfusion, Vitamin K.