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31 Cards in this Set
- Front
- Back
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What are 2 primary ionophores?
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Monensin
Lasalocid |
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What is monensin used for?
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Increases weight gain 10%, decreases incidence acute bovine pulmonary emphysema and edema
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What 3 animals is lasolocid used in?
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Poultry (coccidiostat)
Cattle Sheep |
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What are ionophores?
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Monovalent polyether antibiotics
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What produces ionophores?
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Fermentation by various Streptomyces fungi
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Under non-toxic use, what is the mode of action of ionophores?
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Act by altering microflora population of the rumen
-meant to stay in GI tract, not meant to be absorbed systemically -ionophores transport ions across biological membranes |
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What are the 3 conditions conducive to ionophore poisoning?
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1) Exposure of therapeutic doses for food animals (cattle) to susceptible species i.e. horses
2) Feeding poultry litter 3) Concurrent use of some drugs will decrease therapeutic effect 10 fold & increase toxicity 8 fold |
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What is the mode of action of ionophore toxicity?
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affects excitable membranes: cardiac and skeletal muscle
-forms lipid soluble complexes with mono and divalent cations facilitating transport of them across the membrane along diffusion gradient |
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**How long does it take for the onset of clinical signs due to ionophore toxicity?
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Latency period (and signs) varies depending on species, age, diet, ionophore and most importantly dose
-1-2 hours (death with no signs) -up to 2-3 weeks -overall average 12-72 hours |
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What is the most common clinical manifestation of ionophore toxicity?
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Partial to complete feed aversion (to that product)
-animals will eat other foods, weakness, ataxia, dyspnea, tachycardia and diarrhea |
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What muscles are affected by ionophore toxicity?
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Cardiac OR skeletal
-may affect one or the other or both depending on species |
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What muscle is predominantly affected in horses with ionophore toxicity?
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Cardiac
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What are the clinical signs of ionophore toxicity in horses?
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-Single high lethal ingestion- colic, ataxia, recumbency, tachycardia, arrhythmia- death < 48 h
-Non acute single lethal dose- cardiac, pleural edema, ascites, respiraotry dyspnea, arterial hypotension- death 10 d -sudden death- acute cardiac failure |
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What muscle is affected by ionophore toxicity in cattle?
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Cardiac
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What muscle is affected by ionophore toxicity in poultry?
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Cardiac & skeletal
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What are the clinical signs of ionophore toxicity in poultry?
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-chicken/turkey knockdown syndrome
-reduced fertility and hatchability rates -feed refusal |
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What muscle is affected by ionophore toxicity in sheep, swine, cats and dogs?
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Skeletal muscle
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What are the clinical signs of ionophore toxicity in sheep, swine, dog and cats?
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Feed refusal, depression, stiffness, ascending muscle weakness, paresis/paralysis and recumbency
Death usually from respiratory failure |
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What is the toxic dose of ionophores?
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Toxicosis may result from a single dose or can occur after daily low level exposures (mixing error)
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What animal is most susceptible to ionophore toxicity?
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Horses
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What is the most consistent clinical pathology related to ionophore toxicity?
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Increased bilirubin
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What are the 2 primary lesions you will see in horse, cattle or poultry that died from ionophore toxicity?
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1) Pericardial and peritoneal effusions
2) Pericardial and epicardial hemorrhages |
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*Why is it so important to take multiple samples when trying to diagnose ionophore toxicity via histopathology?
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Lesions may have a *focal distribution so multiple sampling is a must
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What are the 5 organs affected by ionophore toxicity?
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1) Heart
-pale microfibers, loss of fiber striation, multifocal vacuolar degeneration 2) Skeletal muscle -severe degeneration/ necrosis type I muscle fibers 3) Kidney -acute tubular necrosis 4) Liver -Centrilobular necrosis, mild fibrosis, congestion 5) Pancreas -zymogen granule depletion |
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What are the 2 primary ways to diagnose ionophore toxicity?
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1) History of change of feed
2) Feed analysis |
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How do you treat ionophore toxicity?
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No specific treatment
Primarily supportive care |
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What is the prognosis of the cardiac form of ionophore toxicity?
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Poor
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What is the prognosis of the skeletal muscle form of ionophore toxicity?
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Dependent upon use of the animal
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How do you treat ionophore toxicity?
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No specific treatment
Primarily supportive care |
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What is the prognosis of the cardiac form of ionophore toxicity?
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Poor
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What is the prognosis of the skeletal muscle form of ionophore toxicity?
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Dependent upon use of the animal
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