Ionophore Toxicosis Flashcards by Jen Whitmore

What can ionophores be used for in cattle, poultry and goats?

Anticoccidial

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What can ionophores also be used for in cattle?

Growth promoter feed additive

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Which ionophore is approved to improve efficiency of milf production in dairy cattle in the US?

Monensin

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What are 2 things ionophores can reduce in ruminants?

Bloat

- Rumen acidosis

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What can ionophores prevent in cattle?

Tryptophan-induced atypical bovine pulmonary emphysema

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What are 6 examples of ionophores?

Monensin
Lasalocid
Salinomycin
Narasin
Semduramicin sodium
Laidlomycin propionate potassium

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Are ionophores soluble in water?
In organic solvents?
Oils?

Slightly
Yes
Yes

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How do ionophores cross cell membranes?

Form lipid-soluble complexes with polar cations (Na+, K+, Ca2+, Mg2+)

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Which is the most commonly found ionophore?

Monensin

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What is the most common source of ionophore toxicity in chickens, cattle and swine?

Eating feeds that contain more than the recommended levels of ionophores.

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What is the most common source of ionophore toxicity in horses, sheep and dogs?

Eating feeds with added ionophores, accidentally or intentionally.

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Which animals are susceptible to ionophore toxicity?

All animals

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Which species is the most sensitive to ionophore toxicosis?
Which is intermediate?
Which is least?

Most: horses
Intermediate: cattle
Least: poultry

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Concurrent administration of what 5 drugs can increase the toxicosis of ionophores?

Tiamulin
Chloramphenicol
Erythromycin
Sulfonamides
Cardiac glycosides

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Ruminants absorb about 50% but monogastric animals absorb most of which ionophore?

Monensin

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What type of blood and tissue levels are seen with monensin?

Relatively small

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Does monensin accumulate in tissues of animals when given in high doses?

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Where and how are ionophores metabolized?

Excreted?

Rapidly by P-450 oxidative demethylation enzymes in the liver
Mainly in bile

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Why are ionophores metabolized more slowly in horses compared to other species?

Horses have the lowest oxidative demethylase levels compared to other domestic species.

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What do ionophores disrupt?

Transmembrane electrochemical gradients

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What are the main targets of ionophores?

What are 3 examples of these targets?

Mitochondria of highly energetic tissues

- Myocardium, skeletal muscles, kidney

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What does the influx of the sodium-ionophore complex cause?

Increasing intracellular sodium accompanied by increasing intracellular calcium

Does ionophore toxicosis lead to increased or decreased cytoplasmic calcium levels?

Increased

Why does cell death occur with ionophore toxicosis?

Disrupting of homeostatic mechanisms

Catecholamine release from ionophore toxicosis results in what?

Oxidation products and free radicals causing sarcolemmal membrane damage.

What are 4 examples of excitable cell types where disruption of ion concentrations resulting from ionophore toxicosis can alter their functions?

- Neurons - Myocardium - Skeletal muscles - Smooth muscles

Is the onset of ionophore toxicosis in horses slow or rapid?

Rapid

Anorexia, profuse sweating, colic, depression, incoordination, hyperventilation, tachycardia, tachyarrythmias, prostration and death can result from what type of toxicosis in horses?

Ionophore toxicosis

Which of the following is not a sign of ionophore toxicosis in cattle: anorexia, diarrhea, depression, tachycardia, labored breathing, ataxia, prostration, death

Tachycardia

What are 2 clinical signs of ionophore toxicosis specific to poultry?

- Resting on the knees with wings and leg directed outward | - Decreased egg production

Ataxia, muscle weakness of hind limbs, respiratory paralysis, dysuria, constipation and depression are clinical signs of ionophore toxicosis seen in which species?

Dogs

What is main lesion seen in horses with ionophore toxicosis? | Another lesion that can be seen?

- Cardiac muscle lesions | - Skeletal muscle lesions

Skeletal muscle lesions are the main lesions seen with ionophore toxicosis in what 3 species?

- Sheep - Swine - Dogs

Both skeletal and cardiac muscle lesions are seen with which 2 species?

- Cattle | - Poultry

What do chemical analysis methods or ionophores detect?

Ppb levels

What is the best type of sample for ionophore detection? | What are 3 other possibilities for samples?

- Feed | - GI contents, liver, feces

With ionophore toxicosis, what 4 enzymes can have elevated levels?

- Creatine phosphokinase (CPK) - Aspartate transaminase (AST) - Lactic dehydrogenase (LDH) - Alkaline phosphatase ( ALP)

What 2 electrolyte levels are decrease during the first 12 hours of ionophore toxicosis? What electrolyte level has no change?

- Ca2+, K+ | - Na+

What happens to PCV during ionophore toxicosis?

Increases

Diagnosis of ionophore toxicosis is made with what 4 elements?

- History (feed-related problem) - Clinical signs - Lesions - Lab diagnosis

What does a general differential diagnosis for ionophore toxicosis include?

Other myopathy and neuropathy conditions

What are 3 differential diagnoses are included with horses? | One with cattle?

- Horses: colic, blister beetle ingestion (cantharidin toxicosis), azoturia - Cattle: Vit E/selenium deficiency

What are 3 plants that can cause skeletal muscle signs similar to ionophore toxicosis?

- Coffee senna - Coyotillo - White snakeroot

What are 4 plants that can cause cardiotoxic signs similar to ionophore toxicosis?

- Oleander - Taxus spp. - Milkweed - Vetch

Nutritional myopathy, coffee senna toxicosis, botulism, Na+-water deprivation toxicosis, mycotoxicosis, round-heart disease and downer syndrome (viral arthritis) are all differential diagnoses of ionophore toxicosis for which species?

Poultry

Is there any specific antidote for ionophore toxicosis?

What should be done right away with ionophore toxicosis?

Remove medicated feed

What are 3 things that can be given to decrease the absorption of ionophores?

- Activated charcoal - Mineral oil - Saline cathartics

What are 2 things that can be given to correct hypovolemia and support cardiovascular and renal functions with ionophore toxicosis?

- IV fluid | - Electrolyte therapy

How long should cardiac function be monitored with ionophore toxicosis?

Several months

T/F: It is ok for horses to resume normal work 2 weeks after ionophore toxicosis.

False - Horses should not be ridden or stressed for several months.

What may decrease muscle damage from ionophore toxicosis, especially in cattle and swine?

Vitamin E/selenium

Horses that survive ionophore toxicosis may suffer from what?

Myocardial scarring and necrosis

Will horses that survive ionophore toxicosis always fully recover?

No, horses may not reach previous performance levels.