Oesophageal Groove closure
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The oesophageal groove reflex is well developed in suckling neonates but becomes less reliable in older animals.
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Bypassing the ruminoreticulum can have several advantages.
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Drugs administered directly into the ruminoreticulum are absorbed very slowly when compared with abomasal delivery.
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Moreover drugs may be degraded by ruminal microflora (eg: chloramphenicol and digitalis glycoside) or the drugs may be harmful to the beneficial microbes (eg; tetracyclines, penicillin and sulfonamides).
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Oral administration of medicaments intended for the local intestinal effect (eg: purgatives, antidiarrhoeals, contrast media and some anthelmintics) should be preceded by administration of an appropriate of salt solution to close the reticular groove to avoid ruminoreticular dispersion.
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5% copper sulphate, 5% zinc sulphate, 10% sodium bicarbonate or 10% sodium sulphate can be administered at doses of 60ml to cattle to bring about closure of oesophageal groove.
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1-2% copper sulphate is useful in sheep. Onset of reflex response takes about 5-10seconds and the groove may remain closed for up to 60 seconds.
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Suckling is a strong stimulus for this reflex even in adults. It is best to allow sick calves and lambs to drink medicated milk from a nipple to assure abomasal delivery and rapid absorption.
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Administration of liquid medication to ruminants orally may result in spontaneous closure of the reticular groove in a certain number of calves which results in an complete or partial rumino reticular by pass.
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When stimulated, buccal and pharyngeal receptors activate a vagal reflex that closes the groove withing 2-5 seconds: effects last for 60 seconds.
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Milk , sodium bicarbonate (10% to calves) or copper sulphate (5% to calves, 2% to lambs) but not water may be used to induce esophageal groove closure.
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Last modified: Wednesday, 25 April 2012, 10:35 AM