Oxalate poisoning
Plants contaning oxalates
Sources of poisoning
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Oxalate poisoning in livestock primarily results from ingestions of large quantities of oxalate containing plants.
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Oxalate containing plants are palatable and frequently form bulk of ruminant’s ration.
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For causing toxicity, the plants should contain more than 10% oxalic acid on dry-weight basis. The form in which oxalate is present in the plant may be of importance in terms of toxicity, that is whether it exists mainly as acid oxalate (e.g. in Oxalis sp. Rumex sp.) or oxalate ion (e.g. in certain Chenopodiacae).
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Some of the common oxalate containing plants are listed in Table.
Table: Some of the important oxalate containing plants
Amaranthus retroflexus
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Rheum rhaponticum
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Atriplex sp.
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Rumex sp.
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Beta vulgaris (beet)
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Sarcpbatis vermicularis (Grease wood)
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Brassica hyssopifolia
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Spinacia aleracea (Spinach)
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Calandrinia sp.
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Salsola kali sp.
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Chenopodium album
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Setaria sphacelata
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Halogeton glomeratus
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Threlkeldia proceriflora
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Oxalis sp.
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Trianthema sp.
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Portulaca sp.
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Mechanism of toxicity
Clinical signs
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Dullness, lowering of the head, loss of appetite and remaining isolated from the herd are initial evidences of oxalate poisoning seen after 4 hours of feeding oxalates-rich plants.
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These observations are followed by excessive salivation with frothing, progressive incoorrdination and coma with deep irregular respiration. Convulsive episodes may also be noted.
Post-mortem lesions
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Lungs may be filled with dark-red or purplish coloured blood as most of the deaths in oxalate poisoning are associated with asphyxia.
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Petechiael haemorrhages and cyanosis may be seen at various location.
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Crystalline masses may be observed in renal tubules, with a concentration in the cortices.
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Microscopic examination of kidneys may reveal presence of calcium oxalate crystals, ruptured tubules and degenerative changes.
Diagnosis
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Last modified: Friday, 23 March 2012, 9:00 AM