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OJVRTM
Online Journal of Veterinary Research©
Volume 1:20-26,
1997
Experimental yellow-wood (Terminalia
oblongata) intoxication in sheep
1Filippich LJ, 2Cao
GR, 3Alsalami MT, 4English PB.
aSchool of Veterinary Science, The University of
Queensland, Queensland 4072, Australia, b The Northwestern
Agricultural University, Yangling, Shaanxi, Peoples
Republic of China,c Royal North
Shore Hospital, Department of Anatomical Pathology, St. Leonards,
New South Wales 2065, Australia, 4Deceased
ABSTRACT
Filippich LJ, Cao
GR, Alsalami MT, English PB., Experimental
yellow-wood (Terminalia oblongata) intoxication in sheep, Online J Vet Res
1(3):23-42, 1997.
Authors describe pathophysiology of chronic Terminalia oblongata (yellow-wood) intoxication in sheep.
Yellow-wood leaf was air-dried, hammer milled and administered orally, as a
drench, or intraruminally to sheep at various dose
rates over several weeks. Chronic administration of
yellow-wood leaf lead to reduced ruminal movements, inappetence
or anorexia, body weight loss, reduced water intake and urine output. A
normocytic, normochronic anaemia
occurred in all sheep and blood gas and acid-base balance moved towards a
metabolic acidosis as the study progressed. Plasma aspartate aminotransferase
activity fluctuated while plasma alkaline phosphatase activity remained normal,
except in one sheep which developed clinical jaundice. Plasma total protein
levels remained normal or rose while plasma sodium concentration remained
normal. Plasma potassium levels remained normal but decreased in one sheep to
2.8 mmol/l. Plasma urea and creatinine levels
remained normal throughout the study and changes in plasma urea reflected
changes in feed and water intake. Towards the end of the chronic yellow-wood
intoxication study, renal mass in the sheep was reduced to 50% of normal by
unilateral renal infarction so that the effect of chronic yellow-wood
intoxication could be assessed in sheep with reduced renal function. After several
more weeks of yellow-wood dosing, some of the sheep with reduced renal function
showed neurological signs similar to those previously reported to occur in the
field. However, none of the sheep showed a decrease in renal concentrating
ability that could be attributed to chronic intoxication although one sheep
went into acute renal failure. Evidence is presented to show that some sheep,
not previously exposed to yellow-wood leaf, may have some degree of natural
resistance to yellow-wood intoxication and that with continued exposure sheep
can develop a tolerance to the yellow-wood toxin.
KEY WORDS:
Terminalia, yellow-wood, tannins, sheep, intoxication.