ECG alterations and changes in biochemical parameters associated with experimental salinomycin toxicosis in sheep

Document Type: Full paper (Original article)

Authors

1 Ph.D. Student in Pharmacology, Department of Basic Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

2 Department of Basic Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

3 Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

4 Graduated from School of Veterinary Medicine, Shiraz University, Shiraz, Iran

5 Graduated from School of Veterinary Medicine, Shiraz University, Shiraz, Iran; Department of Basic Sciences, College of Veterinary Medicine, Kazerun Branch, Islamic Azad University, Kazerun, Iran

Abstract

Salinomycin is a monocarboxylic polyether ionophore with antimicrobial properties. It is a dietary
additive used as a growth promoter for ruminants and as a coccidiostat in chickens. The mechanism of action
of ionophores at the cellular level is to selectively bind certain ions creating intra and extracellular
biochemical disturbances. Clinical signs of ionophore intoxication are non specific and similar in all species
and include tachycardia, muscle tremor, restlessness, loss of appetite, incoordination, muscular weakness and continual panting. The present study was conducted to determine the changes in ECG parameters and
possible arrhythmias and their types due to experimental salinomycin toxicosis in sheep. Acute toxicity with
the ionophore (0.5 mg/kg; intravenously) was induced in 6 mixed breed female sheep. A corresponding
volume of sterile saline was intravenously injected in each control sheep (n=6). Blood samples were
collected before and at various time intervals after the administration of either salinomycin or saline
solutions. Following centrifugation, serum biochemical parameters (ALT, AST, CK, LDH and total protein)
were measured using conventional laboratory methods. In both groups, the heart sounds of sheep were
carefully monitored and the electrocardiogram (ECG) was recorded. Salinomycin caused a significant
(P<0.05) increase in the levels of ALT, AST, LDH and CK in the experimental animals. The mean heart rate
in the control group was significantly lower than that in the experimental sheep. Numerous arrhythmias such
as sinus tachycardia (11 cases), ventricular premature contraction (2 cases) and T-wave inversion (3 cases)
were recorded in the experimental sheep. Acute salinomycin intoxication seems to cause numerous
arrhythmias in sheep which might be due to the pathological effect of the ionophore on the myocardium.

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