Development of a toxin-binding agent as a treatment for tunicaminyluracil toxicity: protection against tunicamycin poisoning of sheep

Objective To assess the ability of certain derivatives of beta-cyclodextrin to treat sheep affected by tunicaminyluracil toxicity, using tunicamycin poisoning as a model system.
Design Controlled treatment trial.
Animals One hundred and sixty Merino wethers were used in the studies.
Procedure Groups of sheep were experimentally poisoned with tunicamycin. Derivatives of beta-cyclodextrin, with or without magnesium sulphate and magnesium gluconate, were administered to treatment groups daily for 2 to 3 days. Treatment groups were compared with untreated groups in terms of survival.
Results A significant increase in survival was observed following treatment of tunicamycin-affected sheep with hydroxypropyl-beta-cyclodextrin (HPb -CD) and magnesium sulphate in solution (P < 0.05). In subsequent trials, formula tion of the cyclodextrin in the form of a magnesium gluconate gel suspension demonstrated significant protection (P < 0.01) and was equally as effective as the cyclodextrin in solution, but required half the frequency of administration, even when the treatment was not commenced until 24 h after the final toxin dose. Beta-cyclodextrin-epichlorohydrin copolymer also improved the survival rate. After toxin administration, the sheep lost significantly less weight if treatment with HPb -CD was commenced early (P < 0.001).
Conclusion Protection studies using these two beta-cyclodextrin derivatives suggest that they may be effective in increasing the survival of sheep poisoned by tunicamycin and warrant further testing in field outbreaks of annual ryegrass toxicity.