Any Ideas? Raised liver enzymes

My boy has been back in walk work for a week now. The last test on 14th Feb showed slightly raised enzymes but Bile was ok. Vet said that he was so bright and fit and FAT that he could start some work and test again in 6-8 weeks. No idea of the cause but the antibiotics were definately helpful as we left this out of the second course of drugs and didn't improve much at all. I've also been giving him the Hilton Herbs hepaphyte gold which is only £20 and lasts about 6 weeks.
 
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