I know that ZNO receives it's lowest selling price selling to...

I know that ZNO receives it's lowest selling price selling to Animal Health market around $11 per litre, the retail price via the online store is $50 per litre.
So the margins should be very good for AHX, the average margin for ZNO across all channels is around 67% with retail in excess of 75%.

You have highlighted the biggest issue with AHX it's debr which has been accumulated via acquisitions buying vetinary practices etc.
It's these acquisitions that should be put under the spotlight as an analysis of past performance.
I would be quite happy if they didn't make anymore acquisitions & reduced debt rather than continued paying dividends.

As for my investment thesis it's all about the transformation of AHX re ZNO which I've held for over 2 years. The Animal Health application of ZNO products is potentially massive & IMO an industry changer due to the productivity gains achieved as well as the virus protection. I can see AHX easily do $10m in ZNO product sales over the next 12 months, flowing through at potentially 50% to the bottom line.
I'm regularly in contact with the ZNO CEO & he's very impressed with AHX which is why they've been given additional markets in Asia, I expect this to continue if the volume is delivered. USA is however the big, key market where they are terrified of getting ASF.

As for whether ZNO is a better investment now vs AHX, I think a lot is priced in to ZNO where as practically none of ZNO product growth is factored into AHX.