My mare who had biopsy done and confirmed both Onchocerca as well as Habronema from the biopsy of the neck bump, was itchy on Moxidectin as well. The other mare had edema (as its rare on Moxidectin) but she had it. Both mares got Moxidectin at first.

On reflection, it was probably the pour-on that was being discussed.

Just glancing at studies comparing results on gastrointestinal worms, it seems to be that there is some efficacy in reducing fecal egg counts, but that overall effectiveness is lower due to the lower concentration of ivermectin in pour-ons.

Seeing that more intensive ivermectin administration is needed to knock back the microfilaraie of the neck threadworm (not a gastrointestinal worm), then it could be that a spray-on is even less effective than a pour-on.

I believe someone brought it up in the comments after the first article, The Disturbing Truth About… and I seem to remember somebody expressing a concern about DMSO content, the skin thicknesses being very different in cattle. What do you see as the advantages of using a spray?

That’s interesting, isn’t it? Obviously if the Auranofin was at trial stage last year, it’s some way off being licensed for medical or veterinary use. If only the equine issue would receive greater recognition, then there might be a greater push for that (ie, a market exists).

I can picture a trial in the use of doxycycline in equines, though! I must finish that lit review… unfortunately my research area is different.

Great information, thank you!

Also it appears that Auranofin a human arthritis drug, can kill half of the adult worms with each dose.
http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003534

Thanks Claire! I think there is definitely regional variation in the culicoides and also in the areas of the horse that they bite. I still stand by the questions asked in this post after having done further reading in the literature on the subjects, much of which relates to sweet/Queensland/summer itch.

As for NTW not being present in a region, well, I’d have presumed it wasn’t prevalent in the UK, yet a clutch of owners have come forward reporting positive repsonses to ivermectin in itchy horses following the floods of recent years. There must be others ‘hidden’ amongst the itching horse population, but with less severe symptoms.

As for the extent of problematic NTW in more temperate areas, I imagine it occurs where three factors combine: enough horses with NTW to ‘seed’ the population, a large and prevalent number of culidoid vectors, and enough carrier horses to throw up the minority of cases with a severe, highly visible response.

Meanwhile, ivermectin remains a quick, easy and cheap way to identify or eliminate NTW in the case of severely itching horses.