So I tried it after getting all caught up in John's blog about it. I'm in nowhere near his situation when he started it - my PC has never left the gland in 11 years, and I've had four-count'em-four hifus in that time, each triggered by biopsy. IOW, hifu has never killed all the cancer (though it killed my sex life after so many treatments - the nerve bundles can take only so much boiling).
Last November my PSA was 0.9 - about the usual. But by April it had doubled to 1.8, and in May in was 2.27, so of course I was alarmed. No biopsy yet - I'm pushing for MRI-guided on the advice of my doctors, but the MRI-guided biopsy doctor, after looking at my MRI (admittedly showing kind of a messed-up prostate) said I didn't meet the "criteria," which are still a mystery to me (I'm working on this). I haven't decided what to do about the revived cancer, though I'm leaning toward another hifu (and not only because we get to go to France for it).
Anyway, after May's result, I bought some Panacur on Amazon - two 3-packet boxes. I got the 4-gram packets for big dogs since I am a big dog. Took them two successive weekends. I had another PSA test this week, one month after taking the Panacur. The PSA had dropped to 1.84. Is that a 19% drop? I'm bad at math.
I have no idea if the Panacur did that - PSA can go up and down for no apparent reason, but I'd done nothing myself to make it go up or down. But in my case anyway, the PSA has always varied by a tenth of a point - this time it was 4 tenths. Maybe it was the lab, maybe it was natural variation, maybe it was the Panacur.
So I think I'll take it again, and take it for longer this time, like a month until I have another PSA test. And then decide what to do about the cancer, if anything.