Any chance you could spritz his tail with that stuff they use to keep animals from gnawing at bandages? The vet should have some handy.
Many years ago, our cat had a spot on his side that he would lick compulsively to the point where it would get raw and oozing. We spent a year with repeated steroid injections (would relieve the itch or whatever it was, so the lesion would scab over, but then he’d go at it again), surgery to remove a chunk of skin as it was looking necrotic (steel prongs holding it shut - he went after it the minute the spikes were removed), and many months of wearing an e-collar 24/7.
What finally did the job? A spritz of the stuff right on that spot on his fur. He licked it once and started foaming at the mouth (we found gobs of petrified slobber days later).
He tried again the next morning… same thing happened.
As far as we could tell, he never tried it again.
