This is a massively long story going back a year. I have a 2 year old border terrier with digestion issues - he was provisionally diagnosed with IBD when the vomiting and pooping bloody mucus first occurred at 11 months old, and was transitioned to a hydrolysed soya diet when he appeared to react violently to all meat proteins. He's had fecal tests (3 infections, all cleared with treatment), blood tests (high folates and low vit B, seemingly resolved since) - it took 6 months to settle him on a meat-free diet and get some weight on him, then we tried to challenge him with other proteins again and he vomited everything out within 12 hours of trialling it. So we stick to 100% meat free food and treats, and he no longer vomits daily or has diarrhoea.
In July and October) he had flare ups due to stress which caused rapid weight loss followed by an anal gland issue - we managed to get weight back on him, but he started scooting. Since July he's had his anal glands emptied 6 or 7 times - but the last few times the vet has remarked that there wasn't much in there, and they're not full, impacted or infected - just very enlarged and blocking his little bum by a third.
He's started an odd behavioural habit of anxiously sniffing every surface then sniffing round at himself, and he's often quiet and distracted - not the happy, bouncy daft dog he's always been. He scoots, snatches at his tail and hind legs, and paws at his face. He's sometimes reluctant to go for a walk. He shows no discomfort or straining when pooping though, all that is normal.
The vet knows all of the above and has given him 3 lots of steroids since October, but he's fine for 24 hrs and back to his old self, before he reverts to itching/scooting/being afraid of his back end and absently sniffing again before the course is even finished.
He has no visible skin irritation, he doesn't have fleas or worms (all regularly treated/prevented). He has another follow up on Friday and I'd like to go in with some differentials!
Any ideas? If the steroids aren't helping then presumably it's not an allergy/inflammation problem?