Ok.  Following on from my 'other causes of joint pain' thread I've had a rethink, pondered Remy's history and known problems and I have a theory about why he's responding so poorly to everything I'm trying for his arthritis.

He's been hypothyroid from around 2yrs old; 3yrs to diagnosis and a further 3yrs before he was on a treatment that worked (soloxine for 3yrs which makes him much worse, he is now on T3-only therapy).  He has a major B12 deficiency due to the 6yrs of untreated hypothyroidism; not tested as yet but symptoms fit it and he responded 100% to supplements almost overnight.  That's being tested soon to confirm, along with folate (he's been off supps for a fair while, and is symptomatic again, so he'll be tested before he goes back on them).

So with what I know about the vit/mins and thyroid connection, I'm thinking that there may be other deficiencies at play here.  Firstly affecting the thyroid problem directly - certain deficiencies inhibit the cells' ability to utilise the hormones causing symptoms, one of which in people is FM - which would be one reason for him not responding to anti-inflammatories, as it would be joint pain caused by the hormonal side rather than arthritis (although he does have this, hence some response).

Secondly affecting the absorption itself and this is where this thread comes in (yep, I'm getting to a point!).  What I'm wondering is if anyone has any knowledge or experience of drug efficacy being affected by poor absorption for whatever reason - either the vit/min deficiencies I'm looking at at the moment, or through other mechanisms: Lindsay has suggested possibly low stomach acid, which does tend to accompany low thyroid in people and while I don't think he has trouble with this it is something I'm keeping in mind (as I have it myself and you wouldn't know it, so I might just not be seeing external symptoms with him).

He did have almost constant gut problems for his first 3yrs - so many times I thought he was going into torsion overnight because he would be in such pain, then he would start with vomiting and diarrhoea all night.  I lost count how often it happened - in the end he went on raw feeding for 3 months and it sort of 'reset' his system, and I've not had a day's trouble since.  He'll be 10 on the 1st (OMG my puppy is nearly 10 :-().