Change in behaviour

Hi there,  we have a 7 year old boy who  although nervous around strangers and untouchable by them, he is a completely normal dog with myself and my partner and we have had home for 5 years.  For the last 6 - 8 weeks he has been reactive when either myself of my partner touch him.  No specific area, he will show his teeth and give us a light snap.  We got X-rays, examination and blood work down which was all fine.  The questions remains as to what is causing his change in behaviour towards us and could it be beneficial to get a CT scan to check for neurological issues.   I feel that my vet may have put it down to behaviourial issues because of how terrified of him he was and he had to get sedated,  which was horrendous for him as he was really struggling and has to be muzzled,   just to be examined.   I’m happy to work with a behaviourist but I feel this may need further investigation. many thanks

Hello and I'm sorry - this sounds like a distressing change.  A veterinary qualified behaviourist would be my immediate recommendation too - and sooner, rather than later.  However while that is pending, have you and your vet considered pain? - as many animals reported to be suddenly aggressive are found to be suffering with pancreatitis, arthritis or similar, even if it is not externally obvious.  Many of these pets are painful before they stop eating or start vomiting and while examining a dog usually shows painful areas, it is difficult to examine a hyper-stimulated dog that is unable to relax in the vets, for signs of pain.  Nor do these show on most routine blood panels.  However sometimes, an effective trial pain-killer over a few days can make a big difference.  My belief is that MRI findings come up occasionally in such cases (e.g. if there were to be a sizable tumour), but less commonly.  I wonder whether there is someone - perhaps a pain specialist - that your vet can talk the case over with?