Girthy horse...

[throughtheforest]

After a new saddle (thorn saddle pad with acavallo pad and saddle cloth), girth (wintec weight distribution, anatomical girth for forward girth groove) , my horse has become girthy. Notably this started after my instructor came the other week and I noticed she seemed to do the girth up tighter and faster more than I do. Ever since he has now started biting whilst being girthed up. No other symptoms of lameness, ulcers etc, but his face does seem to drop when I start tacking him up. He did however, show no reaction when I girthed up out on the hack...
Is this a response to fear of pain, or pain itself? Before he was in this saddle pad the other saddle was pinching him and was uncomfortable.
Where would you start with this? I am thinking of starting with assessing his pectoral muscle and also distracting him whilst being girthed.

 

[Palindrome]

It sounds pretty clear that your new treeless saddle or girth are uncomfortable for him. I would start by checking if his back is sore (the vet can do that if you are not sure how to do it) and then try a well fitted treed saddle.