Thank you for your replys.
Let me explain.
I drive a pair of 18yo shetland geldings (half brothers). Ive owned them 9 months. At home they are perfect.
The twice we have been to driving shows we have had issues. They come later in the day. Only 1 has a problem.
I get disgraceful behaviour rearing, bucking, growling and attempting to bolt. I have on both occasions pushed him through it. Other shettie just looks on with disgust.
Both have been driving years and previous owner says this behaviour is totally new.
I do accept it could be me.
On both occasions after going back to the lorry, unharnessing..... Naughty pony has uninated for England. Gallons of it. Then hes back to normal.
They are fit, drive regularly, forward going, live out chappies.
Naughty pony has been a bit strumbly recently, so hes on tumeric which has really helped. His coat has not departed as well as his brothers.
He is drinking more, urinating gallons, almost like it comes as a suprise often straight after a driving session. Cold hoofs no pulse. No fatty deposits, but slightly dull eyes. I am getting the vet out, but I was interested in others experiences.
I found a USA blog site that almost perfectly described his behaviour.
Oh if he wees in the lorry en route, he behaves fine too.