We've got blackthorn everywhere down here,had a thorn go in the centre of the palm of my hand when out ferreting,but just pulled out what I could see and rubbed it a bit.It hurt like feck for about two weeks,and then went off,but,a week later it went septic and burst,and,out came the tip section of the thorn......OW!
And it is the powder on the thorn that makes it go nasty that's for sure. She will be ok though,and running around again soon.