Hi i got jem the dogmatic headcollar and it has worked great

but when a car passes she still goes mad, but the situation is alot safer now i have the dogmatic but how can i stop her wanting to chase them? iv tried all sorts of treats but she just isnt iterested in them, she is so fixated sp? i just cant get through to her, she wont listen to a word i say

iv tried turning her away from them but that doesnt work either coz she still manages to turn to the car again. can someone think of any thing else i can try?