I'm having trouble with both Doppler and Virga pulling when they're going for walks. Doppler doesn't pull too bad. I think I just need to reinforce proper walking with him again. But Virga pulls so hard she chokes herself. Does anybody have any suggestions on whether using a head collar like Gentle Leader or Halti, a regular training collar, or halters would be better for my dogs? I hate to hear and see Virga choking herself and Doppler is so big he could pull me off my feet if he really wanted to. Any suggestions would be appreciated.