I have 2 dogs, brothers, brought up together and now 5. Dachshund chihuahua X. One of them occasionally nips men. If man comes to the house I pick him up until he's stopped barking and then distract him with treats. He's then OK although a workman recently had his finger bit when he reached out to pat him as I was holding dog. Today out for a walk with DH he chased and nipped a runner leaving a red mark and a hole in runners leggings. Other people had passed perfectly OK. He just seems to take a dislike to some. Is a muzzle the only answer?