I would not use cotton thread in the bobbin. When a dog gets wet .. the underside of the collar and the area at the chest are the last to dry. This could result in the cotton thread rotting or degrading. For a bobbin thread I would use 100 percent polyester thread. As for securing the stitches the a shorter length helps but I back tack going several stitches reverse and several forward three or four times... and sometimes for an inch . Monofiliment thread is really slippery stuff.. it just does not "secure" the way regular thread will.
Last edited by QuiltnNan; 07-11-2013 at 03:32 AM.