I have two Sibes and never let them off lead when excercising. I was curious to know which other breeds you consider to be "unsafe", that is unreliable to the point of desertion when off lead. Most of the spitz type I would guess, any others?
Lynn

My Elkhounds and many others I know are fine off lead, as are most Keeshonds, Samoyeds, Buhunds etc.  Yes they are more of a just a minute Mum type of thing, but not bad.  I think the main n ot off lead spitz are the sled dogs and those of a very dog dominant nature.

Sighthounds can be difficult to let off lead as they are atracted to moving objects and when in full flight can be in trouble even before the owner can get a command out.

Terriers can be difficult in Rabbit country, and have been known to go to Ground, but most are still let off lead in appropriate places.

Any breed with an incompetent owner!