The human dog had an intrinsic need to be complete, so just as having his paws, his collar the need to doggification keeps him striving on for complete transformation. First it was ok just to have the security of the collar, then each component helps as a further catalyst in the transformation. The need for a dog trail is significant, as there is a whole load of expression that a tail affords. Even dogs with no tails wag their butt when happy.
The first stage is to have a butt plug fitted into your pup. For the most part this is good starting point, but it is just like a gag under the muzzle. It makes the slave free good and controlled by his Master, but dogs don't have anything up their butts in real life. Another option is to have a tail hanging from a harness. There have even been the use of piercings as attachment points. This is ok until you imagine standing ok it as you are moving. It is bad enough having a butt plug tugged out of your butt, but what off a piercing torn out.
When the doghouse started there a handful of people into this scene, but it
acted as a catalyst being like minded people together, with a common need.
This is something that any supplier can understand. Imagination drove
product development, some things worked and others less so. Now one good
design with is being mass produced is a latex bung (like a egg/door knob)
that fits into the butt and has a flexible latex tail that is very waggable.