Hi Gerry,
bold choice I must say, and unfortunately a lot of ensueing problems!
The leashes would be leather, not string, as string does not allow for a firm grip (necessary when you have to control powerful dogs). Tips for material have been given and are absolutely satisfactory.
The dogs are the main weak point here ("bold choice", remember). Animals are hard to paint anyway, and I've yet to find a decent dog model in this scale (the right side dog looks more like a dingo than a gs). So the end result here is unfortunately poor.
Dogs' inner ears are not pink!
Colours within the coat are not so clearly divided like this. And these dogs are rather long haired. Try to use that to your advantage! Paint them in (rather) thick oil paint and you have the possibility to "model" strands of hair in the paint by simply using a rather crude brush. I usually do that with my horses, especially for a "campaign" look.
You have to be careful and check on the "flow" or "direction" of the hair within the coat. Animals do not forgive faults, hence the "bold choice"!
(And a quick Google search for "deutscher Schäferhund" produced a wealth of photos, showing also that gs are almost constantly panting when in action, i.e. tongues out!!!)
Sorry for sounding harsh, but I just want to help avoiding similar faults that spoil the otherwise great job in the future.
Cheers
Romain