The only time my dogs were walked in the street is the two minute walk it takes to get from our house to the fields so it isn't like they really had to hold themselves. Also, they could do it in the run beforehand if they were busting. Also, dogs kept indoors have to hold themselves all the time.
Being creatures of habit, they preferred to wait until they got to their favoured spots down the fields and then they'd do their business.
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