The myriad signatures of a canine pissoir

Sally (la Sal, the Salster) is part whippet, part Labrador and part dormouse. She is 16 years old, stone deaf, three-quarters blind and has dementia. She sleeps like the dead all day but loves her evening walk. We’ve decided that for as long as she enjoys her walks and remains continent indoors we’ll delay taking her to the vet and asking him to put her light out.