Answer: What you describe isn't all that unusual, but that still doesn't make it acceptable! Dogs generally won't frequent a place that's difficult to manuever so a ground cover with trailing stems (vinca minor, for instance) might keep them out. Failing that,
Pyracantha coccinea 'Prostrata' (Prostrate Fire Thorn); and Berberis thunberia "Atropupurea Nana" both have thorns, which should keep the dogs out.
Sometimes uneven surfaces deter animals; small shrubs planted in a group (heather, lavender, etc.) might help - although they may consider the plants a fire-hydrant alternative.
There may very well be materials you can spray that would be offensive to dogs, so you might want to check with the pet store.
A final thought is a sprinkler set up with a motion detector. If you can catch the dogs in the act, a stream of water at the precise moment may scare them away.
Wish I had more suggestions!
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