Walk the boundary before the lead comes off
A holiday home garden is unfamiliar territory for both of you, so treat the first inspection as a job, not a glance from the patio. Clip the lead on and walk the full perimeter slowly, looking at the fence from your dog's height rather than yours. A gap that seems minor while you are standing can be an obvious exit route to a dog with his nose at ground level, especially in a place full of new smells pulling him outward.
Height, gaps and the gate test
Measure the fence honestly against what your dog can actually do, not what he usually bothers to do at home. A dog who has never challenged your own fence may try harder here, where cats, other dogs and unfamiliar sounds sit on the other side. Check for spaces between panels, missing boards, chain-link he can push through, and gaps beneath gates wide enough for a head and shoulders. Then push-test every gate and panel with firm pressure. Latches that lift easily, hinges that sag and panels that flex all fail the test, even if the fence photographs well in a listing.
Ground level is where escapes start
Run your eyes along the soil line for the whole circuit. Look for soft earth a dog could scrape out quickly, existing holes from previous guests' pets or wildlife, gravel that shifts, and decking or paving edges that hide a dip underneath. Check corners carefully, because two fences meeting often leave a triangular gap neither panel fully covers. Also look underneath sheds, raised decking and stored garden items, where a determined dog can squeeze into a hidden run that ends beyond the fence. If you find a suspect spot you cannot fix, block it with heavy garden furniture or a solid object before any off-lead time, and recheck it after rain softens the ground.
What sits on the other side matters
Peer over or through the fence where you safely can. A low fence beside a busy road, livestock, a neighbour's territorial dog or an unfenced drop is a very different risk from the same fence backing onto a quiet lane. Also scan your own side for launch pads: log piles, benches, bins and low shed roofs stacked near the boundary can turn a fence he could never clear from flat ground into an easy climb. Move what you can, and treat what you cannot move as lowering the fence's real height.
First garden sessions stay supervised
Even a garden that passes your inspection earns trust gradually. Stay outside with him for the first several sessions, watch which stretches of fence hold his attention, and recall him away from any spot he studies too closely. Keep early sessions short and calm rather than letting excitement build around squirrels or passing dogs. Note which gate visitors will actually use during the stay, and check its latch twice, because the gate you inspected may not be the one left unlatched after a delivery. If a weakness appears mid-stay, he goes back on a long line in the garden until you can block it properly. Should he still manage to get out in an unfamiliar area, KinsLe's Lost Pet Alert System can send word to nearby members around the holiday address while you work the surrounding streets.