Thunder overhead on open ground leaves you two problems at once: lightning exposure for both of you, and a dog whose panic rises with every crack. The order of work is simple. Reduce exposure first, keep physical hold of the dog throughout, and let calming wait until you are somewhere with walls or a roof. Checking the forecast before exposed routes, and turning back at the first distant rumble, prevents this situation far better than any handling once you are caught in it.
Get Off Exposed Ground and Away From Lone Trees
The walker leaves ridges, summits and open plateaus promptly, dropping to lower ground by a direct safe line rather than finishing a planned loop. An isolated tree is not shelter; a lone tree in a field, a single tree on a ridge and the edge of open water are all places to move away from, along with metal fences, gates and machinery that a walker might otherwise lean on. The walker also avoids standing in streams, flooded dips or boggy hollows while descending, and keeps away from a flock or herd sheltering in the same low ground. If a building, a barn, a staffed facility or a car is reachable, the walker heads straight there and waits the storm out inside, with the dog settled on the floor away from doors. Distance judgement helps on the way down: thunder that arrives after a long gap is still some way off, while a crack that follows its flash almost at once means the storm is close and the descent should start immediately by a direct safe line. Forecasts are checked before exposed routes rather than on them, and the walk is shortened or moved to low, sheltered ground on any day when storms are due during the walking hours.
Hold the Dog Close and Handle Steadily
The walker shortens the lead and brings the dog in close, checking that the collar or harness is snug, since a frightened dog lunges at a crack of thunder and can back out of gear that felt secure in the garden. One hand holds the lead short and the other stays free for gates and balance, and the walker speaks in a low, even voice without fussing or scolding. Movement stays calm and steady; running raises the dog's alarm and raises your own exposure time on the descent. A dog that freezes or refuses to move is waited with for a few breaths, then encouraged forward with a treat or a toy rather than dragged, since dragging a panicking dog risks a slipped collar at the worst moment.
If No Shelter Is Reachable, Then Head Home Afterwards
The walker caught in truly open country with no shelter in reach crouches low on the balls of the feet, close to the ground, while keeping hold of the lead, and stays out of ditches filled with water and away from any lone high point nearby. That crouch is a last resort for the minutes when the storm is directly overhead, not a place to settle, and the walker moves on towards shelter once the thunder eases and the gap between flashes and sound grows. Once home, the dog is dried, offered water and left to settle in a familiar interior room, and the walker notes how the dog coped for the next forecast check. If the worst happens and a panicked dog tears free, use the Lost Pet Alert System in KinsLe to alert nearby owners along your route, and let whoever manages to catch the dog contact you through the alert.