Dogs are not born trail-fit
A dog that runs a park loop with joy can still finish a six-mile rocky trail limping. Endurance, paw pad toughness and heat tolerance are all trained, and they build at roughly the same pace as a human's — a few weeks, not a weekend. Start at half the distance you think your dog can handle, on soft ground, and add about ten percent per outing. Puppies under twelve to eighteen months should stay well short of long or steep hikes because their growth plates are still open; ask your vet about your specific breed's timeline.
Heat is the risk that catches people out
Dogs cool almost entirely by panting, and a dog carrying a coat on a sunny slope reaches trouble long before its owner feels warm. If the combined temperature and humidity feel heavy to you, halve the plan. Watch for the early signs — frantic panting, thick drooling, a bright red tongue, slowing down or seeking shade repeatedly — and stop immediately if you see them, wetting the belly, armpits and paws with cool (not ice) water. A cooling vest soaked at a stream buys real degrees on exposed trails, and a light-coloured coat reflects more sun than a dark one. On genuinely hot days, hike at dawn or skip it.
Check the ground before you check the view
Asphalt, slickrock and sun-baked sand can exceed 140°F while the air reads a pleasant 85°F. Press the back of your hand to the surface for seven seconds; if you cannot hold it, your dog should not walk on it. Sharp scree, ice and de-icing salt each damage pads differently. Dog boots solve most of it, but they need breaking in — a few short sessions at home first, or your dog will high-step comically and then refuse. Paw wax is a lighter-weight alternative for moderate conditions. After every hike, run a hand between the toes for grit, thorns, cracked pads and ticks.
Water, and a pack that carries some of it
Plan for roughly an ounce of water per pound of dog per day, and considerably more on hot or strenuous days. Do not rely on streams: stagnant water carries giardia and blue-green algae, which is genuinely dangerous. A squeeze bottle with an attached trough lets you offer water one-handed on a narrow trail, and a collapsible bowl works at longer breaks. A fit adult dog can carry up to about ten to fifteen percent of its body weight in a properly fitted dog pack — start empty, then add weight over several hikes, and keep the load balanced side to side and sitting over the shoulders rather than the lower back.
Leashes, wildlife and other people
A hands-free waist leash with a bungee section keeps your hands available for scrambling and absorbs the shock when your dog spots a squirrel. Most trails require leashes; the ones that do not still contain wildlife that your dog can injure or be injured by. Step off the trail and let horses and uphill hikers pass. Carry waste bags out — a bagged pile left beside a trailhead is worse than no bag at all.
The small kit that goes in every pack
Tick remover, tweezers, vet wrap, a spare leash, a length of gauze, an emergency booty for a torn pad, and any medication your dog takes. Add a small LED light on the collar for anything that might run past dusk. Know the nearest emergency vet before you park. None of it weighs much, and the day you need one of these items you will need it badly.