Nobody notices their dog getting old. You notice it all at once, months late, usually because of something small — they did not come upstairs, or they took the sofa in two attempts instead of one.
Large breeds are seniors from around six, small breeds from about ten, and most dogs somewhere around eight. Here is what actually changes, and what helps.
1. The floor becomes a problem
This is the one owners miss for longest. Hardwood, tile and laminate are frictionless to a dog with weakening hindquarters. Every slip is a small panic and a small strain, and dogs respond by moving less — which accelerates the muscle loss that caused the slipping.

Runners and rugs along the routes they actually walk — bed to door, sofa to bowl — will do more for an arthritic dog than most supplements. A waterproof grip pad under the bed and bowl area covers the two spots where they stand longest.
2. Jumping stops being free
Onto the sofa, into the car, off the bed. Each of those is a joint impact, and in an ageing dog the landing is what does the damage. They will keep doing it — dogs are stoic to a fault — right up until they cannot.

Get ahead of it. A set of three-step folding stairs for the sofa or bed, and a car ramp for the boot, remove the two biggest repeated impacts in a dog's week — both live in dog ramps and stairs. For a taller bed or a high vehicle, the four-step version gives a shallower, kinder angle. Introduce them before they are needed, with treats — a dog in pain will not learn a new skill.
3. Getting up takes a moment
The first thirty seconds after lying down are the tell. Stiffness that eases with movement is classic osteoarthritis, and it affects around four in five dogs over eight.

An orthopaedic bed with genuine support — thick enough that the dog does not bottom out onto the floor — is the daily-use item that matters most. A firm supportive lounger with a raised edge lets them prop their head and get leverage to stand, which a flat cushion does not — compare the orthopedic dog beds. And it needs to be somewhere warm; cold stiffens an arthritic joint noticeably.
4. Stairs become a calculation
Watch them pause at the top. That pause is the dog doing arithmetic about whether the descent is survivable.

For a big dog who is still mobile but unsteady, a support sling is the single most transformative object in senior dog care. You take some of the weight over their hips, they keep walking, and the walk stays possible for another year. It is also what gets a large dog out to the yard at 2am without you injuring your back.
5. Eating gets uncomfortable
An arthritic neck and shoulders make the head-down crouch of eating genuinely painful. Dogs respond by eating less, or by eating fast and standing up — neither of which you want.

A raised bowl removes the crouch. (One caveat, covered in the fast-eater guide: raised bowls are for comfort, and there is some evidence they may raise bloat risk in large deep-chested breeds — check with your vet if that is your dog.)
6. Sleep gets worse, and so do nights
Older dogs sleep more in total but worse in stretches, and canine cognitive dysfunction — dog dementia — shows up first as night pacing, staring, and confusion in familiar rooms. It is common and it is treatable enough to be worth raising with a vet rather than accepting.

Practical help: keep the layout of the house constant, leave a nightlight on, and give them a bed with sides they can feel — a bolstered neck-support pillow gives a disoriented dog a physical boundary to find in the dark.
7. They get cold
Less muscle, thinner coat, worse circulation. An old dog who used to sprawl on tile now seeks out the radiator, and cold makes arthritis measurably worse. Move the bed away from draughts and doors, and put something warm in it. This is not indulgence; it is analgesia.
8. They stop asking
The cruellest one. Dogs in chronic pain do not limp dramatically — they simply do less. They stop meeting you at the door, stop offering the toy, stop the pointless joyful lap of the yard. It reads as "slowing down with age," and it is very often untreated pain.
If your dog has quietly stopped doing something they used to enjoy, that is a clinical sign. Take it to a vet. Modern canine pain management is genuinely good, and the number of owners who describe their dog as "years younger" a couple of weeks into treatment is not a coincidence.
9. The walks change shape
Shorter and more frequent beats one long march. And keep them going — the instinct to rest an old dog completely is wrong; muscle is what holds a bad joint together, and a dog who stops walking loses it fast.
Sniffing counts. A twenty-minute walk where they read every lamppost is more tiring, and more satisfying, than a brisk mile. Let them stop. There is nowhere to be.
The thing worth saying
Most of what makes an old dog's life better is not medical and not expensive. It is grip on the floor, a ramp instead of a jump, a warm bed with sides, and paying attention to the small things they have quietly stopped doing.
More reading: the honest bed buying guide · how to dry a dog without a fight