The ball is by the back door and your dog is looking at it. Then at you. Then at it again. You have thrown it 40 times today and they would like a 41st.
This is different from a dog who will not bring the ball back. That is about holding on to a thing. This is about the game itself becoming the only channel your dog has.
Why fetch takes over
Fetch is fast, repetitive and highly predictable, and it rehearses the chase part of a hunting sequence over and over without ever finishing it. For some adolescent dogs that combination is close to irresistible.
Fast repetitive exercise like this tends to raise arousal rather than lower it. Your dog gets fitter and keener, and the asking gets louder. That is why throwing more of it feels like it should work and does not.
What over-aroused looks like
Your dog cannot take food during fetch, or takes it hard and without noticing.
They bark, spin or nip at your hands between throws.
They cannot settle for an hour afterwards, and pace instead.
Nothing else on the walk registers. No sniffing, no other dogs, no interest in you.
Put fetch on a shape
You are not banning the game. You are making it one part of the day instead of the whole currency of it.
Put the ball away, out of sight, between sessions. A visible ball is a request your dog makes all day.
Decide the number of throws before you start. Six or eight, then the ball goes away while your dog still wants more.
Start and end the game with your word, not with your dog's staring. The game begins when you say so.
Ask for something small between throws, like a sit or a hand touch, and pay it. Two seconds of thinking inside a fast game does a lot.
Follow every fetch session with a chew or a scatter feed on a mat, so coming down is part of the routine.
Build the other channels
A sniffing walk at your dog's pace, with no ball in your pocket. Following a nose does calming work that following a ball does not.
Food puzzles and scatter feeding, so at least one meal a day is a job.
Search games. Hide food or the ball itself and let your dog find it, which uses the nose rather than the sprint.
Tug with rules, taken out and put away by you, for dogs who enjoy it.
Short settle practice on a mat, paid for staying calm rather than for moving.
Relaxation is trained as a behaviour in its own right, in short repeatable sets below threshold. A fetch-fixated dog usually has very little practice at it.
Safety note
Speak to your veterinarian if your dog cannot rest at all, is losing weight or condition, or if the fixation arrived suddenly. Sudden behaviour change warrants a veterinary examination. Pain often shows up as a change in behaviour rather than as obvious lameness. Hard sprinting, skidding turns and jumping for a thrown ball also load a growing dog. Ask your veterinarian what is reasonable for their age and build.
What to expect
The first few days after the ball goes out of sight are usually noisier, because the asking has always worked before. Owners generally describe a dog who settles more easily within a couple of weeks, with the asking still there but answerable.
Today's version, in one line: ball out of sight from now on, 6 throws tonight when you say so, then a chew on the mat.