A horse walks across the screen and your dog is off the sofa, barking at the television. They ignored it for the first 9 months of their life.
Nothing has gone wrong. Your dog has got better at noticing things, and a screen is one of the things they can now see.
Why it starts in adolescence
Vision, attention and reactivity to novelty all shift through adolescence, roughly 6 to 24 months. Things that were background last month are worth a response this month.
Responsiveness to your cues also drops around the onset of adolescence and comes back later in the stage. So your dog notices more and listens less at the same time, which is why the evening feels loud.
From your dog's side, barking works. The dog on the screen barks back, then leaves the screen. Nothing about that teaches them to stop.
Tonight: change the room, not your dog
Working below the threshold at which a dog reacts is the condition for learning near a trigger. In a living room you get below it by changing what your dog can see and hear.
Move your dog's bed so the screen is behind them or side-on. A dog lying square in front of a TV is watching it all evening.
Drop the volume. Most screen barking starts with a sound, not a picture, and 2 notches quieter is often enough.
Turn a lamp on. A bright room makes a lit screen much less like the only moving thing in the dark.
Pick something else for the nature documentary. Wildlife programs are the hardest possible viewing for a dog who has started this.
Have something to chew or lick going on the mat before the TV goes on, rather than after the first bark.
Then pay the quiet look
Do this in short sets, with something mild on screen, when the house is calm. Three minutes is a whole session.
Sit with 15 pieces of food. When your dog looks at the screen and does not bark, say "yes" and feed at your knee, away from the TV.
If they bark, say nothing. Pause the program or mute it, wait for quiet, and carry on. Silence is more useful than any word here.
If they cannot stop once started, take them out of the room calmly for 60 seconds, then let them back in. Nothing said, nothing scolded.
Stop after 3 minutes or 10 pieces. Then turn it off and let the evening be ordinary.
Reward-based training is associated with higher reported responsiveness and fewer reported problem behaviours, and it is what the veterinary behaviour guidance recommends. That applies to a living room as much as anywhere.
What not to do
Do not laugh, film it, or call the family in to watch. An audience is payment, and a funny habit becomes a nightly routine within a fortnight.
Do not play dog videos, doorbell clips or animal channels to set your dog off on purpose. Every rehearsal makes the next one faster.
Do not shout over the barking. From your dog's side you have joined in, loudly.
Do not use a spray bottle, a rattle can, a corrective collar or an ultrasonic device. A review of aversive methods found them associated with worse welfare outcomes and no training advantage.
Do not let your dog bark at the screen unattended in the evening. Unsupervised practice is still practice.
When it stops being a TV problem
For most adolescent dogs this stays a nuisance about screens. For a few, it is the first visible part of something wider, and that is worth naming.
The barking has spread from screens to windows, phones, mirrors, or reflections in the oven door.
Your dog cannot come away from the screen at all, or goes back to it once the TV is off.
A growl underneath the bark, hackles up, teeth on the screen, or redirecting onto a person or another dog.
The behaviour looks driven rather than reactive: staring, scanning, or waiting in front of a blank screen.
Safety note
Book a veterinary appointment if any of those describe your dog. Sudden behaviour change warrants a veterinary examination, and pain frequently presents as a change in behaviour rather than as obvious lameness. Take a 30 second video with you. Ask for a referral to a veterinary behaviourist, or a qualified behaviour professional who uses reward-based methods. Ask at the first appointment rather than the third. We will not name a disorder here, because that is a diagnosis and it belongs to someone who can watch your dog in person.
Behaviour change is built from management plus reinforcement together. The management is where the bed sits and how loud the TV is, and the reinforcement is food paid for the quiet look.
What to expect
Most owners describe a quieter evening within 2 to 4 weeks once the seating and the volume change. Expect the odd outburst at an unlucky program. Nobody can promise you a dog who ignores screens for life.
If the barking is really about everything rather than the television, the Assessment will name the pattern underneath. It is free, takes about 3 minutes, and asks for no email address.
Today's version, in one line: volume down 2 notches, bed side-on to the screen, chew down before you press play.