What should your dog watch?

Yes, but not what you see. Dogs are dichromatic: they have two kinds of colour receptor where you have three, which leaves them a world built out of blues and yellows. Red and green arrive as murky variations of the same thing. They also refresh faster than we do, which is why dogs largely ignored old television sets — to a dog, a 50Hz screen flickered like a strobe. Modern screens are quick enough to look continuous.

This is why everything we draw is drawn inside the blue and yellow range. It is not a stylistic choice. A cartoon full of reds and greens is, to the animal watching it, mostly grey.

At a low volume, no. The thing worth avoiding is not the duration but the surprises: a video that ends hands your dog over to whatever the platform plays next, and that is usually louder, brighter and not ours. If you are out for a full day, use something that does not finish.

And watch your dog rather than the clock. A dog who settles and sleeps is getting something from it. A dog who is pacing, panting or barking at the screen is not, and leaving it on for longer will not change that.

Almost certainly, and this is the single most common worry we get. Most dogs are listeners, not watchers. The sound does the majority of the work — a steady, predictable, low-tempo sound tells a dog that nothing in the room requires his attention, and that is the whole mechanism.

If your dog lies down, sighs, and goes to sleep without once looking at the television, it worked perfectly.

No, and anyone telling you otherwise is selling something. True separation anxiety is a panic disorder: the dog is not bored or lonely, he is frightened, and it responds to gradual desensitisation work with a behaviourist, sometimes alongside medication from a vet.

What video can do is take the edge off ordinary, mild loneliness, and make the room less silent during the first hour. That is a real and useful thing. It is not a treatment.

Normally, just above the background noise of the room — quiet enough that you would happily have it on yourself. A dog's hearing is considerably better than yours, so what sounds gentle to you is already quite present to him.

Fireworks and thunder are the exception. On those nights the job is to cover the bangs, so go louder than feels polite, and start before the noise does.

For puppies, keep it short. A puppy tires fast and the goal is a nap, not attention — twenty minutes that end in sleep beat three hours that end in a wired puppy. It is also genuinely useful for the first nights in a new home, when the silence is the problem.

For older dogs, two things change. Hearing often goes first, so the picture matters more than it used to — and our animation is drawn to stay readable with the sound almost off. Sight can go too, in which case ignore the screen entirely and treat it as sound.

Cats are dichromatic too, in roughly the same blue-and-yellow way, so the colours work. What differs is the appetite: cats want small, fast, erratic movement — birds, insects, something darting — where dogs settle better with slow, predictable motion. Several of our videos have cats watching them. They tend to pick the ones with seals.

All of it is free, and no. Every video is on YouTube, this test asks you for nothing, and there is no account to make. We make money from the channel itself, which is a straightforward enough arrangement: if the videos are useful, people watch them.