Angelfishy

Because play is not optional for a dog. It's how they use their nose, their jaw and their problem-solving — the instincts they were built around, in a life that no longer asks much of them. A toy gives those instincts somewhere to go.

Dogs who play are calmer, sleep better and are less likely to find their own entertainment in your shoes.

Fewer out than you think, and more in the cupboard than you think.

Three or four available at a time is plenty. A basket of twenty toys isn't twenty times the fun — it's twenty familiar objects, none of them interesting. Keep most of the collection put away and bring them back in rotation.

Watch what they already do.

A dog who shakes things wants something with weight and a long body. A carrier wants something soft and light enough to hold for an hour. A squeak-obsessive wants sound. A dog who noses everything wants texture and crinkle.

Present one toy at a time rather than a pile — the reaction is much easier to read.

Because they're valuable, and guarding valuable things is normal dog behaviour rather than a character flaw.

It becomes a problem when it escalates — stiffening, freezing, growling over a toy that someone approaches. Don't take the toy away to prove a point; that teaches your dog that hands arriving means good things leaving. Trade for something better instead, and if it's escalating, get a behaviourist involved early.