Good suggestions wanted, dog won't release

[martinnitram]

Open to suggestions to encourage our terrier to release on command.
He will happily fetch and return his toys but he's not willing to let them go.
Hard toys can be taken but anything soft that can be bitten down on he will hang on to till death, the same applies to your coat given the chance.
He's a 4 and a bit month old typical terrier, bright and keen to learn with a rebellious side,

Let's hear what worked for you .

[martinnitram]

Aggree with it being a breed trait, swapping for another toy works but looking to get him to release on command.
The live rat suggestion is interesting, £ 2.00 each in the pet shop and they have plenty of stock