The hard-hitting campaign - Save your dog's life for just £25 - is by agency 141 and explains that neutered dogs are less likely to wander away to find mates, which causes road accidents or unwanted births.
The campaign specifically targets four regions - the Northeast, Northwest, Wales and Northern Ireland - where 70 per cent of the 10,000 dogs destroyed by local authorities in 2003 lived.
Recipients are encouraged to phone a hotline to find their nearest vet who can do the operation. Dogs Trust has recruited 600 vets that will carry out the neutering for £25 with the rest of the cost billed to the charity.
Kelly Glover, head of campaigns, said: "It's far more expensive to re-home stray dogs than to pay to get dogs neutered, so the campaign is being backed by a £1.5m fund to subsidise the operation for the dog's targeted D/E householders."
The campaign is the last in a series of four creatives which began last year, each with a different theme, but all explain that neutered dogs live longer.