Slightly, if the other arguments put forward on this thread are not working, please ask him what part of HIS disposable income he will be giving up to pay for the dog's upkeep? Has he actually sat down and done the maths? Has he factored in the insurance, vets' bills, vaccination, worming, kennel cost when you go on holiday, collars and leads, possibly coats, possibly a special diet that is more expensive than feeding a small child, cost of extra cleaning, possible change of car (we now have an estate car
after having a Ford Fiesta !!, possible extra cost of professional dog walker to act as backup if you or he are ill or unavailable, poo bags, professional grooming for many breeds, dog beds and toys and not forgetting if you do get a pup, the cost of replacing all the chewed shoes/toys/furniture. Even with an adult dog it is impossible to maintain the housekeeping standards of pre-dog days.
Will he be giving up his boy's beer night, or his other hobbies for this? Because if he isn't the money will be coming out of the FAMILY pot, and this is not fair on you or DC. The cost of a dog could easily add up to the equivalent of a nice family weekend away each year, or an awful lot of family treats each month. If you're well enough off for this not to be a problem, then great, but if you are on a more average income this really is something to look at very seriously.
Please remind him that even with pet insurance, vets bills will need to have an excess paid, and generally insurance won't cover things like worming and vaccinations and routine dentals, which believe me are NOT cheap. Covering the cost of the dog going into kennels is equivalent to the cost of another person going on your holiday with you, quite often, and all the best kennels get booked up months in advance, especially at times like August and Christmas.
Ask him to think ahead to when the dog is old. Will he be the one to take the dog for physiotherapy or hydrotherapy sessions? Or to ensure a special dog bed, ramp for the car? To make sure dog has its daily medication and to ensure pain levels are carefully monitored? To spend time fussing over a special diet when it is ill or can no longer tolerate certain foods? To be aware that bladder control can be weaker in older dogs so you can't leave them for so long, and quite often they'll wake you in the middle of the night? And by that time your DC will prob have left home and be having a ball at Uni, and you will be thinking "Why am I having broken nights when my kids have left home?" Will he be the one doing this? HONESTLY? Because if he is not even willing to walk a dog from the local dogs home occasionally at the moment to demonstrate his commitment, then I think I can guess teh answer. I may sound harsh but a dog is a long term commitment, and it is not fair on you or the dog to do this without 100% commitment.