Only read the OP.
PLEASE do not get a dog if your DH doesn't agree. My DP did this to me, he bought a dog on the spur of the moment. The dog was totally unsuitable. I was horrified but thought, OK, its here now and i hate people who give up on animals. Anyway, i lasted a day, i was miserable and withdrawn, the dog was a wrong'un and i made him take it back - We lost the £350 that my lovely fuckwit DP paid for the animal. Don't get me wrong, i love dogs, we have a dog - but it was a joint decision, we both went and chose him, spent time getting the right dog. No nasty surprises.
Getting a dog is a massive deal, they become part of your family - to lie about it to your DH, its a bit underhanded at the very least. Shows a distinct lack of respect and consideration for the other partner. I told this to my DP even though the dog he bought was supposedly for me and my favourite breed that he knows i love, the actual dog itself was wrong for us.
Yeah, it could end well your DH will grow to like the dog, but there will always be an underlying resentment of the animal, no matter what.
If you really want a dog, make it absolutely clear to your DH how important this is to you and that you really want to get one. That you would like his blessing and want him to love the dog too. Hopefully he will respect you enough to say go ahead, respect is a two way street.