So, you want to get a dog! Cool! There are so many things to think about, of course, and the resident cat is happy to be your one and only, as cats always are, so a new member of the family is certainly going to affect him. What we don't know yet, is how. Has he ever seen a dog? Has he ever had a buddy of any kind? Another cat even? If not, he could be very upset....or, on the
other hand, if he happens to find the puppy interesting, they could become pals right away. It's rare, but it happens. However, cats are prone to becoming depressed if their lives are turned upside down.
Now, the other thing to think about is your own experience with dogs. Are you prepared for the intensity of life with a new pup? And I do mean intense.
You'll probably want to be prepared for potential problems. If they do not get along...and that will be up to the cat, as it usually is...do you have a way to keep them apart?
The overriding concern will be for the cat's well being, mostly emotional, though he could be physically at risk if the dog happens to have a high prey drive. (Never ever leave them alone together unsupervised.)
It can be complicated, but it could also go well. You won't know until you try. But, you might consider making it possible to change plans somehow...like, not buying from a breeder (yet), where your action is more likely to be permanent and you can't go back. And you wouldn't want to.
Can you try fostering a dog first? This would give you an idea of how it could go, and what the cat's reaction will be. Most shelters are extremely grateful for temporary foster homes, and that would relieve you of taking a permanent action you couldn't easily reverse.
Also, if you foster several during the course of a few months, or even a year, it would give the cat a chance to get used to a dog, and allow him time to accept that it will be OK when you go for the
Or, if he declines in health or emotional status, you'd know if a dog was a good idea or not to bring into his life.
If you do decide to foster a dog first, I would recommend fostering an older dog. First, because no one wants them anyway, and shelters end up euthanizing millions of them every year. So it would give an old guy a little extra time for love in this world. Second, because an older dog who has been around cats would help ease the transition for the cat! He could teach him that dogs can be good pals.
And, third, the shelter would be more than grateful (if they care...some don't), to have an unwanted dog find a home, even if for a little while. Just be sure to let them know this isn't permanent, so they won't be surprised if you need to bring him back later.
Give yourself some time to think about this and do some research...perhaps just do some dog walking at a shelter if you haven't been around dogs very much. Or visit friends or family if they have a dog and ask questions. Have a friend bring a dog to your place for a visit to see what the cat thinks!
In any case, don't expect immediate results. Everyone needs time to settle in and get used to each other.