I think the most important thing I can tell you is that when you have a senior pet and bring home a new puppy it is that you give them the gift of time to acclimate. The first thing to keep in mind is that this is a huge change for your senior dog. They are going from a life of leisure and having you all to themselves to having a puppy shadowing their every move. It’s typical to expect at the beginning of the introduction for your senior pet to be standoffish and maybe even a bit grumpy. This is completely normal. I will say that it is very rare to see a senior dog become aggressive toward a puppy. They may get protective or even a little snappy, but this often goes away with time.
With all that being said, it is important to give your senior dog some latitude. If the puppy is being obnoxious (and they will be) by pestering your senior, it might be best to give all parties a break. I also think it’s important to spend some quality time with your senior as well (walks, playing, and more…this is all good one-on-one attention) because you won’t get that time back. Also, try to make sure the puppy observes the behaviors that you want it to learn from your older dog…your senior can be a great teacher!
It may seem impossible at first that the two will ever get along but give it time and patience and after a few weeks they will most likely be best friends!