Older dogs can be stubborn, they have a set routine in their territory. A new puppy can have seemingly boundless energy, this may disrupt your older dogs' normal routines. Gauge your older dog’s temperament, if your senior dog is territorial, they may have a harder time sharing. If they’re a big dog who throws their weight around, that could prove harmful to your puppy. If the older dog is a small breed, the puppy might harm them while they learn to play. Research your breeds to determine if blending them together is a good fit. Before introducing your dogs, have both of them examined by your vet, make sure that they’re both up-to-date with any necessary vaccines.
Find a neutral territory, before bringing your puppy home, take them and your senior dog to a neutral location, somewhere outside like a garden or on a walk is best. Use a leash, keep both dogs on a leash with someone calm at the other end, keeping the leash relaxed and loose will help relieve their anxiety. Follow your dog’s lead, some dogs may warm up to one another faster than others, that’s okay, being patient and waiting for your dogs to make the first moves will promote a safer, more relaxed space for them to become acclimated.
Watch body language, your dog will show how they’re feeling with their whole body, keep an eye out for posturing, fur standing on end, growling, or aggressive staring, if you notice this type of behavior, calmly direct their attention elsewhere. Take them home, let the dogs interact in your yard, since it’s no longer a neutral environment, moving slowly is important, following the previous guidelines, make sure that they are still comfortable with each other. Keep them apart, when you can’t be around to closely monitor their interactions, keep your dogs separated, keeping your puppy in a crate will help prevent accidents with your senior dog.