I agree with the others, I'm afraid.

When Milo was 14 months old, we fostered a 10 month old male called Mikey so they were exactly the same age as yours and your possible newbie. We were only fostering Mikey as his previous family wanted him gone at really short notice, but we hoped that we'd be able to keep him. As it happens, it really didn't work out.

Milo was miserable, he became withdrawn and all training that we'd done with him went completely out the window. Admittedly, Milo's not the most assertive of dogs and Mikey was quite bossy, but I don't think that was entirely the problem.

In hindsight, I don't think Milo would ever had been happy sharing us with another male dog, and he was too young at the time. We then had to make the heartbreaking decision to find a forever home for Mikey, and we still miss him and think of him now.

We recently took on a year old Cocker bitch (Milo was just over 2), and it's been a completely different story.

Milo and Mocha are the best of friends, and his reaction to her joining our family is completely different to when we tried to introduce Mikey. I'd wait until your dog is a bit older before introducing a second one, but depending on your dog, I wouldn't say that this definitely couldn't be another male.
