Bichon Pug

can we predict if a dog will likely be friends with another or not?

he's a pug, she's a bichon. they're both neutered. He weighs twice as her but are approximately the same size. He's calm and barely playful, she's hyper and can't stop moving and playimg. He's 4 years old and she's just 1.
Please let me know what you think as I wish to dog sit for my friend who's travelling and I wish to know if I'm making a mistake

You could have him over for a test overnight - that way, you'd know before your friend left for parts unknown...

Chances are, they'll be fine - I know another 'couple' that consists of exactly the same combination and they are like a very proud guy with his trophy wife

If you were truly nervous, you could put up a metal baby gate, and keep them apart for a while, but that will probably be good for about 10 minutes. You should be able to determine whether or not there's a problme right away- but really, I doubt you'll have one.

My only concern would be the male marking in the house - and again, a baby gate would keep this young man in the kitchen, and you should also be able to crate either one.

Any new combination should be cause for consideration, but on this small a scale, it isn't much of a risk. My money is on them being wonderful playmates, and you'll have a harder time sending him home.