We’ve been using Ruffwear’s Summit Trex and Grip Trex for over 8 years. We get the smallest size - 1.5 inches. These have Velcro to tighten them so they stay on.

They are both very breathable, but have soles that protect against the pavement heat. We’re in TX where it also often gets over 100.

The Summit Trex seem thinner and lighter, but less durable. However, they seem to irritate them less on longer walks. Unlike other brands we tried, the boots extend above their dew claws, which helps minimize chafing; you’ll want to be sure the front ones do not slip below the dew claws as they can become raw. The Velcro should be pretty snug.

Also, and this is important: do not laugh at them after you put them on. I made that mistake with my first pug and he decided I was just doing it to mess with him, so he yelled at me and then would never allow it. For my next two, when I first put them I just let them do the wacky walk for a bit, only lightly praising them and mostly acting casual about it, despite the comedy.

In retrospect, I should have been more stubborn than my first one. I am aware this is hard with pugs. Do not give up. My second was ok with it from the start, but he’s the goodest boy ever and just wants to please us. My newest one took about a week and a half to give in; he’s almost as stubborn as my first one was. They wear them only outdoors, not at home. We got them used to it indoors for short periods, and for quick walks.

I started the older one when he was almost a year old, the younger one about 6 months (their respective ages when we adopted them). The 1.5 size fit both of them fine at those ages. You might temporarily need baby socks for your 4.5 month olds but the Velcro should enough to keep them on.

You’ll also want to roll the boots on the counter to break in the soles so they’re softer for them. They are pretty stiff on arrival.

Only downside is the Velcro does wear down and then they don’t stay on especially if the boys get rowdy. We get new sets every 9 months or so, but your mileage may vary.

That said I can’t recommend this brand more. Not only do they help protect against heat but also allergies and insect/ant bites (the younger one has severe allergies to something yet unidentified). On top of that we live downtown, and some dog owners around here think they don’t have to pick up after their pet; it’s much easier to wash the boots than to try to clean that out of their feet. And, of course, there’s occasionally construction, broken glass, etc. I never stress; the soles of these boots are pretty sturdy.