[Lee B]

One thing to consider when purchasing stairs is the width of the tread and the height of the riser. The stairs I got for the Yorks have tread/riser measures of 5"; these were built especially for toy breeds.

Longer dogs, like Doxies, need a wider tread (because they're longer and need more room), even if they don't need the higher riser. That would also work for larger, frailer animals like the heavy beagle described above.

Bigger dogs have stairs appropriately sized for tread/riser.

So look for the proper size for your dogs. One benefit: the smaller the tread depth, the less the overall "footprint" of the stairs, the less room it takes up in, well, your room. And they're usually less expensive than the larger ones.