Our Bea is getting up there in years. She used to be a big couch sleeper but has lost her sight and can no longer make the jump. We have casper mattresses and love them so I figured "why not?". Bea is a rescue and geriatric. She's a sweet girl who had an unfortunate life and deserves a little luxury. 

She is near 30lbs give or take a pound so I opted for the medium just in case. I probably could have easily gotten a small. She is a Boston Terrier which are rather stocky in nature despite some of them getting to be 30 - 35lbs . That's okay, more room for her to sprawl. 

Well she's been absolutely smitten with her bed and is snoring loudly as I type this.