“I bought this to help keep mosquitoes from bothering my dog while we hike. It fits about as expected - she's long and lean, so I got her a large based on the size chart. It covers probably 2/3 of her back and has a little belly room, but I think a M would be too small (and XL too big). Mosquitoes still land and bite on her hindquarters, but not as bad as without the shirt. The material does seem to cool a bit, especially if I keep applying more water as we hike.
The one downside I have noticed is that it seems to bunch under her harness. Would love it if the next iteration had a collar/harness attachment point.”