An old conceptual illustration done back in September of 2017 of different demohound colourations. From top to bottom they're based on a nautilus, a baby tapir, a vampire squid, a pyjama squid, common fruit-piercing moth caterpillar, and snowy owl.
Although I didn't end up going with any of these, demohounds have the ability to change their skin colour, so they would come in a variety of colours of patterns regardless, even including white, in snowy conditions. The nautilus colouration was actually the "original" colour scheme designed for the species in an even earlier drawing.