In my experience very slick and warm, the texture is very different than a humans skin, almost like the slickness of silicone in a way (never leave a dogs penis exposed to air without keeping it lubricated, there is a reason dogs squirt so much, its to ensure the membrane covering it doesnt dry out during a 30+ min tie, keep in mind their penises are extra sensitive compared to a humans you want them consistently lubricated, do not allow them to dry out as this leads to discomfort and possible infection [UTI's], if the texture feels even slightly rough you need to use more water based lube or cup your hand to catch cum and use that as lube to ensure they are safe and enjoy the overall experience)