Yes the dogs penis is sensitive but it's like the head of your cock (circumsized) . Sensitive and uncomfortable with a dry hand but when surround by a warm fleshy hole lubricated with lots of fluids, it is really pleasurable. Idk why people say we can't get feedback from dogs. If anything, it is even MORE clear than a human cus you know they won't fake it or lie. A dog will squirm or get away, most importantly, will stop cumming and begin to shrink if it's uncomfortable for them.
Also, no need to suck. I wouldn't recommend actually creating negative pressure. The friction alone of skin on lubricated skin is enough to throughly stimulate a dog. Your tongue acts as a wonderful surface for his cock to rub against. Lips squeeze down slightly on the tip of his cock. That little tip you see is the most pleasurable part for them. I have made legs/paws twitch and heard moans of pleasure from correctly stimulating this part.
Every dog is different t and you should be able to read him and what he likes after spending lots of time "blowing" him. What's a better term for just stimulating his dog dick with mouth , because it isn't really"sucking" or "blowing" lol