An adult egg-carrying tick is one of the more disgusting things to see on a dog (top right one in [1]). It looks like a pimple or some weird skin blister if you don't know what you're looking at. And the removal can look awfully bloody depending on its location. Ticks are probably one reason dogs evolved to like being petted so much - it helps the owner find and remove parasites like this early.

[1] https://news.psu.edu/sites/default/files/styles/threshold-76...