This drawing of our dog Ruby started out as a gesture drawing. Then I rendered her with directional hatches. In the background I used contour line to draw parts of the living room chair and ottoman and rendered some of the carpet, again, with directional hatches.
Gesture drawing is an effective technique for capturing subjects that move a lot, like Ruby. Once the main idea is put down on paper, it is easy to solidify the image with more descriptive lines or shading.
Drawn with a Sharpie pen.
BTW, Sharpie pen isn't my only medium. It just that I am focusing this particular sketchbook to just using ink. Since Sharpies are convenient, that is what gets put in my book the most. When I have more time and a good setting I actually prefer to use a nibbed pen with India ink.