Not only do dapples echo the pattern of capillary clusters, but other vascular details are visible on dappled horses.
In the previous post, a thermal image showing capillary clusters explained the look that dappling has. It's not just those clusters, however, that are visible in the dappling pattern. There are other areas where the vascular patterns are reflected in the lighter areas of a dappled coat.
One of the most consistent is the area along the jugular groove. It's visible on the neck of the grey mare pictured at the top of the post and this grey hunter pony.
The same area is often paler in horses that have sooty overlay dappling or even dappling from clipping.
For artists doing finish work in the collectibles industry, nothing will check proper anatomy on a neck like trying to replicate this characteristic shape behind the cheek - and finding the "groove" isn't in the right place!
Another area where the veins produce a lighter pattern—particularly in greys—is the backs of the ears.
One of my earliest memories of getting photos for painting references was talking my way up onto a large hitch of Percherons so that I could take pictures of the backs of their ears. I was fascinated by the way white lines traced the outline of the veins. Fortunately, the raised viewing area over the practice ring at the Tryon Equestrian Center makes getting pictures like the one below much easier!
The other area that shows a distinctive vascular pattern is the upper parts of the legs. On grey horses, this is especially visible around the gaskins and stifles.
The same veins are visible on the legs of this gold champagne, only in reverse.
Here the vein on the back of the ear and the stifle are visible on a Foxtrotter from an earlier post on reversed dapple roans.
I've been talking about dappling as a pattern in the last few posts. Normally in horse color, a "pattern" refers to areas of white. Used more broadly, it can also mean the spatial arrangement of color without regard to the pigments involved. In a sense, what is meant is a template of sorts that directs the coloring. As the last few posts have shown, the "template" for dappling comes from the vascular system. There is another template that features prominently in horse color. That is what is sometimes called "the points"—mane, tail and legs—and that is a puzzle that has perplexed me for a while. I'll save that for the next post.