I've noticed that the outlines with sheep and cows (though more faint, not sure about chickens or pigs) were white. Can appear on I believe all colors of sheep with wool, it's more noticeable on black sheep but very hard to see it on white sheep. It appears on evey corner of their body including cows. (Though not sure if been sheered, not including cows.)

Cows and sheep don't cause anything bad with their weird white outlines.