Most domestic dog breeds have two estrus cycles a years, while wolves and a few “primitive” dog breeds have only one. Tibetan Mastiffs and Basenjis are two such breeds, but a third, the Carolina Dog, has an even more peculiar trait.

Female Carolina Dogs come into season three times in rapid succession, then enter a normal breeding cycle when there’s an abundance of puppies.  It’s theorized this adaptation allowed the breed to quickly recover its numbers, or to continue to produce young following a major disease epidemic or natural disaster. Even more unusual is that 98% of females dig “snout pits” between September and January, or shortly after whelping.  These pits are described as small holes the dogs dig out of the dirt with their snouts.  Reasons are open to speculation. Possibly the dogs are looking for a buried food source, or are getting at nutrient rich clay.

Carolina Dog by Debra Howard. This poster is available here. You can find more work by this artist here