What makes Canines unique in quadrupedal mammals?

Question

This is someting I discovered on a TV show a while back.
It was something I never really thought over, but thought pretty cool.

Let's see how many other people know it. :P

Something genetic

Answer 1

Dogs are the only animal that becomes hormonally pregnant after every season, even if there was no mating.

Answer 2

The Norwegian Puffin dogs?

That was unforgettable. Dogs are a truly wonderful part of our world, from the turnspit dogs to the Norwegian Lundehunds.
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The Lundehund is a polydactyl (multi-toed) dog. Instead of the normal four toes a foot, the Lundehund has six toes, all fully formed, jointed and muscled. Polydactyl dogs are not terribly uncommon, but in most breeds the extra toes are dew-claws - non-functional vestigial toes, not the fully formed variety of the Lundehund. The dog uses these extra toes to gain purchase and haul itself along in positions where only the sides of its legs are touching the rock, a fairly common occurrence while wiggling through tight spots. They also help the dog gain additional traction while scrambling around on steep, often slippery cliffs.

Lundehund forefeet Also helpful when getting into and out of small caves is the Lundehund's extraordinary flexibility. The Lundehund's forelegs can bend outwards far enough for the dog to lay flat on its chest, with the legs in an approximation of the human arm position. This kind leg flexibility is unheard of, not just in dogs, but in quadrupeds. The only other four-footed mammal that can match it is the reindeer.

The Lundehund's extraordinary flexibility is not limited to the forelegs. The dog's neck and spine are so flexible that it can lay its head back along its own spine, a position most humans couldn't get into under any circumstances short of a broken neck, let alone most dogs. What exactly is going on with the Lundehund's joints isn't certain, but it seems clear that something unique is happening to allow for such unusual joint mobility.




http://www.damninteresting.com/?p=743

Answer 3

Ragapple is correct. This is how a female wolf can suddenly start lactating and raise the pups in the pack if the mother wolf suddenly dies.

Answer 4

Give us a clue - is it something anatomical, physiological or behavioural?

Chalice

EDIT: Oh that - pseudopregnancies then? My money's on that answer too!