A 'Whelp' is the term for a young dog or wolf. 'To Whelp' - 'To give birth to..' When a puppy/cub is part of a litter still under the care of the dam(mother) it is one of the whelp.
If I'm not mistaken it's a dogs cry. Like a persons yelp. Or a babies cry. It's the sound they make when they are hurt or sad
One definition is the process of giving birth by a female dog.