
Having a litter can upset the normal season cycle, much as with mine, they have gone longer between seasons, rather than the opposite.
The point about a post-whelping discharge is worth considering - again I've had some who have done this for quite some weeks although with those of mine who had C.Sections, that didn't last very long as all the birthing material had been removed, with the Section. Obviously if you are worried at all, speak to your vet.