Sopie Helen Is Unable To Walk Today

We have had nineteen dogs. Sophie Helen, our black cocker spaniel, has been with us for eleven years; not our record, but close. Today she cannot lift her back end. Is it her weight? Her age? Are her legs too weak? Has she had a stroke? I carry her all around inside and outside. We discuss options. Wonder if she needs to be put down. I leave her outside in the grass. An unfamiliar vehicle enters the driveway. Sophie Helen crosses the twenty foot driveway, bounds onto the porch, and races through the slider to warn us of the intruders. We are amazed and consternated. She is back in her sitting state, once again unable to walk. Was she given extra streaks of adrenaline when she thought we were in danger? It is a puzzle