Katy was pregnant to Cal and now Sarah was pregnant to Katy. A real interbred family. Katy had tried to use birth control pills, but they had been designed for normal pregnancies, not half dog/half human pregnancies. Birth control for dogs was limited usually being surgical and permanent. There wasn't the interest for animals like humans. She had vomited them up, given the circumstances that had led to her pregnancy she felt that she couldn't use modern medicine to remove the baby.
But she was terribly alone and she wanted to spread her disease, so she picked her exotic sister. She could hear Sarah now vomiting up the pills she (like Katy a fortnight before) had purchased to abort her baby only to find the pills reacted badly with her new biology. She was now enduring morning sickness. Together they would both support each other as sisters and later aunties in their cursed mother-hoods.