Questions & Answers about חיית המחמד ישנה בכלוב ליד המלונה.
חיית המחמד is the normal Hebrew way to say the pet. It is a construct chain (called סמיכות), literally something like the animal of affection/fondness. In modern Hebrew, this whole expression simply means pet.
Using just חיה would mean animal, not specifically pet.
Because חיית is the construct form of חיה.
A very common pattern in Hebrew is that a feminine noun ending in ־ה changes to ־ת when it comes before another noun in a construct chain:
- חיה = animal
- חיית = animal of ...
So חיית המחמד = the pet.