I have a cat about 6 years old and she is a pretty big cat. We got a dog and i cant find her anywhere in the house and i feel like ive looked everywhere I do not think it went outside. Im starting to get worried
This is not uncommon! Cats are very good at hiding if they don't want to be found. Try looking in dark nooks and crannies with a flashlight that can catch the glow of her eyes. She's not moving or making a sound when you get close, but she is watching. Check behind appliances and large objects, even cracks that you think she'd be too big to fit through.
When you find where she is, close off that room to the dog and set up her food, water, and litter in there, so she can feel safe again. Then she'll have to be slowly introduced until she learns she is safe with the dog.