The same thing happened to a cat of mine, but because she was inside, I saw it right away. (She wears a collar indoors because she's easier to find that way...the bell lets me know where she is.)
My cat has survived outside for over ten years. She is half Persian, half Siamese, a hunter, and more wild than a lap kitty. Thirteen pounds of independence.
She WILL NOT, by choice, stay inside the house. She will come about four feet inside the door, then, not liking the temperature, or the various smells inside; she then makes a dash for the door. - She has her own slightly heated room where I keep her beds, favorite food, and water; then she comes to the back door for her tuna and other treats at night. If she doesn’t show up, I call until she does show up. Here, she is persnickety. She is also mean as they come, ruling the two big dogs and other wild stuff around the place with a slashing paw across the face of anyone who crosses her.
Funny, the dogs love her in spite of her snotty personality. She is the way she is, and would be most miserable, rebellious and LOUD if I dared to cross her. She loves me, but on the rare occasion she allows me to pet her, I have so much static electricity, and so does she, that when I touch her, I shock her. Her annual visit to the vet is tolerated well considering.