my girl Lil Bit is a 2 year old adult and has always had a high pitched bark. Now all of a sudden it has changed from her usual high pitch to a very deep pitch like her dad's. The transition was over 1 day and it sounded like a teenaged boy's voice changing. She isn't acting lethargic, she is eating well, the weather changed from warm and dry to cold and wet. I haven't heard any cough and her collar is not tight on her. Should I be worried, like maybe she has a cold? Could an adult dogs bark change without provocation or should I check her out at the vet?