It’s safest not to assume that your cat has started meowing more because she has become more demanding. More vocalizing than usual means something’s wrong. It could be behavioral — fear, grief for the loss of another pet, even boredom — or it could be medical. Medical causes for an increase in vocalizations include anything from a respiratory infection to hearing loss (which may be expressed by yowling rather than meowing). Persistent vocalizations that hadn’t been going on previously could also be an indication of pain.