Why would your cat start staggering and shaking suddenly?

Like humans and most other animals, cats depend on their inner ear canals for balance. A lack of equilibrium can be caused by an ear infection. Any infection, in fact, if it is severe enough, can affect equilibrium. Additionally, a cat uses his tail as an active weight to aid his balance; a disease that affects the control of his tail, or the traumatic loss of a significant part of his tail, can hinder his balance.