Chihuahuas are prone to shaking because of their small size and fast metabolism. In most cases, Chihuahua owners find that putting their dog in a sweater or offering a warm blanket during cold weather helps reduce shaking. Common causes for trembling include excitement, cold weather, anxiety, and pent-up energy. Underlying health conditions such as canine distemper, General Tremor Syndrome (GTS), and fever may also manifest through tremors.