Excitement, old age, pain and nausea are all causes of trembling in dogs, according to WebMD. Trembling or shivering may be a sign of something serious, such as an injury, kidney disease or poisoning.
Owners should note any symptoms that accompany trembling, such as limping, vomiting or diarrhea, and consult a veterinarian as soon as possible to rule out a serious condition, advises WebMD. Distemper, a condition that can grow serious if left untreated, is a potential cause of trembling. Other symptoms of distemper include coughing, fever, and discharge from the nose or eyes.
Poisoning is another possible cause of trembling in dogs, reports WebMD. If a dog swallows a toxin such as chocolate, sugar substitute or cigarettes, it may also experience symptoms such as diarrhea, drooling, seizures and disorientation. The dog requires immediate veterinary evaluation.