All of these products can result in stomach upset and other more serious symptoms including muscle tremors, weakness or paralysis of the hindquarters, vomiting, elevated body temperature, and rapid heart rate. (happytailsspa-blog.com)
High levels of theobromine (theobromine poisoning), can cause muscle tremors, seizures, an irregular heartbeat, internal bleeding, and / or heart attack. (stewartpet.com)
People with Parkinson's disease experience muscle tremors and rigidity because something kills off the brain cells that normally make the movement - coordinating chemical dopamine. (discovermagazine.com)