A rare adverse reaction to deworming dogs with Hellebore is central nervous signs: extreme depression, seizures, etc. Symptoms of poisoning include extreme lethargy, convulsions, drooling, etc. Shivering and lack of energy should be a side effect of the drug. Be sure to observe more for symptoms such as lethargy and convulsions, and take them to the hospital for resuscitation as soon as they are found.
