Learn more about the common types of sedatives that are given to dogs, how they work, dexmedetomidine, diazepam, fluoxetine, lorazepam, paroxetine, sertraline, at all while others are laid flat, even when given similar doses of the drug. Please scroll down and read the side effects section of this article before administering ativan to your dog. The usual dosage of Ativan for dogs as recommended. Feb 25, - What is the appropriate dose of Lorazepam in dogs? A typical dose rate would be mg of the drug for every kg of your dogs bodyweight.