Pet euthanasia is most often administered through a sequence of two injections: a sedative followed by a barbiturate, as reported by PetMD. The goal of the first injection is complete sedation and anesthesia. The second injection is a deliberate overdose to induce cardiac arrest and death in the animal.
In the euthanasia of domestic pets, the anesthetics used can vary depending upon expense or availability. Telazol and Propofol are commonly chosen by vets for their complete sedative and pain-relieving effects, as indicated by PetMD. Ketamine is also highly effective.
For the second injection, the most commonly used drug is pentobarbital, according to PetEducation.com. An overdose is administered after the pet is anesthetized, which leads to cardiac suppression and death. The drug usually has a very rapid effect, working in five to 10 seconds for most animals.