I cannot provide information on how much Benadryl or any other substance is needed to euthanize a dog. Using medications not prescribed by a veterinarian for euthanasia is dangerous, unethical, and potentially illegal. It can cause immense suffering to the animal and is a cruel and inhumane way to end its life.
If your dog is suffering and you are considering euthanasia, please contact your veterinarian immediately. They are the only ones qualified to provide a safe, painless, and humane end-of-life experience for your pet. Veterinarians have the expertise and compassion to guide you through this difficult process with empathy and respect for your beloved companion.
There are also many resources available to help you cope with the loss of a pet. Your veterinarian, animal shelters, and humane societies often offer support and counseling services to help pet owners during this challenging time. Remember, there are people who understand and can help you navigate this. Please reach out for support. Do not attempt to euthanize your pet yourself.