When this is given to canines (and again this is done very rarely), the dose is small, just 5 mg for each one pound of body weight. With a typical adult Chihuahua, being only 5 lbs., the recommended dose would be 25 mg every 12 hours.
Regular strength Tylenol contains 325 mg of acetaminophen in each tablet; so dosing would be 1/13 of a pill and obviously too tiny to be properly divided at home and given to the dog.
You may wonder if it would be better to give infant or children's strength Tylenol to a Chihuahua instead, which comes in a liquid form; however this is not recommended either.
The infant strength formula, which is one of the lowest dosing available, contains 160 mg of acetaminophen in each 5 ml; an adult Chihuahua would need less than 1 ml per safe dosing instructions. There is a children's 'meltaway' formula, which is a flavored chewable tablet that contains 80 mg of acetaminophen, however it would be difficult to properly divide this due to its consistency.
Any amount over the 5 mg per 1 lb. of body weight
is considered dangerous and any amount over 50 mg per pound of body weight is considered toxic.
If a Chihuahua were to accidentally ingest Tylenol or another medication that contained the active ingredient of acetaminophen, signs of poisoning include: trouble breathing, discolored gums, a swelling of certain body parts (most notably the face, neck or legs), jaundice (yellowing of the eyes) and/or vomiting. This is considered an emergency and treatment is needed immediately.
So as you can see even these lower-dose products contain too much acetaminophen to be considered safe for canines and should not be given to a Chihuahua puppy or dog unless the veterinarian has prescribed this; there are better options and we will discuss those ahead.