The experiments were carried out on well-fed adult dogs and on puppies,
kept under observation for some time before the drug was administered.
Only those manifesting no signs of abnormality were used for these
tests. Caffein was given by mouth mixed with 10 to 20 grams of meat,
or subcutaneously in 2 per cent aqueous solution. The young animals
received caffein dissolved in milk. The determination of the minimum
toxic or fatal doses when the drug was fed presented considerable
difficulty, as in many instances the ingestion of the drug was closely
followed by vomiting.