This section is from the book "The Dogs Of Great Britain, America, And Other Countries. Their Breeding, Training, and Management in Health and Disease", by John Henry Walsh (Stonehenge). Also available from Amazon: The Dogs Of Great Britain, America And Other Countries.
If the dog is small, take him on the lap, without harshness, and if inclined to use his claws, tie a coarse towel round his neck, letting it fall down in front, which will muffle them effectually; then with the finger and thumb of the left hand press open the mouth by inserting them between the teeth, far enough back to take in the cheeks. This compels the mouth to open from the pain given by the pressure against the teeth, while it also prevents the dog from biting the fingers. Then raising the nose, drop the pill as far back as possible, and push it well down the throat with the forefinger of the right hand. Let go with the left hand, still hold up the nose, keeping the mouth shut, and the pill is sure to go down. Two persons are required in administering a pill to a large dog, if he is at all inclined to resist. First, back him into a corner, then stride over him, and putting a thick cloth into his mouth, bring it together over the nose, where it is held by the left hand; the right can then generally lay hold of the lower jaw. But if the dog is very obstinate, another cloth must also be placed over the first, and then as they are drawn apart, an assistant can push the pill down.
Very often a piece of meat may be used to wrap the pill in, and the dog will readily bolt it; but sometimes it is desirable to avoid this, as it may be necessary to give the medicine by itself. Even large dogs, however, are seldom so troublesome as to require the above precautions in giving pills, though they, as a general thing, obstinately refuse liquid medicine when they have tasted it once or twice.