This section is from the book "The Farmers Ready Reference Or Hand Book Of Diseases Of Horses And Cattle", by S. C. Orr. . Also available from Amazon: The Farmer's Ready Reference;.
Always first determine what the disease is, then select the remedy best suited or recommended for that disease. When a selection is once made give the prescribed dose and then wait a sufficient length of time for the result, and do not get impatient and repeat the same or give something else that some disinterested bystander recommends as a "sure cure." Many horses are killed every year by over-dosing that, if left alone, would have gotten well without any treatment. Medicines are always most conveniently given in the food or drink, when it can be done; but some drugs have such a disagreeable odor or taste that no horse will take them in this way. Some medicines, as aloes, are best made into a ball and placed well back on the tongue. Powders can be put into a large spoon and placed well back on the tongue, and the head held up until the medicine becomes mixed with saliva. But as the most common way of giving medicine is by drenching, we will describe the best plan of performing that operation: First, always drench through the mouth, and not through the nose. Second, do not pull the horse's head up with the halter, but take a rope ten or more feet long; tie a loop a foot long in one end; now pass this loop down inside of the nose-piece of the halter and place it in the animal's mouth; now throw the other end over a beam, or a limb of a tree, and pull on it till the head is as high as you want it; now, while an assistant holds this rope, you can open the side of the mouth with one hand, while with the other you insert the neck of the bottle or drenching horn and pour the medicine in, a little at a time, to avoid choking the horse. This holds the head up by the upper jaw, while the lower jaw is left free to work up and down and work the medicine back. The tongue should never be pulled out or held by the hand, as it does no good and increases the danger of choking. All medicines to be given in drenches should be well diluted and, if of an irritating nature, they can be more safely given in raw linseed oil, sweet milk, or gruel of some kind. The dose should also vary to suit the condition and temperament of the animal. An old and debilitated patient, or one with a highly-nervous temperament, will require a smaller dose than one in fair flesh or with a sluggish temperament. The doses, as given in this work, unless otherwise stated, are always intended for grown animals. By observing the following table the dose for any age may be easily ascertained:
3 or more years
2 or more years
1 1/2 years
As facilities are not always at hand for accurate weight or measurement of doses, an approximate measure may be attained by the following table:
A teaspoonful equals 1 fluid drachm;
A tablespoonful equals half a fluid ounce.
Roots or Barks, Powdered -
A teaspoonful equals two-thirds of a drachm;
1 1/2 tablespoonfuls equal half an ounce.
Powdered Herbs -
3 teaspoonfuls equal 1 drachm;
3 tablespoonfuls equal half an ounce.
Salt, Saltpetre, Sulphur, Etc -
A teaspoonful equals 1 drachm.
Sugar of Lead, Sulphate of Zinc, Etc. -
A teaspoonful equals 1 1/2 drachms.