This powerful narcotic is more in favour with amateur horse doctors than with veterinary surgeons. The manufactured tobaccos are very variable in medicinal power, and when required as a drug Virginian shag is usually selected, as containing more resinous and albuminous matters, which in other kinds are more or less removed by partial fermentation.
Externally applied it is more or less irritant. Internally it causes muscular relaxation, and in this way acts as an antispasmodic in bowel and other affections.
It is sometimes given to destroy worms in the intestines, and a small plug of it introduced into the rectum with the view of getting rid of "fundament" bots and other parasites which infest the terminal portion of the bowel. Tobacco smoke injected into the rectum by means of suitable apparatus appears to give relief in some cases of colic.
Grooms and other horsy persons introduce tobacco into the sheath of horses and the vagina of mares under the impression that it incites them to urinate. If it does so, it is only by its local irritant effect upon the parts.