TERMINATION OF PREGNANCY IN DOGS BY ORAL-ADMINISTRATION OF DEXAMETHASONE

Dexamethasone was administered orally for 7.5 or 10 d to each of 20 pr egnant bitches beginning at an estimated 28 to 51 d of gestation, usin g 1 of 2 dose regimens. Five bitches were given dexamethasone 3 times a day for 10 d, with the highest dose of 0.2 mg/kg for 5 d and then at progressively decreasing doses of 0.16-0.02 mg/kg for 5 d. The 15 rem aining bitches were given dexamethasone 2 times a day for 7.5 d, incre asing from 0.1 to 0.2 mg/kg over the first 3 administrations, then rem aining at 0.2 mg/kg on Days 2 to 5, and decreasing from 0.16 to 0.02 m g/kg over the last 5 administrations. The side effects, including mild polydipsia and polyuria, disappeared when treatment was discontinued. Depending on the stage of pregnancy, uterine contents were either res orbed or aborted, or both. Pregnancy was terminated within 2 to 16 d a fter the start of treatment in all treated bitches, at 2 to 5 d of tre atment in 2 of 3 bitches treated at 40 to 51 d of pregnancy, and at 0 to 4 d after the end of treatment in most of the 17 bitches treated at 28 to 35 days of pregnancy. Oral administration of dexamethasone appe ars to be a potentially useful pharmacologic treatment for the termina tion of unwanted pregnancy in the bitch.