Termination of pregnancy in dogs by oral administration of dexamethasone

Dexamethasone was administered orally for 7.5 or 10 d to each of 20 pregnant bitches beginning at an estimated 28 to 51 d of gestation, using 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 remaining bitches were given dexamethasone 2 times a day for 7.5 d, increasing from 0.1 to 0.2 mg/kg over the first 3 administrations, then remaining at 0.2 mg/kg on Days 2 to 5, and decreasing from 0.16 to 0.02 mg/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 resorbed or aborted, or both. Pregnancy was terminated within 2 to 16 d after the start of treatment in all treated bitches, at 2 to 5 d of treatment 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 appears to be a potentially useful pharmacologic treatment for the termination of unwanted pregnancy in the bitch.