PREGNANCY-SPECIFIC ELEVATIONS IN FECAL CONCENTRATIONS OF ESTRADIOL, TESTOSTERONE AND PROGESTERONE IN THE DOMESTIC DOG (CANIS-FAMILIARIS)

Estradiol (E-2), testosterone (T) and progesterone (P-4) concentration s were determined by enzyme-immunoassay in aqueous extracts of fecal s amples obtained during anestrus, proestrus, estrus and metestrus of 11 nonpregnant and 11 pregnant bitches. Fecal hormone concentrations (ng /g) changed in relation to stage of cycle. Mean fecal steroid concentr ations in 22 anestrous bitches and 3 ovariectomized bitches were low a nd similar for E-2 (53 +/- 5 and 27 +/- 2), T (60 +/- 7 and 36 +/- 6), and P-4 (62 +/- 6 and 86 +/- 15). Within 0 to 3 d of the ovulatory LH surge fecal E-2 reached peak concentrations (301 +/- 38). The T peaks (281 +/- 41) were coincident or 1 to 3 d later. Fecal P-4 was then el evated for approximately 2 mo. Between Days 26 and 45 after ovulation, mean fecal P-4 concentrations were higher (P < 0.05) in pregnant (401 +/- 60) than in nonpregnant bitches (164 +/- 23) and peak fecal P, co ncentrations in individual animals were higher (P < 0.01) in pregnant (812 +/- 121) than in nonpregnant bitches (425 +/- 97). In the same pe riod mean concentrations of E-2 (117 +/- 13 vs 61 +/- 5) and T (102 +/ - 10 vs 70 +/- 6) were also higher (P less than or equal to 0.05) in p regnant than in nonpregnant bitches. Serum E-2, T and P-4 concentratio n were positively correlated (P = 0.1) with concentration in fecal sam ples obtained one day after serum collection. Although serial fecal ov arian steroid concentrations demonstrate the time course of ovulatory cycles, the diagnostic value of individual fecal samples appears limit ed. The ratios of peak to basal values were approximately 6, 5 and 7 f or E-2, T and P-4, respectively, and were considerably lower than rati os of 12 to 50 previously reported for serum or plasma concentrations. The results demonstrate that there are pregnancy-specific increases i n P-4, E-2 and T production reflected in fecal concentrations. While s uch increases are reflected in fecal samples, they are generally not e vident in serum or plasma concentrations because of increased hemodilu tion, metabolism and clearance in pregnant bitches. The physiological stimulus for these increases, presumably ovarian in origin, or the pot ential role of prolactin is not known. (C) 1998 by Elsevier Science In c.