IGF-I fetal fluids concentrations in term pregnancy dogs

INTRODUCTION AND AIMS. Fetal growth and well being are regulated by several factors. Among them, IGF-I are recognized as to be involved in intra uterine growth retardation (IUGR) in humans, and different IGF-I have been detected in amniotic fluid from normal developed and IUGR babies (1). Amniotic IGF-I values are also related to birth weight in humans (1). Few studies focused on fetal fluids composition in dogs and the concentrations of IGF-I in fetal fluids during normal pregnancy still remain uninvestigated. In addition, because of the wide heterogeneity of body size among several dogs breeds, it could be interesting to evaluate possible differences among fetal fluids IGF-I concentrations in relation to breed size. The aim of the present study was to evaluate the IGF-I fetal fluids concentration in term pregnancy dogs and to assess possible differences in relation to breed size. MATERIALS AND METHODS. The study was performed on 25 bitches submitted to elective Caesarean section at term of pregnancy. During surgery, the amniotic and allantoic fluids were aseptically collected and stored at -20° C until analysis by RIA (2). The neonates were also evaluated for viability by APGAR score (3), for maturity by hair distribution and completeness, for sex, for absence of gross physical defects and weighted before nursing. IGF in amnion and allantois in bitch with different breed size (small size, bodyweight ≤10 kg; medium size, bodyweight 11-25 kg; and large size bodyweight 26-40 kg) was tested using a one way ANOVA followed by Scheffè post-hoc test where required. RESULTS. A total of 61 amniotic and 76 allantoic samples were collected from bitches 2-8 years old, 2-7 parity, with litter-size ranging between 1 and 7. All the neonates were alive and viable, healthy, mature, without physical defects and with bodyweight falling in the range for the belonging breed. Mean (± SD) IGF-I concentrations was significantly higher in amniotic samples then in allantoic fluid (p<0.01). IGF-I concentrations in amniotic fluids were significantly lower in small and medium size bitches compared with large size breeds (table 1). No significant differences were found in allantoic fluids in the three classes. A significant effect of the bitch (p=0.008), but not of the puppy, was found about the IGF content in both fetal fluids. Table 1- Mean ± SD IGF-I concentrations in amniotic and allantoic fluids in the three classes of breed size dogs. IGF-I (ng/ml) Breed Size (n of bitches) amniotic (n of samples) allantoic (n of samples) Small size (16) 32.7 ±13.29a (36) 22.9 ± 15.01 (41) Medium size (4) 31 ± 15.19a (18) 30.7 ± 20.44 (16) Large size (5) 43.6 ± 11.46b (17) 19.6 ± 9.49 (19) In the same column, different superscript differ significantly (a/b, p<0.05) DISCUSSION. The results showed that IGF-I concentrations are higher in amniotic compared to allantoic fluid, and significantly higher in amniotic fluids collected from fetus belonging to large breed as compared to small and medium size breed, suggesting that IGF-I could be an indicator of growth potential in dogs, as previously reported by (4) in serum.