IGF-I and NEFA concentrations in fetal fluids of term pregnancy dogs

AIM OF THE STUDY. IGF-I and NEFA are listed among the factors playing a role in fetal growth and development in mammals. In humans IGF-I and NEFA amniotic concentrations differ between normally developed fetuses and those affected by intrauterine growth retardation (IUGR) [1,2], but they were not investigated in dogs. The present study was aimed to evaluate IGF-I and NEFA levels in fetal fluids of healthy bitch at term pregnancy and to assess possible differences according to body size. MATERIALS AND METHODS The study enrolled 25 bitches, belonging to several breeds, submitted to elective cesarean section at term. The amniotic and allantoic fluids were collected aseptically from each puppy and stored, after centrifugation, at -20°C until analysis by RIA for IGF-I [3] and by enzymatic-colorimetric methods for NEFA [4]. At birth, the newborn puppies were evaluated for viability by Apgar score [5], maturity, sex, absence of gross malformations, and weight. IGF-I and NEFA concentrations in both fluids were evaluated by one way ANOVA followed by Fisher’s LSD test. RESULTS Only viable, mature, healthy, and with normal birth weight puppies were enrolled. On the basis of bodyweight, the 25 bitches were divided into 3 groups: small, medium, and large size. Mean (±SD) amniotic and allantoic IGF-I and NEFA levels, measured on a total of 73 amniotic and 76 allantoic samples belonging to the 25 litters, are reported in Table 1. Table 1- Amniotic and allantoic IGF-I and NEFA levels (mean±SD) in the 25 litters, divided in small, medium, and large size. IGF-I (ng/ml) NEFA (ng/ml) Bitches (25) Amniotic fluid (73) Allantoic fluid (76) Amniotic fluid (73) Allantoic fluid (76) Small: ≤10 kg (16) 32 ± 13.21a (38) 23 ± 15.01 (41) 44 ± 34.80a (38) 38 ± 27.04a (41) Medium: 11-25 kg (4) 29.8 ± 13.19a (18) 26.5 ± 18.54 (16) 22.7 ± 10.99b (18) 36 ±18b (16) Large: 26-40 kg (5) 43.6 ± 11.46b (17) 19.6 ± 9.49 (19) 14.8 ± 10.74b (17) 11.9 ± 11.22b (19) a,bDifferent superscript within column refers significant differences (p<0.05) CONCLUSIONS In dogs at term, IGF-I concentrations are significantly higher in amnion collected from puppies belonging to large breeds compared to small and medium, suggesting that IGF-I could be an indicator of growth potential in dogs as previously suggested [6]. In both fluids NEFA levels are significantly higher in small breeds than medium and large, as reported in case of IUGR in humans [2] .