Modulation of the biochemical composition of amniotic and allantoic fluids as a control mechanism of feline foetal development

Canine and feline foetal fluids: Volume, hormonal and biochemical characterization during pregnancy

BACKGROUND AND OBJECTIVES

This study aimed to evaluate the volume, the concentration of steroid hormones, and biochemical composition of the foetal fluids at different gestational ages in dogs and cats.

METHODS

Following the ovariohysterectomy, the allantoic and amniotic fluid samples were collected from pregnant bitches and queens and were assigned to different groups according to their gestational age.

RESULTS

The canine and feline allantoic fluid volume increased during pregnancy, reached its maximum values on days 40-49 and then decreased. The canine and feline amniotic fluid volume increased steadily by the last days of pregnancy. In spite of significant changes of sex hormones in the foetal fluids, their concentration and ratios were not significantly different between male and female fetuses. The canine amniotic cortisol concentration increased until days 40-49 and decreased significantly afterwards. The maximum cortisol concentrations in the feline allantoic and amniotic fluids were observed on days 50-60 and 40-49, respectively. During the canine pregnancy, the concentrations of calcium, phosphorus, chloride, sodium, triglyceride, cholesterol, total protein, albumin and the activities of aminotransferase (AST), alkaline phosphatase (ALP), amylase and gamma-glutamyl transferase (GGT) in the amniotic fluid were higher than the allantoic fluid. The magnesium, potassium, lactate dehydrogenase (LDH) activity, creatine and lipase were higher in the allantoic fluid. In the feline allantoic fluid, potassium, magnesium, phosphorus, creatinine, albumin and glucose concentrations and the activities of creatine kinase (CK), GGT, LDH and lipase were higher. The ALP, AST activities, sodium and calcium concentrations were higher in the amniotic fluid (p < 0.05).

CONCLUSION

Volume of foetal fluids was determined in dogs and cats. Concentration of sex hormones did not different between male and female fetuses.

Biochemical factors affecting newborn survival in dogs and cats

The importance and implications of small animal neonatology were underestimated until recent times. Despite the recent increasing interest for this branch of veterinary medicine, however, perinatal mortality rates in canine and feline species remain high, representing an important challenge for the clinician. In this perspective, the prompt identification of newborns requiring additional and tailored assistance becomes a key to reduce the perinatal losses in small animals. To achieve this goal, clinical and laboratory findings must be carefully evaluated. This paper focuses on biochemical parameters and their reported influence on neonatal survival, guiding through the evaluation of canine and feline newborn laboratory analyses, with a thorough discussion about the use of different biological material in these subjects. Beside blood, other biological material, such as urines and fetal fluids proved to be interesting for the identification of possible prognostic markers, thanks also to their easy and safe collection. However, the correct reading-through the results must consider many variables such as type of delivery, anesthesia protocol in case of Caesarean section, age of the newborn at samples collection, and for blood analysis, also the type of blood, site of collection, modality of collection and storage must be considered. Notwithstanding the recent progress in literature, for most of the parameters more research is needed to define cut-off values with certainty.

Evaluation of Biochemical Composition of Amniotic and Allantoic Fluids at Different Stages of Pregnancy in Queens

Simple Summary

Fetal fluid contents influence growth and development, fetal wellbeing and a protection mechanism for the fetus itself. Very little is known about the composition of fetal fluids during pregnancy in cats and about changes in contents that occur throughout gestation. In this study, initial results regarding the biochemical composition of fetal fluids are provided. A comparison with maternal serum was also performed. A complete understanding of trends can be helpful for the early detection of some pathologies during pregnancy, such as in humans and mares.

Abstract

Fetal fluid contents have functions in protecting fetuses and are essential for fetal development and maturation. However, little is known about the exact physiological functions of fetal fluids in fetal development, as well as the changing composition throughout the gestational period in cats. In this study, the biochemical composition of amniotic (AMN) and allantoic (ALL) fluids was investigated, as well as in the maternal serum of pregnant queens. Eighteen queens were included in this study and assigned to six different groups, D₂₀, D₂₅, D₃₀, D₄₀, D₄₅ and D₆₀, according to the gestational stage of fetal development. A total of 44 amniotic and 37 allantoic samples were collected. Fetal fluids contained lesser concentrations of alanine aminotransferase, albumin, cholesterol, triglycerides, creatine kinase, amylase, total protein and globulin than maternal serum. Other variables, such as aspartate aminotransferase, gamma-glutamyl transferase, bilirubin and alkaline phosphatase, were in different concentrations at specific stages of gestation when compared to maternal serum. There were no differences between fetal fluids and maternal serum for lactate dehydrogenase, urea, lipase or glucose concentrations. There were greater concentrations of creatinine in amniotic fluid than in allantoic fluid or maternal serum. Based on the results of this study, fetal fluids do not accumulate as a result of the simple filtration of maternal blood, but rather, the fetus produces many of these components as a consequence of organ development and maturation.

Clinical Trial on the Usefulness of On-Site Evaluation of Canine Fetal Fluids by Reagent Test Strip in Puppies at Elective Caesarean Section

Simple Summary

In veterinary medicine, the availability of an easy tool for the immediate evaluation of biological fluids’ composition on site is desirable and beneficial as a first-line diagnostic instrument in many instances and in several animal species. The aim of the present study was to assess the usefulness of reagent urinary test strips marketed for urines for the on-field evaluation of fetal fluids’ composition in newborn dogs at elective caesarean section. From surviving newborns, a collection of 113 amniotic and 107 allantoic samples was performed, and 8 amniotic and allantoic fluids were collected from non-surviving newborns. All the fetal fluids were assessed by urinary test strips within 5 min from collection. Significant differences were found for both types of fluid between surviving and non-surviving puppies, and between medium/large and small-sized puppies. Differences were also depicted between amniotic and allantoic fluids within the surviving group. These results seem to suggest that the on-site analysis of fetal fluids’ composition by reagent test strips could represent a first-line tool for the evaluation of puppies and for the quick identification of puppies requiring special monitoring and assistance.

Abstract

The reagent urinary test strips (TS) marketed for urines represent the first-line diagnostic tool in many instances. Therefore, the aim of the study was to assess the usefulness of TS for the on-field evaluation of fetal fluids’ composition in newborn dogs at elective caesarean section. Of a total of 137 puppies born at term, 127 survived and 10 did not survive. One hundred and thirteen amniotic and 107 allantoic samples from surviving newborns were collected, and 8 amniotic and allantoic fluids were collected from the non-surviving newborns and assessed by strips. Significantly lower amounts of amniotic glucose and higher amounts of amniotic and allantoic nitrites, amniotic protein, allantoic urobilinogen, and amniotic bilirubin concentrations were found in non-surviving when compared to surviving newborns. In the surviving ones, higher specific gravity and bilirubin concentrations, and lower pH, were found in allantoic than in amniotic fluids. Higher amniotic and allantoic glucose concentrations, higher amniotic and allantoic pH, and lower amniotic and allantoic protein concentrations were found in medium/large- than in small-sized puppies. The TS allowed the quick evaluation of fetal fluids in puppies at birth. The differences between surviving and non-surviving puppies seem to suggest that the on-site analysis of fetal fluids’ composition by TS could represent a first-line diagnostic tool in the field of canine neonatology, allowing the quick recognition of puppies needing assistance as a complementary tool for clinical evaluation.

Some more about dogs: Proteomics of neglected biological fluids

We report in this manuscript what is known about the protein makeup of a selection of biological fluids in the domestic dog. The samples we review - amniotic and allantoic fluid, seminal fluid, saliva, bile, synovial fluid, tears - are still very poorly characterized in this species. For some of them we can present results from our own, mainly unpublished experiments. SIGNIFICANCE: The dog is one of the most widespread companion animals, and also of medical relevance as model species for some human diseases. Still, investigation of body fluids other than serum and urine is not so commonly undertaken, although - like in humans - also these sample types may have potential for diagnostic purposes. We compile published data about proteomes of fetal fluids, seminal plasma, saliva, bile, synovial fluid and tears, enriched by some yet unpublished data of our own (proteins of amniotic and allantoic fluid, tears). Closing gaps in our knowledge on dog proteins will further our understanding of (patho)physiological processes.

Gestational Age-Dependent Fetal Fluid Dynamics in the Ovine Developmental Model: Establishment of Surrogate Markers for the Differentiation of Stem Cell Origin

The ovine developmental model represents the standard in vivo model for studies involving maternofetal physiology, amniotic fluid (AF) research, and fetal cell therapy prior to human clinical use. Although being close to the human fetal anatomy, 2 separate extraembryonic fluid compartments remain during gestation, known as the amnion and the allantois. A clear distinction between AF versus allantoic fluid (AL) is therefore indispensable for correct scientific conclusions with regard to human translation. In the presented study, the biochemical composition of AF and AL was evaluated in ovine gravid uteri postmortem (n = 31) over the entire gestation. Four parameters, consisting of Na+, Cl-, Mg2+, and total protein, have been found to allow for specific discrimination of the 2 fetal fluids at all gestational phases and therefore as potential surrogate parameters for gestational age. In addition, volumetric changes of the developing fetus and the 2 fetal fluid cavities were analyzed by contrast-enhanced computed tomography (n = 12). AF showed a significant, linear volumetric increase over gestation, whereas AL volume maintained relatively static independent of gestational age. These results serve as a basis for future studies by providing surrogate markers enabling a reliable distinction of isolated fetal fluids and contained cells in the ovine developmental model over the entire gestation.

Effect of maternal metabolism on fetal supply: Glucose, non-esterified fatty acids and beta-hydroxybutyrate concentrations in canine maternal serum and fetal fluids at term pregnancy

The progressive adaptations in carbohydrate and lipid metabolism during canine pregnancy are reflected in the concentrations of glucose, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB). The levels of these metabolites in the bitch likely affect fetal concentrations and the composition of amniotic and allantoic fluids (AMF and ALF, respectively). We studied 31 canine parturitions (Cesarean sections) and found that glucose, NEFA and BHB concentrations were significantly higher in maternal serum than in AMF or ALF. Glucose levels in maternal serum, AMF and ALF were closely related (R² ≥ 0.821, P < 0.0001) as well as serum and AMF BHB levels (R² = 0.661, P < 0.0001). In maternal serum, increases in NEFA were associated with increased BHB, and both were negatively related to glucose (P ≤ 0.010). To estimate the effect of the metabolic burden of pregnancy, we evaluated these variables in relation to the dam's body weight and to the ratio of litter weight to the dam's body weight (LW/BW). Maternal serum glucose was not influenced by LW/BW, but it was lower in small than in large/giant bitches. Small breed dogs and those with >10% LW/BW had significantly higher serum NEFA and BHB concentrations. Glucose in AMF and ALF was independent of LW/BW (P ≥ 0.399). AMF NEFA was lower and BHB higher, if LW/BW was >10% (P ≤ 0.048). In conclusion, the extent of the metabolic load of pregnancy in bitches depends on breed size and on the ratio of litter weight to dam's body weight. Maternal concentrations of glucose, BHB and NEFA determine the concentrations of these metabolites in fetal fluids.

Biochemical composition of fetal fluids in at term, normal developed, healthy, viable dogs and preliminary data from pathologic littermates

A proper canine neonatal assistance, required to reduce the high perinatal loss rate, imply a full knowledge about the fetal-to-neonatal physiology. Because fetal fluids play an important role throughout mammals pregnancy, influencing fetal growth and development, fetal well being, and contributing to guarantee the most suitable environment for the fetus, the knowledge about fetal fluids biochemical composition is of major importance. At first, the biochemical composition of fetal fluids collected by normal developed, healthy and viable newborns, is necessary to depict the normal features, and represent the first step for the further detection of abnormalities associated to fetal/neonatal distress and useful for the early identification of newborns needing special attention, immediately after birth. The present study was aimed to define the biochemical composition of amniotic and allantoic fluids collected from fetus delivered by caesarean section at term of pregnancy. To reduce the possible confounding effect of maternal labor or troubles at parturition, fetal fluids were collected only from puppies born by elective caesaeran section, at term of normal pregnancies. Fetal fluids from 76 puppies, 70 normal and six pathologic newborns, born by elective caesarean section were collected and analyzed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, lactate dehydrogenase (LDH), creatine-kinase (CK), alkaline phosphatase (ALP), creatinine, urea, amylase, lipase, gamma-glutamyl transferase (γ-GT), triglycerides, cholesterol, total proteins, albumin, globulins, glucose, magnesium, potassium, chloride, sodium, calcium, phosphorus and osmolarity. No significant differences were found between biochemical composition of amniotic or allantoic fluid in normal and pathologic newborns, maybe due to the small number of the pathologic puppies. Although some correlations between the two fluids were found (albumin, phosphorus, glucose and triglycerides), the results showed significant differences between the amniotic and allantoic biochemical composition (for all the parameters, except of alanine aminotransferase, triglycerides, cholesterol, albumin, amylase and glucose), suggesting that diverse sources could concur to the final composition of each fluid. A wide variability within and among litters was found for both amniotic and allantoic biochemical composition, and for some parameters an influence of breed body size (amniotic amylase, cholesterol, and allantoic calcium and glucose), maternal parity (amniotic and allantoic CK, glucose, LDH, chloride) and newborn gender (allantoic phosphorus) was found. Further investigations are needed for addressing the origin of each fetal fluid biochemical composition in the dog and also to indeep possible differences in fetal fluids biochemical composition between normal and pathologic puppies, providing potential markers for the quick identification of newborns that need special surveillance and cares immediately after birth.

Cortisol fetal fluid concentrations in term pregnancy of small-sized purebred dogs and its preliminary relation to first 24 hours survival of newborns

Along the perinatal period, in mammals, cortisol (C) plays a pivotal role in the final intrauterine fetal maturation and in the early neonatal adaptation. Because of the scarce knowledge about canine perinatology, the present study was aimed to assess the C concentrations in amniotic and allantoic fluids collected, without invasiveness, from small-sized, purebred newborn puppies born by elective cesarean section, at term of pregnancy. Possible correlations between fetal fluid C concentrations and maternal parity, litter size, birth weight, Apgar score, were evaluated. In addition, the possible effect of fetal fluid C concentrations on newborn survival at 24 hours of age, and the effect of the litter or the newborn gender on fetal fluid C concentrations were also assessed. The results, obtained from 50 born alive, normal-weight puppies, without gross physical malformation, showed that C concentration was higher in allantoic than in amniotic fluid (P < 0.01), even if a strong positive correlation between the two fluids C concentration was found (P < 0.0001; R = 0.83). Neither amniotic nor allantoic C concentrations were correlated to maternal parity, litter size, birth weight, and Apgar score. Interestingly, higher amniotic (P < 0.05), but not allantoic, C concentrations were found in puppies not surviving at 24 hours after birth. Therefore, it could be suggested that this parameter may be useful for the recognition, at birth, of puppies needing special surveillance during the first day of age. A significant (P < 0.001) effect of the litter in both amniotic and allantoic C concentrations was found. In conclusion, the present results showed that in small-sized purebred puppies, born at term by elective cesarean section, the exact fetal, maternal, or placental source contributing to fetal fluid C concentrations remains to be clarified. From a clinical perspective, however, the evaluation of amniotic C concentration at birth seems useful for the detection of puppies that need special surveillance during the first 24 hours of age, and should be coupled to the early newborn evaluation by Apgar score. However, the small total number of newborns, and especially of the dead puppies enrolled in the present study, suggests that further, more-focused investigations on a large number of subjects are needed before the method could be considered for application in the clinical practices.

Transplacental transfer of Azithromycin and its use for eradicating intra-amniotic ureaplasma infection in a primate model

BACKGROUND

Our goals were to describe azithromycin (AZI) pharmacokinetics in maternal plasma (MP), fetal plasma (FP), and amniotic fluid (AF) following intra-amniotic infection (IAI) with Ureaplasma in pregnant rhesus monkeys and to explore concentration-response relationships.

METHODS

Following intra-amniotic inoculation of Ureaplasma parvum, rhesus monkeys received AZI (12.5 mg/kg every 12 hours intravenously for 10 days; n = 10). Intensive pharmacokinetic sampling of MP, FP, and AF was scheduled following the first (ie, single) dose and the last (ie, multiple) dose. Noncompartmental and pharmacokinetic modeling methods were used.

RESULTS

The AF area under the concentration-time curve at 12 hours was 0.22 µg×h/mL following a single dose and 6.3 µg×h/mL at day 10. MP and AF accumulation indices were 8.4 and 19, respectively. AZI AF half-life following the single dose and multiple dose were 156 and 129 hours, respectively. The median MP:FP ratio in concomitantly drawn samples was 3.2 (range, 1.3-9.6; n = 9). Eradication of U. parvum occurred at 6.6 days, with a 95% effective concentration (EC95) of 39 ng/mL for the maximum AZI AF concentration.

CONCLUSIONS

Our study demonstrates that a maternal multiple-dose AZI regimen is effective in eradicating U. parvum IAI by virtue of intra-amniotic accumulation and suggests that antenatal therapy has the potential to mitigate complications associated with U. parvum infection in pregnancy, such as preterm labor and fetal sequelae.

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

Insulin-like growth factor-I (IGF-I) and non-esterified fatty acids (NEFA) play an essential role in fetal growth and development. To date, fetal fluids IGF-I and NEFA levels at term canine pregnancy are unknown and could be related to the neonatal development and breed size. For these reasons, the aims of the present study were as follows: (1) to evaluate IGF-I and NEFA concentrations in fetal fluids collected from normally developed and viable newborn puppies born at term of normal pregnancies; (2) to assess possible differences between IGF-I and NEFA levels in amniotic compared with allantoic fluid; (3) to detect possible relationship between breed body size and IGF-I and NEFA amniotic and allantoic concentrations; (4) to evaluate possible differences in IGF-I fetal fluids levels between male and female puppies; and (5) to assess possible correlations between the two hormones in each type of fluid. The study enrolled 25 pure breed bitches submitted to elective Cesarean section at term because of the high risk of dystocia or previous troubles at parturition. At surgery, amniotic and allantoic fluids were collected and assayed for IGF-I and NEFA. IGF-I and NEFA amounts in both amniotic and allantoic fluids of different breed size bitches (small: ≤10 kg; medium: 11-25 kg; large: 26-40 kg) were detected, as well as the effect of gender on IGF-I levels. On a total of 73 amniotic and 76 allantoic samples collected by normal, viable, and mature newborns, the mean IGF-I concentration was significantly higher in amniotic than in allantoic fluid in all three groups, but the amniotic IGF-I levels were significantly lower in small and medium size bitches when compared with large ones. No significant differences were found in allantoic IGF-I concentrations among size groups. A significant effect of the puppy gender on IGF-I content in both fetal fluids was not reported. Regarding NEFA, in all the three groups, the mean NEFA concentration did not significantly differ between amnion and allantois, but in both fetal fluids, higher NEFA levels were detected in samples belonging to small breeds when compared with medium and large. These data strongly indicated that, also in the dog, a relation between fetal fluids IGF-I and NEFA concentrations and breed size exists. Further research is needed to elucidate the possible role of IGF-I and NEFA in the pathologic conditions related to canine fetal growth.