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

Vet Med Sci. 2024 May;10(3):e1452. doi: 10.1002/vms3.1452.


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.

Keywords: allantoic; amniotic; cat; dog; fetus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allantois / metabolism
  • Amniotic Fluid* / chemistry
  • Amniotic Fluid* / metabolism
  • Animals
  • Cats / physiology
  • Dogs / physiology
  • Female
  • Gestational Age
  • Hydrocortisone / analysis
  • Male
  • Pregnancy
  • Pregnancy, Animal / metabolism
  • Pregnancy, Animal / physiology


  • Hydrocortisone