Wk12 foetal to neonatal transition Flashcards
Which of the following occurs during the foetal to neonatal transition in the piglet? (piglets are different)
A. An immediate drop in blood glucose, followed by an increase due to endogenous glucose production
B. Decreased secretion of pulmonary surfactants to decrease lung resistance and promote respiration
C. Onset on non-shivering thermogenesis in brown adipose tissue results in no drop in body temperature
Colostrum intake over days 1-3 after birth transfers passive immunity to protect against infection
A - drop in blood glucose
- C = will get a drop in body temp initially, but also piglets do not have brown adipose, and also SHIVERING thermogenesis (only piglets) - B = increased secretion of pulmonary surfactants for lung resistance and respiration to occur D = colostrum intake is 1-3 hrs NOT days --> needs it before 24hrs otherwise fatal
Neonatal morbidity and mortality common causes:
- Dam (mother) issues
- Starvation due to mismothering (especially merino sheep)
- Mastitis = impact milk
- Poor BC
- Failed passive immunity transfer
- Stillbirth - disease and congenital abnormalities (infection, in utero infections, congenital malformation (breathing, suckling)
- Dystocia
- Predation
Thermoregulation
The more premature the neonate is, do we have more issues? Why?
- Yes, more issues, often related to failure in the major changes relating to heart (closures), lung maturation, limited thermoregulation (brown adipose tissue), incomplete renal development, exhaustion of glucose stored, failure of passive immunity transfer.
What are some of the major changes from foetal to neonatal transition?
- Cardiovascular changes: Closure of placental circuits, foramen ovale and ductus arteriosus (not needed as an adult)
- Pulmonary surfactant, respiration begins
- Endogenous glucose production
- Digestion + est of gut microbiome
- Reliance on passive transfer of immunity via colostrum
Increased renal function
Difference between precocial and altricial offspring
- Precocial = can get up and going pretty much right away = ewe, horse, cow etc
Altricial = dog, cat, require more care from parents for a pretty long time before they can get out on their own
Physiological changes around transition from foetal to neonatal transition: What overall drives these changes and what causes this surge?
- Foetal cortisol surge late in gestation
Caused by uterine crowding = foetus gets big enough and starts to get big stressed out = cortisol surge
Cardiovascular changes from foetal to neonatal: major changes in blood and BP are:
- Shutting off placental circuits –> separation of the placenta (breaking umbilical cord)
- Placenta = main gas exchange (acting like the lungs)
- Foetus:
- Mixed oxygenated and deoxygenated blood
- Low BP system
- Neonatal
- The oxygenated/deoxygenated blood is separated
High BP system, constriction of a. They don’t need anymore (umbilical a. = no bleeding)
- The oxygenated/deoxygenated blood is separated
2 structures that close in cardiovascular system from foetal to neonatal are
- Closure of:
- Foramen ovale
- Ductus arteriosus
Functional significance: setting up adult circulation, and creates separate blood flow.
Pulmonary (lung) and haematology changes from foetal to neonatal: major changes that occur in these are
- Pulmonary:
- Gas exchange switches from placenta to the lungs
○ Requires surfactants: cortisol (i.e. Surfactant production) and norepinephrine (surfactant release)
○ Require enough of this surfactant in their lungs in order for them to be breathe** –> important for premature birth/c-sections - Tactile stimuli, cooling and mild asphyxia promote respiration (first breathe)
- Gas exchange switches from placenta to the lungs
Haematology: foetal haemoglobin replaced by adult haemoglobin
Metabolism and thermogenesis changes: major changes in these
- Metabolism:
- Switch from continuous to intermittent energy supply
○ Will get a drop in blood glucose after birth (lost placenta supply)
○ Has to make glucose itself (glycogenolysis and gluconeogenesis)
○ Lipolysis
- Switch from continuous to intermittent energy supply
- Thermogenesis:
- Leaving controlled ambient environment - rectal temp drops sig post birth
Mostly occurs in non-shivering thermogenesis
- Leaving controlled ambient environment - rectal temp drops sig post birth
Major digestive changes from foetal to neonatal:
- Major change = switch from placenta to GIT nutrient intake
- Driven by foetal cortisol and first milk intake
- Increased tract motility
- Increased gastric enzymes
- Increased growth of villi and crypts
- Ruminants = take months for differentiation of stomach chambers
Microbiome = begins establishing immediately - key to neonatal and future digestive health
Renal changes: major change - what is it controlling?
- Kidney replaces placenta in regulating electrolyte homeostasis and waste secretion
Driven by increased BP: increased GFR, Na+ reabsorption, and urine osmolarity
Common causes of dystocia
- Large or multiple foetuses
- Foetal abnormalities
- Abnormal positioning
- Uterine fatigue or uterine torsion
Pretty common in dairy cattle
Immune system major change; when must colostrum be provided?
What can we do to support effective transfer?
- Transfer passive immunity via colostrum in first few hours is vital**
- Must happen in first couple of hours, otherwise survival chances significantly decrease
- Vaccinate the dam = more antibodies in the mother colostrum
Can bottle feed colostrum replacer if issues with mother/suckling
