Adaptation to Extrauterine life Flashcards
What affects neonates?
- Proper development
- Successful birth
- Successful adaptation
- Passive transfer
- Nutrition
What is a neonate age wise?
- Newborn within the first 30 days of lief
What are three elements that determine disease or not?
- Host
- Environment
- Agent
When in gestation do organs form?
- First months of gestation
When in gestation do organs develop?
- First half of gestation
When in gestation do organs grow and mature?
- Last trimester
What is the purpose of the fetal membranes fluids?
- Transfer oxygen and nutrients
- Eliminate waste
- Protect the fetus
- No immunoglobulin transfer
What type of placentation do ruminants have?
- Epitheliochorial
What types of stress happen during birth?
- Physical
- Temperature
- Light
- Sounds
- Oxygen deprivation
What are the two hormones that increase during stress/right after parturition?
- Epinephrine and cortisol
What can happen as a consequence of high epinephrine and cortisol in a sick neonate?
- They can mask conditions right after birth
When do crashes occur?
- Hours after birth often
How much time for respiratory system to be functional?
- Respiratory
How much time needed for immune system to be functional?
- Weeks to months
- It’s technically competent but naive
What are things that can vary in the neonate that will change how well it adapts to extrauterine life?
- Vigor
- Strength
- Stress of birth
- Maternal support
- Environment
What critical changes happen in the fetus as it transitions to neonate?
- Circulatory changes
- Pulmonary
- Acid-base
- Energy metabolism
- Temperature regulation
- Passive transfer
How does circulation change at birth?
- Pulmonary resistance increases, which closes the ductus arteriosus (Ductus arteriosus had been shunting blood from the pulmonary artery to the aorta)
- Foramen ovale connects the right and left atrium
- Ductus venosus bypasses the liver to go from portal circulation to the caudal vena cava
Describe the process of the lungs opening and closure of the ductus arteriosus in the neonate
- Umbilicus separates leading to anoxia
- Reflex gasping leaves the lungs aerated (most lung fluid is absorbed and surfactant keeps the lungs open)
- Decreased pulmonary vascular resistance (ductus arteriosus closes)
- Alveolar ventilation increases
- Ductus arteriosus closes in response to increased oxygen saturation ~5 minutes after birth
Describe closure of the foramen ovale in the neonate
- How quickly does it happen?
- Increased venous return to LA increases left atrial pressure and reverses the right to left shunt
- This occurs in about 10-20 minutes
What does relative prepartum hypoxia do to the ductus arteriosus?
- Dilation
Ductus venosus closure?
- Moot, nothing goes through it
- I guess it’s not that important
What happens to chest cavity at birth, and what is the significance?
- Chest cavity is compressed
- Lung fluids are partially expelled
- Recoil of chest leads to inspiration of air
- Diaphragm contractions further inflate the lungs
What causes initiation of breathing in the neonate?
- Loss of the immersion reflex, which inhibits breathing in the womb
- Breathing centers are stimulated (cold, light, touch, and limb movement)
- O2, Co2, and pH receptors are maximally stimulated
What can lead to respiratory distress? And what metabolic change will occur secondary to this?
- Early separation of placenta
- Prolonged labor
- Compression of umbilicus
- Maternal hyperventilation
- Cesearean section/malpresentation
- drugs (ideally under local)
- Immaturity
ALL of these lead to anaerobic metabolism –> lactic acid
How will the fetus present if there is in utero hypoxia?
- +/- hyperactive fetus!
- YOU NEED TO GET THEM OUT RIGHT AWAY
How can we help stimulate breathing in fetuses?
- Remove fetal membranes
- Clear airways fluids (suction)
- Stimulate (massage, move legs, nose, needle in the philtrum)
- Artifical respiration
- Remember lung capacity
- Nasal or endotracheal oxygen
- Keep sternal
What should you not do to stimulate breathing in fetuses?
- Spin through the air
- Swing
- Hang on fences
What does hypothermia indicate in neonates?
- Inappropriate adaptation
- All neonates lose body heat initially
- Heat production maximum 3 hours after birth
Environment factors that can impact thermoregulation
- Temperature
- Moisture
- Wind (the worst)
Species differences that can alter thermoregulation
- Body mass/surface area
- Brown fat (burn through it in 6-12 hours)
What is the critical temperature for a calf, and what does that mean?
55°F
- Temperature below which any animal has to increase caloric intake to maintain temperature
Other miscellaneous factors that can impact thermoregulation
- maternal behavior and energy/activity
How quickly is brown fat used to help with heat production?
1-5 days
What is the major form of heat production in neonates?
- Shivering!
- requires energy to continue (liver and other glycogen stores utilized within 4-6 hours)
- Colostrum and milk also
What should you check for on PE if you suspect hypothermia?
- Body temp (low)
- Suckle reflex (usually absent)
- Shivering (usually absent)
Causes of hypothermia in calves
- Environment (temp, wind, wetness)
- Low energy (hypoglycemia, agroceryosis)
- Disease (metabolic demands can tribute; if shocky they can’t absorb nutrition very well)
How to treat hypothermia?
- Dry the neonate
- Hot water bath
- Warm air
- Provide warm oral fluids
- Blankets, straw, etc.
For how long can the small intestine absorb large sized particles in the neonate?
- For the first 24 hours, the small intestine can absorb large sized particles
How long are neonates considered monogastrics?
- 2-4 weeks
What happens to metabolic demands in stressed, sick, or debilitated neonates?
- High metabolic demands
- Must provide adequate (extra) nutrition
When are the kidneys functionally mature?
- At birth
What is normal urine concentration in the neonate?
- Dilute urine from the milk diet
- Highly concentrated urine may indicate dehydration (rather than renal failure)
When does the nervous system mature?
- Rapidly near and after birth
What is the nervous system prone to?
- Trauma and asphyxia
What “abnormal” neuro exam findings are actually normal in the neonate?
- Lack menace
- Hypermetric
Skeletal system at birth
- Ossified at birth
How long can growth plates take to close?
- Several months to years
What can arise from trauma at birth?
- Metabolic and infectious problems
Rib trauma sequela
- Tracheal/esophageal problems later
Leg trauma sequela
- Unable to get up and nurse
When is immune system development complete?
- Mid-gestation
Is the immune system functional at birth?
- Yes, it’s just naive
Matures with time and exposure to antigens
What factors affect a successful birth?
- Health of the dam
- Size of the neonate and the dam
- Presentation and posture (head first, rear first)
- Assistance
Clinical findings that suggest dystocia
- Meconium staining
- Difficulty maintaining temperature (waxing and waning)
- Erratic blood glucose
- Nervous system problems
- Hypoxia - neonatal maladjustment AKA dummy
- Facial edema (nursing difficulty)
What do you have to worry about with a calf with dystocia?
- Increased risk of disease later in life due to metabolic and organ system derangements
When do you see disease conditions that were present during gestation or birth arise?
- First days of life
- Some are inapparent and hamper extra-uterine adaptation (e.g. sepsis, congenital defects, etc.)
Early signs of disease in neonates
- Does not stand and nurse within 2 hours
- disinterest in dam or by the dam
- Lack suckle
- Lacks curiosity
- Lacks vigor
- Often subtle and nonspecific
What is the veterinarian’s role with neonates?
- Realize that there can be subtle or no physical examination abnormalities
- May need diagnostic tests (CBC/Chem/BG/Blood cultures/FPT/US)
- Survival chances increase if treatments are initiated early and aggressively
- Wait and See approach is NOT ADVISABLE
What should we do if the owner suspects problems?
- Listen to them
- Monitor them carefully
- Keep warm and nourished
- Prep owners and provide instructions
- Call sooner rather than later
