Equine Parturition & Associated Problems

Equine Parturition & Associated Problems

1. 'High Risk Foaling' and 'High Risk' Neonates

   • ILO #1: Identify the factors responsible for production of a 'high risk foaling' and 'high risk' neonate Node in Red = Risk Factors 
   • Gestation Length
     • Horses: Gestation Length is Very Variable
       • Normal is 325 - 265 Days, Average = 335 Days (~11 Months) 
     • Premature (<320 Days)
       • Anything &lt;320 Days is premature. Premature more likely to have problems, need medical attention, and be less viable
     • Prolonged Pregnancy
       • Pregnancy maintained by Foal in Mare; Parturition stimulated by size of Foal, and it's production of signals (ACTH; Switch from Oestrogen to Cortisol)
       • If gone over 335 Days = Dysmature
         • As parturition is stimulated by Foal, if pregnancy goes on too long, probably means Foal is dysmature. Small, probably due to lack of placental supply.&nbsp;
     • Induced
       • As Parturition stimulated by Foal reaching correct size, and producing right signals, don't want to induce parturition in the Mare. Will result in Foal being born too early, before it was ready. Will be born small and weak.&nbsp;
       • Use Oxytocin to Induce
         • Use this to get Mare to pass Placenta too
         • Various Regimens; all low dose
         • If have to Induce, ideally do at Referral Centre
           • Have everything ready
             • Obstetrical and Resuscitation Equipment Appropriate Equipment
       • Only really Induce if major concern to Mare's health or Survival
         • E.g. Hydrops, Prepubic Tendon Rupture
       • Increases risk of complications with Parturition
         • Premature Placental Seperation
         • Dystocia
         • Retained Foetal Membranes / Metritis
         • Foal Morbidity / Mortality
   • Mare Factors
     • Previous Reproductive History
       • Has the Mare had any problems with Reproduction before, or produced any Abnormal Foals before? Increased chances she will again&nbsp;
     • Poor Perineal / Pelvic Conformation
     • Poor Mare Health
       • Uterine / Vaginal Rupture
     • Poor Nutritional Condition
       • Both this and poor Mare Health will lead to poor Colostrum
     • When was Mare last scanned after covering?
       • Want to know if she has been scanned. Scanning will tell us if she is still pregnant, help identify stage of pregnancy and if any major problems. Also help us identify twins.&nbsp;
     • Placentitis
       • Did Placenta look okay after this foaling?
     • Twins
       • Twins generally bad news. Very small chance will carry both to full term. Usually both will Abort, or one will be born healthy, and the other very small and sick, or one born, other aborted.&nbsp;
   • Placental Dysfunction
     • Infectious
       • Placentitis
         • Automatically 'High Risk Foal', as chance of being born with infection
         • Foal coming from Mare with Placentitis automatically 'High Risk'
           • High Risk of Septicaemia for Foal
     • Non-Infectious
   • Other Complications
     • Hydrops amnion/allantois
     • Prepubic Tendon Rupture
     • Ventral Abdominal Hernia
       • DD = Oedema

2. Abortion

   • ILO #2: Describe the aetiologies, methods of investigation, control and prevention of abortion in the Mare.
   • Causes
     • Placental Dysfunction
       • Will often see premature Udder Development and Lactation by the Mare if she is having Placental Dysfunction.&nbsp; Due to increased ACTH production by stressed Foetus. &nbsp;
       • Infectious
         • Placentitis
           • Usually picked up as an Ascending Infection, if Cervix is not properly closed. Occasionally can be Haematogenous, and can also be Venereal (acquired at covering).&nbsp; Infect Placenta at Cervical Star. Cause thickening and loss of function of Placenta. &nbsp;
           • Signs & Diagnosis
             • SIgns
               • Purrulent Vulval Discharge
                 • If look with Speculum, will see Discharge is coming from Cervix
               • Month 7-8
                 • Signs often seen at months 7-8 of Pregnancy
               • Premature Udder Development and Lactation
                 • Due to Foetal stress, and increased Foetal ACTH
             • DIagnosis
               • Ultrasound
                 • Look for thickening of Placenta, and may see areas of seperation from Uterus as well
               • Culture
                 • Take sample of Allantoic Fluid, culture to see what Bugs are there causing the problem.&nbsp; Helpful for deciding what ABs to use. &nbsp;
           • Treatment
             • Near Impossible to Eradicate Infection
               • Overall, relatively Guarded Prognosis.&nbsp; Aim of treatment is to minimise infection, and give Mare best chance of reaching full Term&nbsp;
               • Long-term Antibiotics
                 • Going to put on ABs as soon as Diagnosed, and keep on them until Term
               • NSAIDs
                 • To prevent Pyrexia
               • Tocolytics
                 • Used to prevent Contractions, in order to help prevent Premature Parturition
           • Risk Factors
             • Mostly related to Mare's Conformation. 1. Poor Perineal Conformation = increased risk of Faecal Contamination of Vestibule 2. Breed (Thoroughbreds) 3. Poor BCS 4. Increased risk with Parity (number of previous births)&nbsp;
           • Usually Bacteria, occ. Fungii
             • Pre-mate testing
               • Most Mares these days tested for Pseudomonas, Klebsiella and&nbsp;Taylorella equigenitalis&nbsp;before being covered.&nbsp; These bugs cause Contagious Equine Metritis (CEM). Also cause Infertility, Placentitis and Abortion&nbsp;
             • Most Common = Streptococcus
             • E. Coli, Pseudomonas
       • Non-Infectious
         • Twinning
           • Twins have to share Placenta, often means both don't get adequate nutrition
         • Toxic
           • Fescue Toxicity is most common. Seen more in N. America.&nbsp;
         • Premature Placental Separation
           • Owner may see this as a bit of bloody discharge. Would investigate by looking at Cervix with Speculum. Confirmed if see bleeding through Cervix into Vaginal Vestibule.&nbsp;
       • Most Common Cause of Problems
         • Placental Dysfunction is the most common cause of a Mare having an Abortion, or Still-Birth, or producing a weak foal.&nbsp;
     • Infectious
       • Leptospirosis
       • Equine Herpes Virus
         • Highly Infectious! Aborted materials will be packed with Virus
       • Equine Viral Arteritis
       • High Risk of Neonatal Sepsis if Foal survives
     • Non-Infectious
       • Dodgy Foal
         • E.g. Twins, Chromosomal Abnormality
       • Dodgy Placenta
         • E.g. Dysfunction, Umbilical DIsorders
       • Dodgy Mare
         • E.g. Nutrition
         • Hydrops (Very rare)
           • Excessive accumulation of either Allantoic or Amniotic Fluid in the Uterus.&nbsp; Better prognosis if caught early on. Fairly poor if late on. Referral. Particularly seen in last trimester. &nbsp;
     • Toxic
       • Fescue
         • Particular to North America
   • Investigation
     • Monitoring Foetal Well-being
       • As well as using these 4 nodes, textbooks say can look at Foetal ECG and other Hormones, but in practice rarely done.&nbsp;
       • Mare History
         • Has she had Reproductive problems before? Need to be aware of these.&nbsp;
       • Rectal Exam
       • Ultrasound
         • Can look at both Foetus and Placenta.&nbsp; Trans-Rectal or Transabdominal approach&nbsp;
       • Vaginal Exam
         • Look down Vagina with a Speculum. Can examine the Cervix.&nbsp;
     • Tissue Sampling
       • All potentially very infectious!
         • Treat as if EHV until proven otherwise.&nbsp;
       • Foetus
         • Can potentially send whole thing. Most important things are Lung and Liver, as these will have Viral Occlusion Bodies if there is EHV
       • Mare
         • Paired Serum Samples of Uterine Swab
       • Placenta
         • Whole thing fresh, or samples fresh or in formalin
   • Uncommon after Day 120
     • Complications are uncommon after Day 120.&nbsp; When they do occur though, can have implications for Survival of both Foal and Mare, and if Mare survives, may affect future Fertility. &nbsp;

3. Parturition

   • ILO #14: Demonstrate an understanding of normal and abnormal parturition to make decisions regarding the appropriate diagnostic, therapeutic and surgical interventions in suspected or actual cases of Dystocia.
   • Normal
     • 3 Stages
       • Stage 1: Preparation for Foetal Expulsion
         • Foetus getting into Position; Mare appears 'Colicy'
           • Mare can be Restless, Sweating, Flehmen's Reaction, Mild Colic. &nbsp; Foetus moves so hopefully head and forelegs form 'wedge' at Cervix
         • 1-4 hrs, up to 24hrs
           • Ends with Chorioallantoic Rupture
       • Stage 2: Expulsion of Foal
         • By Uterine and Abdominal Contraction Usually lying down. Usually happens at night, when not being watched&nbsp;
         • <20 mins
           • Ends with Expulsion of Foal
             • Don't want Mare to get up and run off
               • If gets up and runs off prematurely, be left with a weak, hypovolaemic foal.&nbsp;
               • Blood Supply and Umbilical Cord
                 • Important that Umbilical Cord is still attached at this point. Still a large volume of blood flowing.&nbsp; Foal will receive nearly a third of its total blood supply after it has hit the deck. &nbsp;&nbsp;
         • 'Red Bag' Delivery
           • Will see Chorioallantois coming out with Foal. Should be White &amp; Translucent.&nbsp; If red and opague, means Placenta has detached early, and is coming with the Foal. Foal is at risk of asphixiation, need to tear bag and pull ourselves. &nbsp;
         • Need hole in Chorioallantoic Sac
           • So Foal can breathe.&nbsp; Normally hole be created by Foal's feet, or Mare will nibble.&nbsp; Ensure amnion ruptures, and not occluding nose or mouth&nbsp;
       • Stage 3: Expulsion of Foetal Membranes
         • More Uterine Contractions: Expulsion of Foetal Membranes
           • Again, may seem a bit Colicy
           • <3hrs
         • Examine Membranes after for Abnormalities
           • Look at entire Placenta (if possible). Turn inside out to look at Endometrial Surface. Look for any thickening, sings of infection, Placentitis. WIll give us heads up if foal is 'High Risk'
         • Umbilical Cord: <1m, not Twisted
           • Cords &gt;1m prone to Twisting.&nbsp; Twisting leads to poor oxygen delivery to foal, leads to Perinatal Asphyxia Syndrome&nbsp;
   • Abnormal
     • Uterine Torsion
     • Dystocia
       • Thankfully uncommon (1-10%; higher in Miniature Breeds and Clydesdales)
       • 'True Emergency'
         • 'Requires Timely and Skilled Intervention'
         • Discuss options with Owner ahead of time
           • What Owner chooses will depend on chance of survival of Mare and Foal, and the future use of both. If willing to do Caesarean Section, probably want to send to Referral as soon as realise is Dystocia. &nbsp;
         • Heavy Sedation +/- Rapid Epidural
           • Epidural between C1 & C2
             • Aiming to go between 1st and 2nd Coccygeal Vertebrae Numbs Perineum, Vulva, but doesn't compromise ability to stand. Find by cranking Tail up and down, feel a depression. &nbsp;
             • Mepivacaine +/- Alpha-2 Agonist
               • Note: Takes a long time to work (about 20 minutes), and won't completely stop the contractions
           • Poss have to do GA
             • If Epidural doesn't stop Uterine contractions
             • If still can't pull out - Caesarian Section
       • Very Strong Contractions
         • Difficult to correct Malpresentations
         • Risk of Rectovaginal Fistulation
   • Prediction of D.O.B.
     • Gestation Length
       • Limited Use as so Variable
     • Mammary Development
       • Udder Enlarges 2-6 weeks B.T.
         • B.T. = Before Term Maiden Mares will lag behind in Udder development. Some may still have relatively small Udders even after giving birth. Milk Production will stretch the tissues and enlargen the Udders.
       • Waxing Up 24 - 48 hourse B.T.
         • Sticky, waxy secretion pushed out of Teats 1-2 days before Term.
       • Some Drip Milk hours before
         • Some may drip milk hourse before. Need to check with owner hasn't actually run milk, in case has lost Colostrum.
         • Mammary Gland Secretions
           • Can be used 24-48 hours before
           • Various Stall Side Kits available
             • Mostly look at changes in Electrolyte balances. Usually Ca2+, Na+, K+. Foaling usually within 12 hours of Ca2+ being more than K+. &nbsp;Fluid also goes from Clear to Milky White, due to increased Ca2+.&nbsp;
     • Physical Changes
       • Relaxation of Sacrosciatic Ligaments
         • Will see Gluteal Muscles dip. This occurs gradually over the last few weeks of pregnancy.
       • Cervical Softening
         • Begins to soften ~1 month before Term. Most obvious during Stage 1 of Parturition. Obviously an Internal thing&nbsp;
       • Relaxation of Vulva
         • Occurs much closer to Term, just a few hours before. Is much less obvious in Maiden Mares. Maiden Mares sometimes need their Vulva to be surgically cut and opened wider &nbsp;(An Episiotomy)
       • Drop in Body Temp (1oF in last 12 hours)
         • Can be useful to ask owners to measure Body Temp. Will drop by 1 degree Fahrenheit 12 hours before term.
     • Monitoring Devices
       • Much more common these days.&nbsp;
       • CCTV / Webcams
         • Most folk will use these now
       • Actual 'Monitoring' Devices
         • Best of these = Foalert.&nbsp; Activated by Vulval Seperation. Problem if Dystocia doesn't cause Vulval Seperation &nbsp;
   • Foals more fragile; Smaller Time Frame
     • Have a much narrower time frame than would in Sheep or Cattle. (Can die after ~20mins) Foals less able to tolerate insult pre &amp; post partum&nbsp;

4. Retained Foetal Membranes

   • 2-10% of Mares Usually Non-Gravid Horn&nbsp;
   • (Post Partum Haemorrhage)
     • Not covered in ILOs
   • Want out within 6 hours
     • Much quicker than in Cattle or Sheep
     • Septic Metritis, Laminitis, Tetanus
       • Problems can get if doesn't come out quick enough
   • Risk Factors
     • Twins
     • Dystocia
     • Caesarian
     • Abortion
     • Uterine Inertia (due to Hypocalcaemia)
   • Treatment
     • Check over next few days, in case develops Metritis, Laminitis, or Tetanus
     • Burn's Technique
       • Fill Chorioallantois with Fluid, and distend the Uterus. Causes Placental Membranes to come away, and Uterus to contract again.&nbsp; Know when put enough in as she starts pushing it back out at you. Can help with gentle pressure.&nbsp;
       • Never pull excessively; Can tear Uterus
     • Oxytocin
       • Different regimes; frequent low dose
     • ABs, NSAIDs, Tetanus Toxoid +/- Antitoxin

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