REPRODUCTION - Equine Pregnancy and Parturition Flashcards
What is maternal recognition of pregnancy?
Maternal recognition of pregnancy is the prevention of luteolysis to allow for continued progesterone production to maintain pregnany
How does maternal recognition of pregnancy occur in the mare?
In the mare, the movement of the embryo around the uterus triggers a currently unknown hormone which prevents secretion of prostaglandin F2α secretion
When does the embryo enter the uterus in the mare?
The embryo enters the uterus 6 days post ovulation
When does the embryo undergo fixation in the uterus?
The embryo will no longer be motile and undergo fixation at day 16 post ovulation
Where do embryos always fix in the mare?
Embryos always fix at the base of the uterine horn
What produces progesterone to maintain pregnancy in the mare?
The primary corpus luteum will produce progesterone. At 35-40 days gestation, the mare will produce additional follicles on the ovaries which will eventually transition to secondary corpus lutea and produce progesterone. Furthermore, at over 60 days of gestation, the placenta will also produce progesterone to maintain pregnancy in the mare
What are endometrial cups?
Endometrial cups are transient endocrine glands which invade the endometrium at around 35 - 40 days of gestation and produce equine chorionic gonadotrophin (eCG) until day 120 of gestation
What is the proposed function of equine chorionic gonadotrophin (eCG)?
Equine chorionic gonadotrophin (eCG) has LH-like activity and promotes the production of follicles and secondary corpus lutea allowing for elevated progesterone production to maintain the pregnancy between 35 to 120 days of gestation. Furthermore, eCG is involved in the maternal immunotolerance of foreign antigens produced by the foetus
(T/F) Endometrial cups can persist even after embryonic death or abortion
TRUE. Endometrial cups can persist to 120 days even after embryonic death or abortion and continue to produce equine chorionic gonadotrophin which can have effects on her oestrous cycle and make management challenging
What are the methods of pregnancy diagnosis in the mare?
Teasing
Vaginal speculum diagnosis
Oestrone sulphate
Progesterone
Equine chorionic gonadotrophin (eCG)
Transrectal ultrasound
Palpation
How can teasing be used for pregnancy diagnosis?
You can present the mare to a stallion when she would be due to come into oestrus again (16 - 20 days post ovulation) and see if she is receptive. If not, this can indicate she is pregnant
What are the limitations of teasing for pregnancy diagnosis?
Pregnant mares may exhibit oestrus behaviours resulting in a false negative
Presistent corpus luteum can result in a false positive
Early embryonic death can result in alteration of the oestrous cycle and a false positive
What is a sign of pregnancy on vaginal speculum examination?
Dry, pale, tightly closed cervix (however this is non-specific to pregnancy)
What is oestrone sulphate?
Oestrone sulphate is a hormone produced by the foetal gonads
When can oestrone sulphate be used for pregnancy diagnosis?
Oestrone sulphate can be used for pregnancy diagnosis over 60 days post ovulation, but labs recommend 90-100 days
What are the limitations of using serum progesterone levels for pregnancy diagnosis?
High serum progesterone levels are not specific to pregnancy and could be due to other factors (such as a persistent corpus luteum)
What are the limitations of equine chorionic gonadotrophin (eCG) levels for pregnancy diagnosis?
Endometrial cups can persist to 120 days even after embryonic death or abortion and continue to produce equine chorionic gonadotrophin resulting in false positives
What is the most commonly used method of pregnancy diagnosis in the mare?
Transrectal ultrasound
When can transrectal ultrasound be used for pregnancy diagnosis in the mare?
Transrectal ultrasound can be used 14-15 days post ovulation for pregnancy diagnosis in the mare
What can be detected on ultrasound at days 14 - 15 in pregnant mares?
Embryonic vesicle
What can be detected on ultrasound at days 25 - 30 in pregnant mares?
Foetal heart beat
What can be detected on ultrasound at days 45-50 days in pregnant mares?
Foetus (more obvious heartbeat and foetal movements)
What is the ultrasound schedule for pregnant mares?
14 days: Look for embryonic vesicle, count the corpus lutea and check for twins
16 days: Second twin check if necessary
28 days: Check for foetal heartbeat
45 - 65 days: Final check ± Foetal sexing
What can be an indicator to recheck a mare for twins on day 16?
If you count more than one corpus lutea during the first pregnancy check in the mare, this means more than one follicle has ovulated and there is an increased risk of twins
When can palpation be used for pregnancy diagnosis in the mare?
Rectal palpation can be used over 30 days post ovulation for pregnancy diagnosis in the mare
What is a sign of pregnancy on palpation in the mare at 14 -15 days?
Increased uterine tone and a long, tightly closed cervix (however this is non-specific)
What is a sign of pregnancy on palpation in the mare at 25-30 days?
Bulge on palpation of the uterus
Which horse breeds are at increased risk of multiple ovulations and twins?
Larger horse breeds are at increased risk of multiple ovulations and twins (particularly thoroughbreds)
What are unilateral twins?
Unilateral twins is when both embryos are fixed in the same uterine horn
What are bilateral twins?
Bilateral twins is where each embryo is fixed in a different uterine horn
What should you do if you detect a twin on transrectal ultrasound (day 14 - 15)?
If you detect a twin on transrectal ultrasound, you should ‘pinch’ it using your hand or the ultrasound probe
This is the preferred and most successful technique
Has to be done while they are mobile to prevent accidentally pinching both twins where they are fixed
How can you manage twins from 16 - 35 days gestation?
Prostaglandin (abort pregnancy)
Transvaginal ultrasound guided puncture and aspiration
McKinnon’s oscillation technique
What is the main risk of transvaginal ultrasound guided puncture and aspiration of the twin?
There is still a risk of puncturing both twins with the needle
What is McKinnon’s oscillation technique?
McKinnon’s oscillation technique is ultrasound guided grasping and oscillating (shaking) of the embryo until it detaches from the umbilical cord
How can you manage twins beyond 35 days of gestation?
Craniocervical dislocation
Surgery
Transcutaneous foetal injection
How long is gestation in the mare?
335 - 342 days
What can be used to indicate that the mare is readying for parturition?
‘Waxing up’ (occurs 1 - 72 hours before parturition)
Foal alarms
What is ‘waxing up’ in mares?
‘Waxing up’ is the dripping of colostrum in mares
How long does stage 1 of parturition last in the mare?
30 minutes to 4 hours
What occurs during stage 1 of parturition in the mare?
The mare will become restless and may even exhibit mild colic. Uterine contractions will begin and the foetus will be forced agaisnt the cervix, progressing cervical dilation until the chorioallantois will rupture and foetal fluid will escape (water breaks)
How long does stage 2 of parturition last in the mare?
Less than 30 minutes
What occurs during stage 2 of parturition in the mare?
There will be uterine contractions and strong, visible abdominal contractions and the foetus will be expelled
How long does stage 3 of parturition last in the mare?
Stage 3 should occur within 3 hours
What occurs during stage 3 of parturition in the mare?
Foetal membranes should be completely expelled (should occur within 3 hours post foaling)
When should the foal stand post foaling?
The foal should stand within 1 hour post foaling
When should the foal begin to suckle post foaling?
The foal should begin to sucke within 2 hours post foaling
What is a red bag delivery?
A red bag delivery is where there is premature seperation of the chorioallantois placenta from the endometrium prior to the birth of the foal, resulting in a rapid decrease in oxygen to the foetus and hypoxia
What is uterine involution?
Uterine involution is when the uterus returns to it’s normal state after pregnancy
How long should it take for the uterine involution in the mare?
It takes 7 days for the uterus to reduce in size, however it takes 14 days for histologic repair of the uterus
What can help to promote uterine involution in the mare?
Exercise can help to promote uterine involution in the mare
When would uterine torsion occur in the mare?
Uterine torsion usually occurs during the last trimester in mares, and rarely occurs during parturition
What are the clinical signs of uterine torsion in the mare?
Intermittent to acute colic
Tachycardia (sign of pain)
Depression (sign of pain)
Clinical signs depend on the degree of torsion
How do you diagnose a uterine torsion in the mare?
Rectal palpation
How do you treat a uterine torsion in the mare?
Rolling under general anaesthetic
Standing flank laparotomy
Ventral midline laparotomy
Vaginal correction
How do you roll the mare to correct a uterine torsion?
Determine if the torsion is clockwise or anticlockwise on rectal palpation. Put the mare under general anaesthesia and place her in lateral recumbency (right if clockwise torsion and left if anticlockwise torsion). Roll the mare opposite to the direction of the torsion and evaluate the position of the uterus using rectal palpation after every roll
What are the risks of rolling the mare under general anaesthesia?
Uterine rupture
Uterine artery rupture
Placental seperation
When can you do a vaginal correction to correct a uterine torsion in the mare?
You can only do a vaginal correction if the uterine torsion occured during parturition, as the cervix will be open, allowing you to correct the torsion vaginally
(T/F) You should always deliver the foal after correcting a uterine torsion
FALSE. Uterine torisions usually occur within the last trimester so it is best to leave the mare to deliver the foal naturally after correcting a uterine torsion
What are the two classifications of hydrops?
Hydroallantois
Hydroamnion
What is a hydroallantois?
Hydroallantois is an excessive, progressive accumulation of fluid within the allantois
What is a hydroamnion?
Hydroamnion is an excessive, progressive accumulation of fluid within the amnion
What are the clinical signs of hydrops in the mare?
Abdominal distension
Inappetence
Dyspnoea
Tachycardia
Rupture of abdominal musculature and/or pre-pubic tendon
Clinical signs associated with compression of structures (i.e. the diaphragm, stomach etc.)
How can you diagnose hydrops in the mare?
Rectal palpation
Abdominal ultrasound
How do you treat hydrops in the mare?
Treatment of hydrops in the mare depends if she is close to parturition. If she is close to term you can induce the pregnancy and assist with delivery whilst controlling the drainage of fluid, making sure to give IV fluids at the same time to maintain blood pressure. If the mare is not close to term, abort the pregnancy and assist with delivery in the same way as you would a live foetus
When do ventral abdominal wall hernias or prepubic tendon ruptures tend to occur in mares?
Ventral abdominal wall hernias or prepubic tendon suptures tend to occur in late gestation as the gravid uterus becomes very large and heavy
What are the clinical signs of ventral abdominal wall hernias or prepubic tendon ruptures?
Ventral oedema
Tachycardia
Tachypnoea
Difficultly moving
What is a key sign that the prepubic tendon has completely ruptured in the mare?
Udder will move cranially and the tuber ishium will be elevated
How can you diagnose ventral abdominal wall hernias or prepubic tendon ruptures in the mare?
Clinical signs
Abdominal ultrasound
How do you manage ventral abdominal wall hernias or prepubic tendon ruptures in the mare prior to parturition?
NSAIDs
Sling bandage
Restrict exercise
How do you manage ventral abdominal wall hernias or prepubic tendon ruptures in the mare at parturition?
Monitor very carefully for signs of preparing for parturition, i.e. foal alarms etc, and induce parturition when optimal. Inducing parturition allows for you to have lots of people there to assist in the parturition
What is the prognosis for ventral abdominal wall hernias or prepubic tendon ruptures in the mare?
This is a very high risk pregnancy as the mare requires strong abdominal contractions for stage 2 of parturition. Due to the damaged abdominal musculature, the mare will be unable to assist in this stage of parturition
(T/F) You can breed mares with ventral abdominal wall hernias or prepubic tendon ruptures subsequently
FALSE. You should not breed mare with ventral abdominal wall hernias or prepubic tendon ruptures
What are the obstetrical principles for managing dystocia?
Plenty of lubricant
Cleanliness
Protect the uterus and cervix
Have backup plans
What is the normal presentation of a foal at parturition?
Craniolongitudinal presentation
Dorsosacral posture
Extended head and limb position
What is the most common cause of dystocia in horses?
Dystocia in horses is typically due to abnormal posture of the foetus (i.e. legs, head back etc.)
Which factors should you assess when doing a clinical examination on a foaling mare?
Demeanour
Assess pain
TPR
You don’t have time for a full clinical examination
Which factors should you assess when you begin to vaginally examine a foaling mare?
Is the cervix open or closed?
What anatomy of the foal can you feel?
Is the foal alive or dead?
Can this foal be delivered vaginally?
What can you do to determine if the foal is dead or alive within the mare?
Movement
Pinch the hoof
Poke your hand in the mouth to test gag reflex
Heart beat/pulse
Always assume alive if unsure
What can be done to manage dystocia in foals?
Assisted vaginal delivery (AVD)
Controlled vaginal delivery (CVD)
Caesarean section
Foetotomy (if dead foal)
What is assisted vaginal delivery?
Assisted vaginal delivery is manual manipulation and gentle traction of the foal in a standing or recumbent, awake mare
What is controlled vaginal delivery?
Controlled vaginal delivery is where the mare is put under general anaesthesia, negating any uterine or abdominal contractions. You can use manual manipulation, gentle traction and can hoist up the mare’s hindquarters to help reposition the foetus
What is the maximum amount of time you should attempt to vaginally manipulate a dystocia before doing a caesarean?
30 minutes
What can you use for traction in foaling?
Foaling ropes and chains
Maximum traction equivalent to 2 persons to prevent damage to the foal
(T/F) You can use a calving jack for foaling
FALSE. You should never use a calving jack for foaling as foals are not as ameanable to extreme traction and there is a high risk of injuring the foal
What can be used to reduce uterine contractions in the mare?
Epidural
General anaesthesia
Sedation
Clenbuterol
(T/F) Never use oxytocin to aid dystocia in the mare
TRUE. Never use oxytocin to aid dystocia in the mare as dystocia in the mare is rarely caused by uterine inertia and is usually obstructive, and thus there is no indication for oxytocin and since oxytocin stimulates contractions, this can cause complications
What are retained foetal membranes in mares?
Retained foetal membranes in mares is where the placenta hasn’t been expelled within 3 hours post-foaling
Which horse breeds are at increased risk of retained foetal membranes?
Heavy breed horses
i.e. Friesians
What are the risk factors for retained foetal membranes in mares?
Prolonged gestation
Dystocia
Placentitis
Hydrops
Induced delivery
Caesarean section
Uterine inertia (rare in mares)
What is the pathogenesis of retained foetal membranes in the mare?
Retained foetal membranes in the mare will rapidly progress to metritis which can result in sepsis/endotoxaemia, laminitis and even death
How do you treat retained foetal membranes in the mare?
Oxytocin
Burns technique
Umbilical vessel water infusion
Uterine lavage
Broad spectrum antibiotics
NSAIDs
Exercise
Foal nursing
Why is oxytocin used to treat retained foetal membranes?
Oxytocin stimulates uterine contractions and can help to expel retained foetal membranes
How can you administer oxytocin to treat retained foetal membranes in the mare?
IM oxytocin every 4-6 hours or an oxytocin CRI
What is the Burns technique for retained foetal membranes?
The Burns technique is where you distent the chorioallantois with isotonic fluids using a tube, which may facilitate the release of the microcotelydons of the placenta from the endometrium and aid in the removal of the retained foetal membranes
This technique can only be used for intact foetal membranes
What is the umbilical vessel water infusion technique for retained foetal membranes?
You can take the umbilical cord and make a longitudinal incision into the vessel followed by advancing a stallion urinary catheter or foal stomach tube into the vessel. Hold the tube in place with you hand or cable ties and infuse water into the tube. The expansion of the vasculature can help to detach and expel the foetal membranes
What are the benefits of uterine lavage in managing retained foetal membranes?
Continue to lavage until the fluid runs clear
Stimulates uterine contractions
Removes infection and debris
Attracts neutrophils to the uterus (helps to fight infection)
When are antibiotics indicated for retained foetal membranes?
Broad spectrum antibiotics are indicated if the foetal membranes have been retained for beyond 6 hours
Why is exercise used in the treatment of retained foetal membranes?
Excercise releases endogenous oxytocin which will stimulate uterine contraction and help to expel the retained foetal membranes
Why is foal nursing used in the treatment of retained foetal membranes?
Foal nursing releases endogenous oxytocin which will stimulate uterine contraction and help to expel the retained foetal membranes
What are the clinical signs of metritis in mares?
Purulent, foul smelling vaginal discharge
Pyrexia
Anorexia
Reduced milk yield
Endotoxaemia/sepsis
Laminitis
Monitor the mare carefully and ice the hooves to try and prevent laminitis
What are the clinical signs of endotoxaemia/sepsis?
Profound depression
Tachycadia
Congested mucous membranes
Toxic lines
Brisk to prolonged CRT
Pyrexia to hypothermia
How do you treat metritis in mares?
Broad spectrum antibiotics
NSAIDs
Oxytocin
Uterine lavage
What are the clinical signs of uterine or ovarian artery rupture?
Sudden collapse and death
Tachycardia
Sweating
Trembling
Winnying
Restlessness
Colic
How can you diagnose uterine or ovarian artery rupture?
History
Clinical signs
Rectal palpation of haematoma of the broad ligament
Abdominal ultrasound
Abdominocentesis
What is the main aim of managing a uterine or ovarian artery rupture in the mare?
You wan’t to prevent a rise in blood pressure at this will worsen the haemorrhage and blood loss
How do you manage uterine or ovarian artery rupture?
Keep her calm
Keep foal with the mare if possible (to reduce stress)
NSAIDs
Sedation
IV fluid therapy
Blood transfusion
Naloxone
Aminocarproic acid
Why is naloxone used in the management of uterine or ovarian artery rupture in the mare?
Nalaxone is an opioid antagonist which may lower blood pressure
Why is aminocarproic acid used in the management of uterine or ovarian artery rupture in the mare?
Aminocarproic acid is an antifibrinolytic drug which will prevent fibrinolysis and breakdown of any blood clots
What are the risk factors for uterine prolapse in mares?
Dystocia
Abortion
Retained foetal membranes
How do you manage a uterine prolapse in a mare?
Why do you administer oxytocin after correcting a uterine prolaspe in the mare?
In the mare, you administer oxytocin after correcting a uterine prolapse as the underlying pathophysiology of a uterine prolase in the mare is that it becomes flaccid, atonic and relaxed which allows it to prolpase. Oxytocin triggers uterine contractions which should help prevent this from recurring
