• The most important change is an increase in divalent cations (Ca++, Mg++) in milk. 
• The increase in magnesium is more gradual and occurs earlier pre-partum than Ca++.  It is the increase in Ca++ that is most useful. 
• When calcium rises >10 mmol or 400 ppm, parturition is imminent.

Characteristics of parturition in mares  

• Stage 1 is characterized by restlessness, walking, frequent urination, sweating, the mare is anxious, looking at her abdomen, getting up and laying down, rolling. 
  • Most mares will rise at least once after going down, but repeatedly getting up and down may signal a problem. 
  • The foal has an active role in its final positioning, going from dorso-pubic to dorso-sacral. 
  • The duration of Stage 1 is usually about an hour or a little longer (10 min - 5.5 h). 
  • Stage 1 ends with the rupture of the chorio-allantois at the cervical star.  
• Stage 2 consists of 15 to 30 min of very forceful expulsive efforts. 
  • The foal is presented in the intact amnion, usually with one forelimb about 6 in. behind the other. 
  • The long umbilical cord remains intact until the mare rises. 
  • It was once thought that significant blood flow, up to 1 liter, occurred through the cord after birth and people were cautioned about breaking the cord too soon. 
  • However, more recent studies have shown that there is no significant blood flow in the cord after birth and there is no difference in the PCV between foals in which the cord is broken soon after birth and those in which the cord is left intact.  
• Stage 3 typically appears as a tranquilizing effect post-delivery. 
  • The placenta is usually passed in less than 3 h after parturition. 
  • After delivery, the navel should be disinfected with 2% chlorhexidine. 
  • Non-tamed iodine is associated with an increased incidence of patent urachus, and other problems because it is too harsh. 
  • Povidone iodine does not disinfect adequately.  
  • Good colostrum has a specific gravity >1.06 and adequate intake should be observed. Inspection of the placenta should be routine. 
  • Make sure that all the placenta has been passed. 
  • Check for signs of placentitis. Any abnormal areas may indicate septicemia of the foal. 
  • Treatment should begin immediately, before clinical signs appear in the foal. Also check for other abnormalities in the placenta. Areas of aplastic or hypoplastic villi are an indication of uterine pathology.  

Dystocia  

• Considerations to keep in mind in the management of dystocia are that the process of parturition is very rapid and very forceful. 
• The reproductive tract of the mare is easily traumatized. Mares can be unpredictable during dystocia and it is advisable to use caution.
  

Guidelines on when to intervene:  

• After 10 min of strenuous labor and no sign of the fetus perform an examination. 
• If the forefeet and muzzle are in the canal, allow the mare to continue. 
• After strenuous contractions for another 10 min, assist delivery. 
• The amnion, which is a white membrane, should protrude from the vulva within 5 min of rupture of the chorio-allantois. 
• If a red velvety membrane (the chorio-allantois) is seen at the vulva, a true emergency exists.  This is termed 'red bag'.
• Unfortunately, if intervention is needed, oftentimes the foal will be dead. 
• Assistance must be given rapidly if the foal is to be saved. 
• A weak or dead foal cannot assist in the process of parturition.

Proper restraint, both physical and chemical are important.  

• Minimize the use of drugs that will affect the CNS and cause respiratory depression of the foal. 
• For sedation or tranquilization, acepromazine is not recommended if the foal is alive because of its long clearance time. 
• Barbiturates are also not recommended because of severe fetal depression, even with doses that don't affect the mare. 
• Both xylazine and detomidine can be reversed with yohimbine (0.05 mg/lb, IV). 
  • Caution should be exercised if xylazine is used alone as it will sometimes result in hypersensitivity of the hindquarters. 
• Epidural anesthesia is not recommended because it takes too long to take effect, doesn't stop the abdominal press and may cause the mare to be unstable in the hindquarters if she ends up needing to be shipped somewhere or during recovery if she undergoes general anesthesia.  
• Short term field anesthesia can be accomplished with xylazine (1 mg/kg IV) or detomidine (10 µg/lb, IV) followed by ketamine (2 mg/kg IV) after the mare drops her head. Then administer "triple drip": 5% glycerol guaiacolate (GG) solution containing 0.5 mg/ml xylazine (or 20 µg/ml detomidine) plus 1 mg/ml ketamine administered at approximately 1.0 ml/lb/hr (if give a second bag use 0.25 mg/ml of xylazine).  
• If the foal is dead, you can use glycerol guaiacolate and thiobarbiturate.  
• For Caesarian section: give GG (5% Sol.) to effect, then ketamine (1mg/lb) then intubate (Isoflurane preferred over Halothane); if pre-medication is desired, 50 mg valium can be given IM, 10 mg butorphanol IV.  
• After delivery, give the foal Dopram (0.2 mg/kg, IV) and yohimbine if needed.
  
  

Cleanliness and lubrication are absolutely essential in the management of equine dystocia.

• Petroleum jelly is a good choice of lubricant. 
• Water soluble lubricants are acceptable but must be replenished more often. 
• Do not use a detergent as a lubricant because it has a de-fatting action on the tissues.
• Do not use J-lube, particularly if a C-section may be anticipated. J-lube has been found to be quite toxic if in the peritoneum.

Prompt assessment of the cause of dystocia is important as is relatively rapid decision making as to the course of action.

• Abnormal fetal posture is the most common cause of dystocia because of the long extremities and neck of the foal. 
• Normally, the foal is an active participant in parturition. 
• A weak or dead foal fails to participate in the process. 
• Congenital deformities such as wry neck, contracted tendons or ankylosis result in dystocia. 
• Dog sitting posture, foot-nape presentation (often causing a recto-vaginal laceration if not corrected) and nape presentation are fairly common problems. 
• Abnormal presentation, e.g. posterior or ventral-transverse also may be encountered. 
• Twins frequently result in dystocia. 
• Maternal causes, such as a tight vaginal-vestibular sphincter, a small vulva or Caslick's that was not opened may also be involved.
  
  

Premature separation of the chorio-allantois (or "red bag" in lay terms) is an obstetrical emergency. 

• This can be recognized by the appearance of a red, velvety membrane at the vulva before delivery of the foal. 

• The chorio-allantois must be ruptured immediately and delivery assisted because the foal will rapidly become hypoxic and anoxic. 
• Clients should be made aware of this condition because if they do not take action and await the arrival of a veterinarian, the foal will die of anoxia. 
• Premature placental separation is associated with placentitis (the placenta is too thick to rupture at the cervical star area), twinning, inappropriate induction methods (PGF) and unknown causes. 
• In many cases, the mare doesn't strain and the premature separation and failure to rupture interferes with delivery. 
• The foal progressively becomes hypoxic, weak, and dead. 
• This condition should be treated as an emergency with rupture of the membrane and delivery of the foal.
  

In any case, correction of dystocia should aim to minimize trauma to the mare.  

• Elevation of the hindquarters with the mare under general anesthesia provides additional room to manipulate the fetus. 
• Fetotomy is a viable solution, provided trained personnel and proper instruments are available. Otherwise, trauma to the mare is likely. 
• Caesarian section is an excellent alternative if facilities and personnel are available. 
• One of the biggest problems with fetotomy or caesarian section is the delay in making the decision to go forward with either option. 
• If the decision is delayed, the mare becomes exhausted and the reproductive tract traumatized. 
• The procedure and recovery then becomes more difficult. 
• The benefit of timely decision making is shown by studies examining elective c-section in mares in which live foals were delivered, some mares had repeat sections in following years, others had vaginal delivery and so forth.
  

• Induction of parturition in mares had a bad reputation for years because of inability to determine when the foal was mature enough for life outside the womb. 
• Induction of parturition based on gestation length alone or even with the additional information of udder development and relaxation of the ligaments and cervix resulted in the delivery of premature foals that needed intensive care to survive and frequently died in spite of the care. 
• With the knowledge of the changes in mammary secretion electrolytes, however, induction can now be performed safely. 
• The criteria to be met before induction include 
  • 330 d gestation minimum, 
  • colostrum in the udder, 
  • relaxation of the ligaments and cervix and most importantly, 
  • changes in the mammary secretions of >400 ppm (10 mmol) calcium. This is the KEY CRITERIA.
  • Inversion of the Na:K ratio is also critical (K should be > Na in mammary secretions)
    
    Methods of induction  
• It is advisable to place a jugular catheter before inducing parturition.

Oxytocin is the drug of choice.  

• The dose used is related to the intensity of parturition and the time to delivery. 
• The smoothest induction is with a low dose (5-10 IU bolus IV or 10 IU in 200 ml over 15 min). 
• The hypothesis is that a small dose begins the cascade and the endogenous response carries it on. 
• Other reported protocols include: single IM bolus (100 IU; 40-60 IU); multiple small IV injections (10-20 IU) every 10 min; IV boluses (20-40 IU) in 60 ml saline every 20 min; IV drip (60-80 IU) in 500 ml saline; but parturition is more rapid and forceful with these higher doses. 
• The trend is toward smaller doses which seem more physiologic.
  

PGF2a is effective in inducing parturition but results in an increase in premature placental separation, dystocia and foal mortality. It is NOT recommended

Indications are that if criteria for induction are met (including Ca level of mammary secretions), fluprostenol is safe and effective but the time interval from treatment to parturition is longer and more variable than oxytocin.

Steroids given repeatedly in high doses will shorten gestation length but are ineffective for inducing parturition for practical purposes.

• Retained placenta is rare due to the strong uterine contractions and microcotyledonary attachment of the placenta in mares. 
• Retention usually occurs in the non-gravid horn. 
• Unlike the cow, this should be treated as an emergency. 
• Tissue breakdown and bacterial growth may lead to metritis - laminitis - septicemia complex. 
• The placenta should be passed in 3 h, if not, initiate treatment prior to 4 -6 h postpartum. 
• The aims of treatment are to stimulate release of the placenta, evacuate the uterus, encourage involution, control bacterial growth and prevent laminitis.
   

• Treatment
  • Attempts to remove the placenta manually risk hemorrhage and trauma to the uterus. Manual removal is not recommended. 

• Prior to 4 - 6 h after parturition

• Re-distension of chorio-allantois may be attempted (Burn's technique)

• This method is usually quite effective if there is only a single hole in the placenta at the cervical star area. 
• Insert tube into placenta (not around it!) and distend with fluid (home made isotonic saline is good)
• Distend placenta (stand back when the fluid rushes out)
• Repeat until placenta releases

• Oxytocin therapy.

• The more effective oxytocin method is to administer the oxytocin in an IV drip (50 IU) in 500 ml saline over a 30 min period (this is the '5 method'...... 50 units, 500 mL, 0.5 hours)

• Other methods include a large IM bolus of 80-100 IU or small IV doses (10-20 IU) repeated every 15 min. 

• Always examine the placenta after passage to make sure it is all present. 
• It is helpful to know the normal appearance to be able to identify pathology.  

• After 4 - 6 h
  • Treatment should include broad spectrum systemic antibiotics, e.g. potassium penicillin (22,000 - 44,000 IU/kg, IV, QID) plus gentamicin (6.6 mg/kg, IV, SID) plus metronidazole (15 mg/kg, PO, BID). 

• In addition, uterine lavage with saline will reduce the accumulation of debris in the uterus. 
• The retention should be manually re-evaluated, at least daily. 

• Exercise is helpful, provided there are no signs of laminitis. 

• Make sure that tetanus vaccination is current. If not, administer tetanus toxoid. 

• Monitor the mare for signs of metritis - laminitis - septicemia complex.
  
  

Metritis - laminitis - septicemia complex.  

• This problem may develop due to gross contamination at foaling or retained placenta. 
• Affected mares exhibit depression, anorexia, congested mucous membranes, elevated temperature, pulse, and respiration rate. 
• Signs appear as early as 12 h postpartum. 
• Treatment consists of evacuating the uterus by large volume lavage (with saline) to eliminate debris and toxins. 
• Systemic therapy consists of systemic antibiotics, fluids, anti-inflammatories, tetanus toxoid, monitoring for laminitis, etc. as outlined previously for retained placenta.
  
  

Delayed uterine involution  

• Normally, involution in the mare is very fast. 
• By 7 d postpartum the uterus is 2 - 3 times the size of the uterus of a barren mare. 
• Mares with delayed uterine involution may have a discharge, occasionally exhibit dullness or mild pain and on rectal exam have a large, baggy, flaccid uterus. 
• Ultrasound exam reveals excessive fluid in the uterus. 
• Treatment consists of uterine lavage, oxytocin (50-100 U in 500 ml IV drip, or multiple small doses), exercise (provided there are no signs of laminitis), antibiotics, etc. Oxytocin therapy is especially important in cases where the foal is dead because then the normal endogenous release of oxytocin in response to suckling is absent.
  
  

Postpartum hemorrhage 

• Hemorrhage can occur into the broad ligament dissecting between the myometrium and serosa. 
• Clinical signs are characterized by a slow onset (12-48 h), with signs of colic, sweating, pale mucous membranes and elevated pulse. 
• There may be no signs but a hematoma is found on the prebreeding exam. 
• Diagnosis is by rectal exam and ultrasonography, aided by abdominocentesis. 
• Treatment is basically supportive care and consists of keeping the mare quiet and providing analgesics.
  
  

Uterine prolapse 

• This is a true emergency in the mare. 
• Even with rapid attention, the prognosis for survival is estimated as 50%. 
• The uterus should be cleaned and replaced as soon as possible. 
• The vulva is not sutured as in the cow. 
• Treat the mare for shock if needed. 
• Administer anti-inflammatories, systemic antibiotics, tetanus toxoid, oxytocin.
  
  

Uterine tears 

• The most common location is dorsal, just anterior to the cervix. 
• Initial treatment is for hemorrhagic shock. 
• Surgical repair is indicated, unless the tear is small and dorsally located. 
• They often lead to peritonitis. 
• Medical treatment consists of oxytocin (e.g. 20 IU every 2 h) and / or ergonovine 1-3 mg i.m., repeated every 2-4 h., along with antibiotics, and NSAID's. 
• Massage per rectum after surgical repair is indicated to prevent adhesion formation.
  
  

Recto-vestibular and perineal lacerations  

• These are more common in maiden mares due to a tight vaginal-vestibular sphincter. 
• They also occur in cases of fetal malpositioning, relative fetal oversize and overzealous assistance. 
• These will be covered more thoroughly in the surgery sessions. 
• Basically, immediate repair can be attempted but if not done immediately after occurrence, repair should be delayed until the initial inflammation has subsided.
  
  

Cervical laceration  

• Trauma to the cervix may interfere with its normal valve like action, affecting its competency to permit breeding and maintain pregnancy. 
• Damage is often iatrogenic following dystocia or fetotomy. 
• Treatment is surgical repair bur because the surgery is difficult and often unsuccessful, a BSE is recommended before surgery.
• Cervicitis / Vaginitis
• Necrotic vaginitis and/or cervicitis possible after dystocia

• Can be life threatening

• Can interfere with urination, defecation (swelling, abscess formation)
• Treat with antibiotics, NSAIDs, Tetanus toxoid  
   
• 

Gastrointestinal complications  

• Various complications can occur, including constipation, small colon bruising, and rupture of the rectum, cecum, or small colon. 
• Signs of colic and peritonitis follow. 
• The diagnosis can often be confirmed with paracentesis.

• Numerous indications exist, with twinning and inadvertent breeding being some of the most common. 
• The choice of method depends greatly on the stage of gestation. 
• Before 5-7 d post ovulation there is no effective method. The embryo has not entered the uterus yet and the CL is not responsive to PGF. 
• From 5 d post ovulation until the endometrial cups form at about 35 d, any number of methods will terminate pregnancy. 
  • Probably the simplest is an injection of PGF. 
  • Uterine lavage or manual crushing will also end the pregnancy. 
  • In the case of twins, where it is desired to maintain one vesicle while destroying the other, isolation of one vesicle and manual crushing is the preferred method.
    •  Because of the mobility of the early vesicles, isolation and crushing is best performed before d 16. 
• After the endometrial cups have formed, PGF can still be used to terminate pregnancy but multiple injections may be necessary.
  •  Uterine lavage or uterine infusion can also be used, as well as manual crushing if it is early enough to be able to grasp the vesicle. 
• Various methods have been employed to terminate one of a set of twins while allowing the other to continue to term. 
  • Currently one of the most promising is ultrasound guided aspiration. 
    • Although only about a third of mares treated with this technique will carry the remaining foal to term, this is a much higher percentage than would be successful if no intervention was practiced.
  • Fetal decapitation at about 75 days is the best method to terminate twins.

  • Twin Reduction by Cervical Dislocation (as told by Karen Wolfsdorf)

    • Best time to perform surgery is between 75 to 85 days

    •  Ultrasound to locate and identify fetuses, choose the one with the least surface area or closest to the tip of the horn

    • Give Banamine pre-op

    • Give 0.5 cc detomidine

    • Clip and give local block

    • Give another 0.5 cc detomidine

    • Give 1.0 cc propantheline (This is critical – if skip this, uterus will be too turgid to be able to perform task - available from HGD Pharmacy)

    • Grid incision (big enough to permit arm in abdomen)

    • Locate fetus, dislocate cervix by rolling between thumb and second finger (bigger fetuses – sort of like popping a cork on a bottle)

    • Routine closure

    • Post-Op Banamine q 12 h for 2 d

    • Double dose Regumate for 30 d

    • Pen/Gent for 3 d, then 7 more d of SMZ