Equine Dystocia and Abortion

Equine Dystocia is

A medical emergency

Equine dystocia incidence is

1-10%

What are the causes of equine dystocia?

abnormal presentation, position, most commonly posture

Potentially caused by hydrocephalus (esp in pony breeds)

What are your different factors to consider in dystocia cases?

Mare survival, fetal survival, mare’s future fertility

Why do we define dystocia occurring?

Stage 2 of labor lasts more than 30min

When managing equine dystocia, what should we do on site?

Brief physical exam, manual palpation of fetus within mare, assess fetal live-dead status

Rule out ‘dystocia’ when it is actually a different condition

What differentials may present similar to a dystocia?

Colic, uterine torsion, ruptured uterine artery, impending abortion, hydrops

What is the ideal presentation of a fetus during parturition?

Cranio-longitudinal

What is the ideal position of a fetus during parturition?

Dorso-sacral

What is the ideal posture of a fetus during parturition?

Extended head and limbs

What is repulsion when managing dystocia?

Pushing the fetus back from the pelvic canal into the uterine cavity to gain space for correction of abnormalities

What is rotation when managing dystocia?

Manipulation of the fetus on its longitudinal axis to bring it to the normal dorsosacral position

What is version when managing dystocia?

Difficult and very uncommon. Requires manipulation of fetus from transverse presentation to normal longitudinal

Treatment of dystocia: What can be done farmside?

Mutation/manipulation of fetus, maybe requiring repulsion. Limited time frame to attempt.

Use traction to aid (no mechanical assistance) is helpful

Consider fetotomy if foal is dead

Treatment of dystocia: What can be done after rapid referral?

Mutation/traction under GA, C-section

How long do you have to attempt mutation/repulsion of the foal farmside?

10-15min

What delivery option is available to us that can be performed when the mare is awake, standing or recumbent?

Assisted vaginal delivery (AVD)

What delivery option is available to us that must be performed when the mare is under GA, no uterine/abdominal contractions present, and mare hindquarters can be hoisted to reposition fetus?

Controlled vaginal delivery

Other than Assisted vaginal delivery and controlled vaginal delivery, what options do we have for dystocia management?

Cesarean section surgery or Fetotomy

What are obstetrical principles to keep in mind?

‘20min rule’

Use plenty of lubricant maintain cleanliness, protect uterus and cervix

Be prepared for a continuum of potentially changing strategies

What is the most common problem resulting in dystocia with the mare?

Abnormal posture

When using traction to aid parturition, what equipment/personnel is recommended?

OB chains or foaling ropes + 2 persons to apply traction

How should you use traction to aid parturition?

Work with mare, pull with contractions, relax between

Wal shoulders through the pelvis

For the mare, do we want to increase or decrease uterine contractions when facing dystocia?

Decrease

What uterine relaxants can we use in the mare?

clenbuterol or buscopan (tocolytic drug)

What sedation can we use to help with restraint in the mare?

Alpha2 and butorphanol

What should we not give to mares to aid in dystocia?

Oxytocin

When do we refer for dystocia cases?

<60 min after chorioallantoic rupture (include time of transport)

What is the most important factor indicating foal survival after a dystocia event?

Highly dependent on early recognition, duration/type, intervention

What is the survival rate of the mare after a dystocia event?

Moderate to high

What is the mare future reproduction capabilities after a dystocia event?

Good in absence of uterine/cervical trauma

What are features of retained fetal membranes?

>3 hours post-partum. Incidence 2-10% in light breeds (30-54% in Frisians and heavy breeds)

EMERGENCY

What are risk factors predisposing a mare to retain the fetal membranes?

Dystocia, prolonged gestation, placentitis, uterine hernia, C-section, fetotomy, hydropsy, induced delivery

What is the typical time frame to expel fetal membranes?

30min - 3 hours

What are the survival rates when treating for a retained fetal membrane?

Prompt = generally OK

Retained fetal membranes leads to rapid development of

metritis

In regards to fetal membranes, one small piece is

just as bad as the whole placenta

What are sequela to metritis?

Septicemia/endotoxemia, laminitis, death

What are signs of Retained fetal membranes → metritis → speticemia?

Fever, vaginal discharge, endotoxemia, depressions, toxic mucus membranes

If post partum we suspect metritis, what should be done for the mare to monitor at a minimum?

TPR 2-3 times/day, Digital pulses, CBC

What should we do for the mare to ‘get ahead’ of potential laminitis?

Frog support, ice feet, ± radiographs if suspicious

What can we use to treat retained fetal membranes 4-6 hours post foaling?

Oxytocin q4-6h, Ca gluconate, consider manual removal (controversial, can cause damage, can lead to prolapse

What is the burns technique when trying to treat retained fetal membranes?

Used for expelling intact membranes. Distend with isotonic fluid for 10-15 min.

Only perform 4-6 hours post foaling

What can we do to treat retained fetal membranes if it has been >6-12 hours post foaling?

Broad spectrum antibiotics (procaine penicillin + gentamicin ± metronidazole)

NSAIDS, exercise and encourage nursing

What can be considered when fetal membranes are retained, but we have access to the umbilical vessel?

Tube <9mm diameter pas into vessel. Connect other end to water hose with flow valve. Work with mare and can pass membranes within 10 min if successful

What are features of uterine lavage?

Used to stimulate uterine contractions, physically removes bacteria and cell debris. Attract neutrophils to uterus

Repeat until fluids run clear

Can use LRS, isotonic saline, or 90g NaCl in 10L of tap water

How can we treat metritis post-partum?

Broad spectrum antibiotics, NSAIDS (flunixin), Oxytocin (IM QID), consider uterine lavage

What are features of post-partum metritis in the mare?

Low incidence, increased with traumatic foaling ± retained fetal membranes

<10 days post-foaling

What is the etiology of metritis post-partum?

Uterine atony, disrupted endometrium, idiopathic

What clinical signs would be seen in metritis?

Anorexia, depression, fever, elevated HR and RR, lameness, decreased milk production, dehydration, fetid vulvar discharge (general unwell signs)

What are features of uterine or ovarian vessel rupture post-partum?

Usually occurs at parturition, occasionally pre-partum. May be fatal

diagnosis is difficult

What are clinical signs of uterine or ovarian vessel rupture?

Sweating, trembling, whinnying, tachycardia (60-140bpm)

How can we diagnose a uterine or ovarian vessel rupture?

Postpartum mare, palpation (if possible can find a hematoma in broad ligament), transabdominal U/S, abdominocentesis

What is the treatment for uterine or ovarian vessel rupture?

Keep mare quiet and comfortable, no excitement.

Keep foal with mare unless grave danger, use NSAIDs

AVOID RISE in BP!

How can we control BP of mare when recovering from a uterine or ovarian vessel rupture?

Sedation, fluid therapy, blood transfusion, naloxone, aminocarpoic acid, Yunnan Baiyo

What are potential causes of uterine prolapse?

Dystocia, RFM, abortion

What is the etiology of uterine prolapse?

Flaccid, atonic, relaxed uterus

What is the treatment for a uterine prolapse in the mare?

Keep uterus over pelvic brim, clean with water.

Manual replacement, manual replacement

Anesthetize and hoist the mare. Pain management (xylazine/butorphanol)

Administer oxytocin once in place, administer broad spectrum antibiotics for obvious reasons

Why may we be unable to determine diagnosis of abortive causes in the mare?

Poor quality of aborted material, incomplete aborted material, no diagnostic lesions identified

What is the minimum aim to rule out when performing an abortion investigation?

Infective fetal conditions, placental infections, umbilical cord problems, twinning, severe developmental disease

What are features of twin pregnancies?

Unsustainable, placental insufficiencies

Death in one or both fetuses (± abortion)

Rarely carried to term

What is fetal mummification?

Fetal death in-utero without bacterial contamination (typically caused by twins)

What is fetal maceration?

Fetal death in-utero and bacterial contamination present

What signs may the mare show when fetal maceration ahs occured?

Brown vulvar discharge, not systemically ill

What are causes of fetal maceration?

Cervical abnormalities, ascending placentitis

How can we diagnose fetal maceration?

Palpation, Ultrasound, hysteroscopy, uterine lavage, endometrial biopsy and culture

What is the treatment for fetal maceration?

Manual removal (PGF, cervix - PGE gel)

What causes 10-15% of all equine abortions?

Equine Herpes virus

What can Equine Herpes Virus - 1 cause?

Respiratory disease, myeloencephalopathy, fetal neonatal pneumonitis, abortion

What can Equine Herpes Virus - 4 cause?

Abortion

What are features of Equine Herpes virus?

Horse is natural host, natural immunity short lived (4-6 months)

Latent carriers (reactivation of virus)

How is Equine Herpes virus transmissible?

Aerosol route, direct or indirect contact of nasal mucosa, aborted fetuses, transplacental

What is the pathogenesis for equine herpes virus?

Vasculitis (placental thrombosis) and cotyledonary infarction

What are clinical signs of EHV?

Abortion >5 months

Fresh foal: 4-14 weeks psot infection, no premonitory signs

Infected foal: borna live - fatal viral pneumonitis

How can we diagnose EHV?

Gross examination and histopathology of fetal tissues (intranuclear inclusion bodies)

Viral isolation or PCR (fresh liver and lung tissues)

Virus neutralizing antibodies (fetal blood)

How can we control EHV?

Separate pregnant mares from young stock, quarantine new mares, isolate mares who abort

Good hygiene - abortion material, membranes, and fluid

Vaccinate mare at 5, 7, and 9 months of pregnancy

What are features of equine viral arteritis?

Highest prevalence in standardbreds and warmbloods

What is the transmission of equine viral arteritis?

Respiratory secretions, venereal, transplacental, carrier state (stallion)

What are clinical signs of equine viral arteritis?

Majority: asymptomatic

Fever, anorexia, dependent edema, periorbital edema, conjunctivitis

Abortion at 3-10 months (10-70%)

How can we diagnose equine viral arteritis?

Viral isolation (aborted fetus, nasal discharge from mare, semen from stallion)

Paired serology titers (confirm exposure of mare, indirectly identify carrier stallion)

Flase positive after vaccination

Natural infection stimulates strong lasting immunity

How do we control EVA?

Do not breed carrier stallions, if negative mare to positive stallion vac 3 weeks prior, if negative mare to negative stallion serology test prior to breeding

In an outbreak: Test, isolate, disinfect

Features of Mare Reproductive Loss syndrome

Early fetal loss, late term abortions, weak foals

Etiology: Eastern tent caterpillar

USA abortion storm in 2001 and 2002

What are features of late term abortions caused by Mare Reproductive Loss syndrome?

Asymptomatic, Stage 2 and Stage 3 occur together. Explosive

Red bag common, dystocia

Funisitis and amnionitis (from streptococcus and actinobacillus)

What are characteristics of weak foals as a result of Mare Reproductive Loss Syndrome?

Asphyxia, systemic inflammation, edematous placenta

What are characteristics of mares suffering illness as a result of Mare Reproductive Loss Syndrome?

Fever, Azotemia, colic, anorexia, pericarditis

How can we diagnose MRLS?

Early fetal loss, late term abortion, pericarditis in mares, horses grazing close to black walnut trees/caterpillar nests

How can we prevent MRLS?

Tent caterpillar control (pyrethroid insecticides)

What are features of Equine amnionitis and fetal loss?

Austrailia, first described in 2004, causes abortion and stillbirths 1-4 months after initial exposure

April-September Can lead to birth of compromised live foal

What are clinical signs of Equine amnionitis and fetal loss?

Allergic reaction (skin wheals. facial swelling), amniotic fluid echogenicity, vascualr engorgement of amniotic vessels, funisitis

How can we diagnose Equine amnionitis and fetal loss?

Caterpillar presence and histopathology

What are features of umbilical cord torsion?

Length in TB foal should be <80cm

Normal to see 4-5 gentle twists

When would we diagnose umbilical cord torsion?

>12 twists ± vascular constriction

What is the incidence of palcentitis?

3-7%

What is the most common type of placentitis seen in mares?

Ascending

What are other, less common types of placentitis?

Hematogenous, nocardioform

What is the etiology of placentitis?

Pathogenic organisms pass through cervix, esp Streptococcus, E. coli, Klebsiella, pseudomonas, aspergillus, candida

Less common: Leptospira, nocardia, actinomycetes

What are clinical signs of placentitis?

Premature udder development, vulvar discharge, asymptomatic

How can we diagnose placentitis?

Normal CBC and fibrinogen, SAA elevated?, Elevated progestogens, decreased estrogens

Collect samples from vaginal or cervical discharge (C&S)

Transrectal US: Looking to measure Combined thickness of uterus and placenta, assesses edema of allantochorion, find placental separation

Combined thickness of uterus and placenta of <5mm indicates what gestational age?

<270 d

Combined thickness of uterus and placenta of <8mm indicates what gestational age?

271-300 d