34. Dystocia in gilts & sows (aetiology, pathogenesis, clinical signs, diagnosis, differentials, treatment, prevention)

What is the mean gestation length of sows on most farms?

114 to 115 days with a standard deviation of 1.5 days

When do most sows typically farrow?

At night

What behavioural change occurs in a sow within 24 hours before parturition?

The sow becomes restless and shows bed-making behaviour

What is the method to synchronise parturition in sows, and when is it administered?

Injection of 19 mg PGF2a (destroy CL) IM at 112-113 days of gestation. Farrowing 28 hours later

What can increase the effect of PGF2a synchronising parturition in sows?

Administering estradiol 1 day before or 5 hours later

What is the first stage of parturition in sows characterised by?

Uterine contractions and cervix dilation, lasting 12-24 hours

What characterises the second and third stages of parturition in sows?

Abdominal contractions resulting in the expulsion of the foetus and foetal membranes, lasting 0.5-4 hours; piglets delivered at intervals of 15-20 minutes

What is dystocia in sows?

Difficult, slow, or abnormal farrowing occurring in less than 3% of all farrowings, more common in primiparous and older sows

What are key signs of dystocia in sows?

• Failure to deliver piglets within an hour or two of the onset of labour or an interval longer than 1 hour between deliveries

• Prolonged gestation beyond 116 days, illness (anorexia, depression), and discoloured or fetid vulvar discharge

What are the two main categories of dystocia causes?

Maternal and foetal causes

What can contribute to maternal dystocia?

• Lack of expulsive forces

• Abnormalities in the soft-tissue or bony sections of the birth canal

What anatomical feature predisposes sows to dystocia?

The long body and cervix of the uterus surrounded by bony and soft tissue (rectum, bladder)

What are examples of causes of dystocia?

1. Uterine intertia

2. Obstruction

3. Downward deviation of the uterus

4. Foetopelvic disproportion

5. Foetal malposition

6. Maternal excitement

What is uterine intertia?

Failure of the uterus to expel a foetus normally.

Uterine inertia can be primary, secondary or idiopathic

What is primary uterine inertia in sows?

Failure to begin the second stage of labour (no contractions), often due to hormonal or nutritional abnormalities.

Sows may be toxaemic or non-toxaemic

What are the characteristics of toxaemic sows during parturition?

Signs of illness, foul-smelling vaginal discharge with a ‘dead pig odour’

What are the characteristics of non-toxaemic sows during parturition?

Bright and alert, cervix dilated or easily dilatable, palpable foetuses, but no uterine contractions

What is secondary uterine inertia in sows?

More common. Occurs when abdominal pressing and myometrial contractions against an obstructed birth canal lead to fatigue and exhaustion

What can cause secondary uterine inertia?

Dead, malposition, simultaneous presentation of two or more piglets, obstruction of the birth canal

What is idiopathic uterine inertia in sows?

Farrowing commences normally but stops due to a cessation of uterine contractions, often in fat sows or those with low calcium levels

What can cause obstruction during parturition in sows?

1. Bony tissue abnormalities (e.g., fractures, disease)

2. Soft tissue abnormalities (e.g., congenital defects, vulval constriction)

3. Partial occlusion (e.g., excessive fat deposits, full urinary bladder, constipation/excessive faecal matter in rectum)

What is downward deviation of the uterus in sows?

A condition common in older prolific sows where the uterus deviates ventrally towards the abdominal floor, making manual removal difficult

What is foetopelvic disproportion in sows?

A mismatch between the size of the foetus (too large) and the maternal pelvis (too small) that causes obstruction during delivery.

Can be absolute or relative.

What is the difference between absolute and relative oversize in fetopelvic disproportion?

• Absolute oversize: maternal pelvis is normal size but foetus is too large

• Relative oversize: foetus is normal size but maternal pelvis is too small

What are the clinical signs of a sow in dystocia with foetopelvic disproportion?

Toxaemia- foul discharge, straining, cessation, prolonged farrowing (>2,5 hr- depends on litter size & age of sow), small litter size (embryonic/foetal mortality), retained placenta (nb same number of placentas as piglets)

What is the typical presentation of piglets during parturition?

Cranial presentation (head first) or caudal presentation (rear legs first)

What are examples of foetal malposition?

1. Breech

2. Transverse/sideways

3. Poll presentation

4. Two foetuses

What is breech presentation in sows?

When the foetus is presented backward or tail first, which can impede normal delivery. But all malposition or malpresentation are considered breech.

What is transverse or sideways position during parturition in sows?

When the body of the fetus is flexed at the backbone or side, becoming lodged in the birth canal

What is poll presentation during parturition in sows?

When the foetus comes head-first but the neck is flexed, causing the top of the head to become lodged in the birth canal

What effect does maternal excitement have on parturition in gilts?

It can cause delay and may be accompanied by aggression towards the litter

What drug can be used to sedate gilts experiencing maternal excitement?

• Azaperone (IM 2 mg/kg)

• Can be supplemented with 20IU IM Oxytocin (if no malposition)

What is the obstetrician's checklist for assessing parturition in sows?

1. History

2. General examination

3. Vaginal examination

4. Determination of the end of birth process

5. Aftercare of piglets and sow

6. Surgical removal of piglets if necessary

What should be noted in the history when assessing parturition?

Duration of parturition, number of piglets, dead piglets

What should a general examination of a birthing sow involve?

General appearance, TPR, signs of heat stroke, vulval examination, udder

What should be checked during a vaginal examination of a sow?

Hygiene, lubrication, uterine tone, number of piglets, damage to the birth canal, presence and disposition of piglets

What actions should be carried out depending on uterine tone during parturition?

1. Good tone: wait 10 minutes

2. Poor tone: administer oxytocin to stimulate contractions

How should a foetus be manually removed?

If head first grab beneath chin & head, if rear first place two fingers above hamstring. Removal of placental tissues by gentle traction

How can the end of the birthing process be determined?

Check by internal ballottement or check closure of cervix. Behavioural signs may be misleading

What is important for the aftercare of piglets?

1. Respiration (shake it, stimulants, blow into mouth)

2. Heart rate

3. Tie umbilical cord

4. Colostrum

5. Clip/grind incisors

6. Tail docking (if necessary!)

7. Identification marking (ear notch, tag, tattoo)

8. Iron & vitamins (3-5 days)

9. Regular weighing

10. Castration

11. Weaning at 3-5 weeks

What is involved in the aftercare of the sow?

1. Vaginal exam (check for damage)

2. Udder (milk supply)

3. ATB

4. NSAIDs

NB: PPDS. Proper environment

What are the methods for surgical removal of piglets?

1. Foetotomy/embryotomy

2. C-section

What is fetotomy and when should it be used?

The method of dividing a foetus into pieces for easier passage through the birth canal; used only if the foetus is dead and not commonly indicated in sows

When is a C-section indicated in sows?

When the foetus is alive and in cases of foeto-pelvic disproportion, obstruction of the birth canal, uterine torsion or non-responsive uterine inertia