1

Methods for Improving Pre-Weaning Survival Rates of Piglets:

II. Farrowing and Dystocia

Jeffrey Wiegert1

and Mark Estienne2

1Department of Animal and Poultry Sciences and

2Tidewater Agricultural Research and

Extension Center, Virginia Tech

INTRODUCTION

Knauer and Hostetler (2013) concluded that increased sow productivity in the U.S. between

2005 and 2010 occurred primarily as a consequence of improved management and genetics. The

researchers examined data representing annual production by approximately 1.8 million sows,

and reported increases in total litter size and pigs born live. Although the number of pigs weaned

increased as well, the percentage of pigs that died before weaning was relatively constant

between 2005 and 2009, and actually increased from 2009 to 2010. Those data do not represent

all pig farms in the U.S. and may or may not be applicable to many small-scale and niche market

operations. They do suggest, however, that there is potential for further increasing sow

productivity by decreasing pre-weaning mortality.

Pre-weaning mortality in piglets may be interpreted as a welfare concern, and certainly

represents a large economic loss for the producer. In fact, some estimates place the average value

of each newborn piglet at just under $25 (Lay et al., 2002), although this may vary greatly

according to breed, season, input costs, and current market prices. Producers with high pre-

weaning mortality wean fewer pigs per sow per year and miss the opportunity to capitalize on

good breeding herd performance (e.g., high farrowing rates, large litter sizes, etc.). Maximizing

pre-weaning survivability, which is the percentage of piglets born alive that survive to weaning,

then becomes one of the most important production goals of the sow farm.

This paper is the second in a three part series addressing methods for improving pre-weaning

survivability in pigs and focuses on techniques to be employed during and immediately

following farrowing. Emphasis will be placed on how to properly assist sows during difficult

farrowings.

Persons who wish to be added to, or deleted from, the Small-Scale and Niche Market Pork

Producers electronic mailing list should notify Mark Estienne at mestienn@vt.edu.

Small-Scale and Niche Market Pork Production Bulletin No. 5; February 6, 2015 Virginia Tech- Tidewater Agricultural Research and Extension Center, Suffolk, VA

2

METHODS FOR IMPROVING PIGLET SURVIVAL

Indications that farrowing is imminent

Recognizing signs that farrowing is imminent is necessary to prepare for pig arrival. Physical

and behavioral changes associated with farrowing, as well as approximate times from expression

of behavior to commencement of farrowing, are presented in Table 1. Streaming milk from the

teats is the most reliable indicator that farrowing will soon occur. Sows with good milk letdown

will begin farrowing within 12 to 24 hours, and often sooner.

Table 1: Indications of impending farrowing and approximate time until farrowing

Physical / Behavioral Indicators Approximate Time Until Farrowing

Nest Building Behavior1

48 to 72 hours

Restlessness and Agitation 48 hours

Milk Drops (i.e., udders fill with milk) 24 to 36 hours

Vulva Swelling 12 to 24 hours

Streaming Lactation (i.e., milk dripping from teats) 12 to 24 hours

Increased Respiration Rate2

24 hours

Uterine Contractions less than 2 hours

Expulsion of Fluids and Meconium (feces from

fetuses)

less than 1 hour

1If provided with suitable substrate, such as straw, sows will attempt to use the substrate to build a nest.

In “barren” environments (e.g., farrowing crate situated on a concrete floor) the nest building behavior is

manifested in such activities as pawing at the floor. 2Range of respiration rates (breaths per minute) for sows at 24, 12, and 6 hours pre-farrowing are 35 to

45, 75 to 85, and 95 to 105 (Straw and Meuten, 1992).

Dystocia

Occurrences of dystocia (difficult, impeded, or abnormal birth) are relatively uncommon and

occur at a rate of approximately 3% in properly managed sows (Runnels and Clark, 1992).

However, when dystocia does occur high piglet death loss may result. Dystocia will extend the

duration of farrowing and piglets may die in the reproductive tract due to suffocation, or after

delivery due to the combined effects of oxygen deprivation and physical injuries and/or delayed

colostrum intake.

The birthing interval is the amount of time that passes from the birth of one piglet until the

birth of the next piglet or presentation of placentae (tissues that surround fetuses in the uterus).

Normal birthing interval is approximately 20 to 30 minutes. Some variation in the birthing

interval, particularly at the beginning and end of farrowing, should be expected. A birthing

interval exceeding one hour is abnormal, and may indicate dystocia.

The leading causes of dystocia in swine, as well as symptoms and appropriate methods of

treatment, are presented in Table 2. Correctly diagnosing the cause of dystocia is necessary to

determine the proper treatment. Treatment methods may be hormonal or physical depending on

the cause of dystocia.

3

Table 2. Causes of dystocia, symptoms and recommended treatment for sows (Sherrie Clark-

Deener, D.V.M.; Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg;

personal communications)

Cause Percentage of Cases Symptom Treatment

Uterine Inactivity 37 Weak or Absent

Contractions

Treatment with

Oxytocin

Incorrectly Positioned

Fetus

33 Strained Contractions Physical Intervention

Obstruction of Birth

Canal

13 Strained Contractions Physical Intervention

Abnormal Uterus 10 Normal Contractions

but No Piglet Birth

Physical Intervention

Size of Fetus too Large

for Size of Sow Pelvis

4 Strained Contractions Physical Intervention

Maternal Excitement 3 Restlessness and

Irritability

Stimulate Lactation /

Remove Distractions

Hypocalcemia (low

blood levels of calcium;

also called “milk fever”)

Less than 1 Instability or

Inability to Stand

Injectable Calcium

(under guidance by

veterinarian)

Hormonal Treatment. Oxytocin is a protein hormone that is secreted from the pituitary gland, a

garden pea-sized organ lying just below the brain. Among its functions is the excitation of

smooth muscle fibers in the uterus and mammary glands. In this way, it is responsible for both

uterine contractions during farrowing and later, for lactation.

Blood concentrations of oxytocin increase immediately prior to farrowing. Massaging the

sow’s underline, hand-milking individual nipples, and encouraging piglet suckling will increase

oxytocin demand in the mammary and stimulate secretion from the pituitary gland. The

resulting secretion of oxytocin into the bloodstream makes the hormone available for use by the

uterus, and may expedite a slow farrowing. However, sows with weak contractions, no

contractions, or long birthing intervals during the latter-half of farrowing may benefit from

oxytocin treatment.

Indeed, if uterine contractions do not resume following mammary stimulation as described

above, administration of exogenous (i.e., injectable) oxytocin may be appropriate. Always check

the birth canal for signs of obstruction before giving oxytocin. Do not administer oxytocin if a

piglet is stuck in the birth canal. The increased pressure from strengthened uterine contractions

may rupture the umbilical cord of the trapped piglet. Without oxygen from the blood carried in

the umbilical cord, the pig will die of suffocation and be farrowed stillborn.

Following are some notes regarding the proper use of oxytocin:

The dose of oxytocin typically recommended is 0.5 cc (10 I.U.), given intramuscularly

or injected into the vulva.

Oxytocin should not be administered until after the sixth piglet is born.

4

No more than two injections of oxytocin should be given during a single farrowing

event. The second injection should be given approximately 30 minutes after the first,

and only if contractions do not resume following the first injection.

Overdosing of oxytocin will induce a refractory period of up to three hours during

which hormone receptors become desensitized to both internally produced and

externally injected oxytocin. Uterine contractions and milk letdown may cease during

this time.

Oxytocin requires a veterinary prescription.

Physical Intervention (Sleeving). Better known as sleeving, physical intervention is the act of

palpating the uterus to manually remove a blocked or incorrectly positioned fetus. Dams with

stuck piglets will appear distressed and may vocalize and change positions often. Some fluid and

meconium (feces from fetuses) discharge will likely be present as well.

Palpating the uterus is an invasive process and carries the risk of irritating the reproductive

tract, disrupting normal contractile rhythms, and introducing foreign contaminants. Any injuries

or infections associated with sleeving may decrease subsequent feed intake and milk production

and if left untreated, may cause long-lasting disease, decrease future reproductive performance,

or, in extreme cases cause death of the sow. Adherence to proper sleeving technique should be

followed on every occasion.

A step-by-step procedure for sleeving is provided below:

1. Remove all jewelry (rings, watches, etc.) from the arm to be sleeved. Persons with long

fingernails should not sleeve a sow.

2. Sleeve the arm corresponding to the side on which the sow is lying. For example, if the

sow is lying on her right side, the producer should sleeve with their right arm.

3. Wear a clean shoulder-length obstetrical glove and lubricate the glove generously. Take

care not to contaminate the glove before entering the sow.

4. Lubricate the vulva and vagina before entering the sow.

5. Enter the vagina with fingers together and pointed forward. Keep the thumb tucked into

the palm when entering and while inside the reproductive tract.

6. Grasp the piglet gently, but firmly, using an appropriate grip. Pictures representing

appropriate grips for front-facing and back-facing pigs are presented in Figure 1.

7. Pull pig out at a slight ventral angle (towards the sow’s feet) to minimize pelvic

resistance.

5

8. Immediately re-enter the sow to remove other piglets whose birth may have been

blocked.

9. Continue sleeving every 25 minutes or until normal farrowing resumes.

Closely monitor assisted sows for a minimum of three days following farrowing, as they may

suffer lameness, pelvic inflammation, vaginal/uterine infection, loss of appetite, and/or decreased

milk production. Contact a veterinarian if any of the following symptoms appear: feed and water

refusal, inconsistency in urination and defecation, off-color urine, greater than normal pus and

mucus discharge, or black and bloody discharge from the vulva. A veterinarian may prescribe

antibiotics, drugs for pain mitigation and/or drugs to decrease swelling.

Savaging. During and immediately following farrowing, gilts and sows will occasionally attack

and kill their newborn piglets. Maternal infanticide, better known as savaging, is relatively

uncommon and often overlooked in pig production, but in extreme cases can be responsible for

10 to 25% of total pre-weaning mortality (Spicer et al., 1986; Ahlstrom et al., 2001; Harris and

Gonyou, 2003). Survey data collected and submitted by employees of commercial farrowing

farms in central Canada indicated that 5.3% of first-parity gilts show some degree of aggressive

behavior towards their offspring, with 2.9% of gilts fatally attacking one or more piglets (Harris

and Gonyou, 2003). It is likely, however, that these values underestimate the true occurrences of

piglet-directed aggression, as gilts in the study were observed only sporadically throughout the

workday and no observations were made in the evening and nighttime hours. Other reports have

suggested piglet-directed aggressive behaviors in up to 15% of dams (Turner, 2011).

The exact reason why gilts and sows savage their piglets is unknown. One could speculate

that gilts associate their unfamiliar birthing pain with their newborn piglets and attack them out

of fear or anger. In reality, the true cause of savaging is likely not that simple, and may in fact be

the result of many factors. For example, even though confinement farrowings (i.e., in farrowing

crates) statistically yield the highest total pre-weaning survivability (Blackshaw et al., 1994),

incidences of savaging are typically increased in farrowing crates when compared to loose-

housing farrowing systems (Cronin et al., 1996). Other factors, such as social stress (pen-mixing

stress) during mid-gestation and discomfort or unfamiliarity with the farmer or farrowing

technicians may increase the expression of savaging behaviors. Providing environmental

enrichment (e.g., straw bedding) and continuous lighting during farrowing has been shown to

decrease both the incidences of savaging and the number of piglets killed by savaging (Harris

and Gonyou, 2003; Ringgenberg et al., 2012).

6

Figure 1: Appropriate grips for sleeving piglets (National Hog Farmer, 2012)

Over-the-Head Technique

Thumb-in-Jaw Technique

Hock Technique

7

Gilts that attack their piglets should be culled from the breeding herd. Harris et al. (2003)

reported that 14% of sows that showed savaging behavior in their first litter expressed similar

behaviors in subsequent farrowings, while less than 1% of sows that did not savage their first

litter showed savaging behavior in later farrowings. Studies reviewed by Turner (2011) showed

some success in decreasing savaging events after placing selection pressure against the trait (i.e.,

culling savage gilts and selecting replacement gilts from females with docile temperaments).

When gilts or sows are displaying aggressive behaviors towards their newborn offspring,

pigs should be removed from the farrowing area and kept in a warm and dry holding area until

the risk subsides and it is safe to reintroduce them with the dam. Usually, savaging behavior

stops once farrowing has concluded and consistent nursing begins.

24/7 Farrowing Supervision

Supervised farrowings may be the most beneficial management strategy for improving

piglet survivability. Producers who provide continuous farrowing care are better prepared to

assist with dystocia, respond to the cries of injured piglets, remove placenta from the heads of

suffocating pigs, dry off newborns, encourage suckling and colostrum consumption, and adjust

fans and heat sources to better regulate the environment. Indeed, large increases in pre-weaning

survivability are achieved when farrowings are attended by a trained and competent individual

(Britt, 1986). Large decreases in the number of stillborn pigs is often seen as well, suggesting

that many dead pigs classified as “stillborn” by the producer were in fact live-born animals that

could have lived to weaning had they received timely assistance (White et al., 1996).

In one study, the simple act of towel-drying and placing neonatal piglets under a heat source

improved piglet survivability, decreased the number of stillborn pigs, and decreased the number

of pigs crushed by maternal overlay (Andersen et al., 2009). Litter size at weaning and

individual pig weaning weight may also be improved by providing individual pig attention

during farrowing (White et al., 1996).

Attending all farrowings is time and labor intensive, and may not be feasible for many small-

scale producers. To some extent, the timing of farrowing can be controlled by use of

commercially available prostaglandin-F2α (PGF2α) products such as Lutalyse1 (Zoetis, Inc.;

Kalamazoo, MI). Intramuscular injection of 2 mL (10 mg) of Lutalyse causes farrowing in sows

approximately 30 hours later, and is a potentially useful strategy to coordinate timing of

farrowing with labor availability. For example, pregnant sows could be injected with Lutalyse at

say 9:00 a.m. on Monday, resulting in most sows farrowing Tuesday afternoon. Producers

desiring to use this technology must know exact breeding dates and the average length of

gestation for their herd, and only inject Lutalyse within three days of normal farrowing.

For example, if average length of gestation in your herd is 115 days, then Lutalyse should

not be administered before day 112 of gestation. Otherwise, piglets may be born immature and

with low viability. Research has shown that litters from sows that were induced to farrow with

1 Mention of a trade name or proprietary product does not constitute a guarantee or warranty by

Virginia Tech and does not imply its approval to the exclusion of other products which may be

suitable.

8

PGF2α and attended by a trained individual showed decreased mortality rate and number of

stillborn pigs when compared to non-induced and unattended litters. Further, average litter

weight was greater in induced and attended farrowings on both three days and twenty-one days

post-farrowing (Nguyen et al., 2010).

CONCLUSION

Focusing on pig health and well-being during and immediately following the process of

farrowing will decrease pig mortality rates and stillbirth percentages while increasing the number

of pigs weaned per sow per year. These strategies, though, are time and labor intensive,

particularly on small-scale farms, and producers will need to assess the costs and benefits of their

application. Increased animal welfare resulting from improved piglet survival should be

considered, as well. A few points to bear in mind throughout farrowing that may improve piglet

pre-weaning survivability are:

Be able to recognize the physical and behavioral indicators of impending farrowing.

Know how and when to intervene and assist with difficult farrowings.

Have any necessary equipment, drugs, and medicines ready to be used in the event of

dystocia.

Cull gilts that savage piglets or that show piglet-directed aggression.

During farrowing by savaging gilts or sows, be prepared to move at-risk pig to safety.

If possible, attend every farrowing and provide maximum individual piglet attention.

REFERENCES

Ahlstrom, S., S. Jarvis, and A.B. Lawrence. 2001. Savaging gilts are more restless and more

responsive to piglets during the expulsive phase of parturition. Applied Animal Behaviour

Science 76:83-91.

Andersen, I.L., I.A. Haukvik, and K.E. Boe. 2009. Drying and warming immediately after birth

may reduce piglet mortality in loose-housed sows. Animal 3:592-597.

Blackshaw, J.K., A.W. Blackshaw, F.J. Thomas, and F.W. Newman. 1994. Comparison of

behaviour patterns of sows and litters in a farrowing crate and a farrowing pen. Applied Animal

Behaviour Science. 39:281-295.

Britt, J.H. 1986. Improving sow productivity through management during gestation, lactation and

after weaning. Journal of Animal Science 63:1288-1296.

9

Cronin, G.M., G.J. Simpson, and P.H. Hemsworth. 1996. The effects of the gestation and

farrowing environments on sow and piglet behaviour and piglet survival and growth in early

lactation. Applied Animal Behaviour Science 46:175-192.

Harris, M.J. and H.W. Gonyou. 2003. Savaging behavior in domestic gilts: A study of seven

commercial farms. Canadian Journal of Animal Science 83:435-444.

Harris, M.J., Y.Z. Li, and H.W. Gonyou. 2003. Savaging behavior in gilts and sows. Canadian

Journal of Animal Science 83:819-821.

Knauer, M.T. and C.E. Hostetler. 2013. US swine industry productivity analysis, 2005 to 2010.

Journal of Swine Health and Production 21:248-252.

Lay, Jr., D.C., R.L. Matteri, J.A. Carroll, T.J. Fangman, and T.J. Safranski. 2002. Preweaning

survival in swine. Journal of Animal Science 80:E74-E86.

National Hog Farmer. 2012. See what you feel – an assisted farrowing guide. Available at:

http://nationalhogfarmer.com/reproduction/see-what-you-feel-assisted-farrowing-guide#slide-0-

field_images-13891. (Accessed December 8, 2014).

Nguyen, K., G. Cassar, R.M. Friendship, C. Dewey, A. Farzan, and R.N. Kirkwood. 2010.

Stillbirth and preweaning mortality in litters of sows induced to farrow with supervision

compared to litters of naturally farrowing sows with minimal supervision. Journal of Swine

Health and Production 19:214-217.

Ringgenberg, N., R. Bergeron, M. Meunier-Salaun, and N. Devillers. 2012. Impact of social

stress during gestation and environmental enrichment during lactation on the maternal behavior

of sows. Applied Animal Behaviour Science 136:126-135.

Runnels, L.J. and L.K. Clark. 1992. Obstetrics. In: A.D. Leman, B.E. Straw, W.L. Mengeling, S.

D’Allaire, and D.J. Taylor (ed.). Diseases of Swine. Pp. 925-932. Iowa State University Press,

Ames, IA.

Spicer, E.M., S.J. Driesen, V.A. Fahy, B.J. Horton, L.D. Sims, R.T. Jones, R.S. Cutler, and R.W.

Prime. 1986. Causes of preweaning mortality on a large intensive piggery. Australian Veterinary

Journal 63:71-75.

Straw, B.E. and D.J. Meuten. 1992. Physical Examination. In: A.D. Leman, B.E. Straw, W.L.

Mengeling, S. D’Allaire, and D.J. Taylor (ed.). Diseases of Swine. Pp. 793-807. Iowa State

University Press, Ames, IA.

Turner, S.P. 2011. Breeding against harmful social behaviours in pigs and chickens: State of the

art and the way forward. Applied Animal Behaviour Science 134:1-9.

10

White, K.R., D.M. Anderson, and L.A. Bate. 1996. Increasing piglet survival through an

improved farrowing management protocol. Canadian Journal of Animal Science 76:491-495.