Swine Theriogenology

Phillip G. Hoyt, DVM
Course # 5326
Fall 1998


American College of Theriogenologists and Society for Theriogenology and American Association of Swine Practitioners. Proceedings of Swine Reproduction Symposium, August, 1996.

Kirkwood, R.N.; Thacker, P.A.: Increasing Reproductive Performance. Large Animal Veterinarian, pp. 26-32, September / October 1988

Kirkwood, R.N.; Thacker, P.A.: Gilt Management Tips. Hog Farm Management, pp. 25-28, May 1988

Almond, G.W.; Dial, G.D.: Pregnancy Diagnosis in Swine: Principles, Applications, and Accuracy of Available Techniques. JAVMA, 191(7):858-870, Oct. 1, 1987

McDonald, L. E.: Veterinary Endocrinology and Reproduction, 1971

Pond, W. G.; Houpt, K. A.: The Biology of the Pig

Pond, W. G.; Maner, J. H.: Swine Production in Temperate and Tropical Environments

Wrathall, A. E.: Prenatal Survival in Pigs: Part I

Wrathall, A. E.: Reproductive Disorders in Pigs

Marrow, D.A.: Current Therapy in Theriogenology

Reproductive Examination of the Boar. Journal of the Society for Theriogenology, Volume XIII

In a 1981 Swedish study done by Ehnval et al on 2041 replacement gilts the reasons for culling were listed.

Reason for Number of Percentage of Culled in percent
culling culled gilts culled gilts of recruited gilts

Slow growth rate 162 14.6 7.9

High backfat
thickness 308 27.7 15.1

High backfat
thickness and
inverted teats 76 6.8 3.7

Inverted teats 130 11.7 6.4

Anestrus 122 11.0 6.0

Repeat breeding 34 3.1 1.7

Not Pregnant 73 6.6 3.6

Abortion 11 1.0 .5

Miscellaneous 196 17.6 9.6

Total 1112 100.1 54.5

54.5% of the recruited gilts were culled.

21.7% of the culls were due to reproductive problems.

Up until 9 months of age, the majority were culled because of slow growth rate, high backfat thickness, and inverted teats.

After 9 months of age 66.9% of the culls were because of reproductive failure.
34% of these because of anestrus. Delayed puberty was the dominating reason.

6% of all gilts were culled because of anestrus.


Predictable gilt breeding activity
12 strong normal pigs
100% survival to weaning
Prompt conception after weaning
Litters and pigs per sow per year:
114 day gestation
21 day lactation
5 day rebreeding 365 = 2.6 litters per year
140 day farrowing interval 140

Pigs weaned per litter = 12
2.6 X 12 = 31.2 pigs weaned per sow per year

Main reasons for poor reproductive performance:
Late puberty Boar locomotor, behavioral , and infertility problems
Low conception rates Pregnancy loss from abortions and pseudopregnancy
Seasonal infertility High culling rate among sows and boars
Small litter size Undetected nonpregnant sows
Preweaning loss Perinatal (shortly after birth) loss

Records needed to evaluate the performance:
Matings per week Monthly breeding herd inventory
Boar usage charts Litters per sow per year
Litter size Pigs weaned per litter
Percentage of females in heat 7 days postweaning

Slaughter checks of culled breeding stock:
Cycling animals (CL and/or large follicles)
Inactive ovaries (no CL and small follicles)


Double mating a sow at 12-24 hour intervals:
Increases conception rates
Using different boars masks a boar with low fertility
1-2 extra pigs per litter

Pen mating:
1 boar or more in a group of sows for 23-45 days
1 boar per 8-10 sows for continuous farrowing
Rotate boars every 8-24 hours for double mating benefits
Can't identify bred females
Can't observe mating behavior
Can't identify the sire of the offspring
In large groups, some sows may not get bred
Mask boars with poor libido or depressed mating ability

Pasture breeding:
Very similar to pen mating
Being replaced because of confinement

Hand mating:
Estrus sows taken to breeding pen
Advantages: Disadvantages:
Close observation of mating behavior Good heat detection (Essential)
Accurate breeding dates May require a vasectomized boar
Controlled multiple matings Labor intensive
Control of boar usage

Artificial insemination:
Advantages: Disadvantages:
Few boars needed Similar to hand mating
Use of higher quality boars Very labor intensive
Equipment needs

Number of boars needed depends on:
Age of boars Mating system
Libido Lameness incidence
Breeding pen size Season of the year
Weaning practices Initiate puberty in gilts and heat detection

Two uterine horns:
Each pregnant uterine horn one meter or more in length
Very tortuous

External orifice small with overlapping folds
Spiral tip of penis penetrates 1-2 rings

Many corpus luteum formed
Both function at same time
Left ovary ovulates 55-60% of ova

Uterotubular junction:
Not clearly defined
Not a true sphincter
Mucosal folds swell at the end of estrus

Epithelial-chorial placentation:
Six layers separate maternal and fetal blood
Endothelium - Connective Tissue - Epithelium - Chorian - Connective Tissue - Endothelium
Diffuse attachment

Approximately 200 days of age (150-250 days) (breed differences):
Landrace earlier than Yorkshire
Durocs are the latest
Crossbreeds reach puberty earlier

Delay puberty:
Severely limiting feed intake
Normal limit feeding doesn't delay puberty
Vitamin B12 deficiency
Protein deficiency
Full feeding
Excessively fat gilts
Season of the year
Decreases number of gilts reaching puberty by 8-9 months 40-50%
Increases age of puberty by 30-60 days
Lighting (total darkness)

Hasten puberty:
Large breeds and crossbreeds
Presence of boar:
Gilts cycle up to 40 days sooner
When the gilt reaches 170-190 days of age
House gilts in groups
Transport stress:
Changing pens
Mixing with new penmates
18 hours of light and 6 hours of darkness ideal
Intensity (10 - 20 candles is ideal)

Polytocous (litter) and nonseasonal polyestrus
Average length of 21 days (19-23):
Breed differences
High environmental temperature has no effect on length
Silent heats occasionally occur
1-3 days
Alert to boar's approach, but will not let boar mount
Mounts other sows & accepts mounting by other sows
3-4 days but sow mates for only 2-3 days
Red swollen vulva and vaginal discharge
Extreme restlessness and spontaneous activity (fence walking, follow moving objects)
Mounts other animals & frequent mounting by other sows
Frequent urination
Will seek out boar
Mating stance (immobility reaction)
All 4 legs locked in extension
Ears cocked
Stimulated by:
Pressure on back or rump
Olfactory (boar pheromones)
Auditory (boar sounds)
Visual and tactile stimuli lessor role
2 days
Very similar to diestrus
14 days
Boar fiercely rejected

Poor success with the vaginal smear in detecting cycle stage
Corpus luteum fully developed 7 days after start of estrus
CL progesterone decreases 14 days after estrus starts
CL regression starts 15 days after estrus starts
Reproductive life of many years

Occurs spontaneously from mid to late estrus:
Last 1/3 of estrus (36-40 hours after estrus onset)
Breed differences
Duration usually about 2 hours (extends to 6-8 hrs.)

Ovulation rate:
Mature sows between 15-20 (17) ova
Gilts between 10-15 (13) ova
Breed differences
40-50% heritability
Increase ovulation rate:
Flushing gilts 2 weeks prebreeding (questionable in sows)
Older gilts:
10 days older equal .5 CL more
Puberty through first 4-5 estrus cycles
1 - 2 more pigs / litter when bred on the 2 - 3 heat
Heavier gilts at weaning and breeding
Decrease ovulation rate:
High environmental temperature
Age of sow (fewer ova in gilts)

Considered an all or none response (Several billion sperm and fewer than 24 ova)
Percent fertilization after mating and ovulation:
24% after 2-3 hours
72% after 5 hours
100% after 8-14 hours
Ova fertile for 24 hours after ovulation
Breed during first half of estrus:
10-25.5 hours after start of estrus is optimal
Second AI from 36-38 hours after standing heat starts
12 hours after onset is best for sows
Sperm transport:
Uterotubular junction in 10 minutes
Number of sperm in oviduct not affected by live or dead sperm
Sperm motility drastically reduced after 2 hours
Sperm viable for 25-30 hours in oviduct
Lower fertilization rates with older sperm
Decreased embryonic survival with older sperm

Conception rate:
Percent of matings which result in viable fetuses
First service conception rates in gilts and sows:
70% acceptable
90% possible
Conception failure:
Abnormal anatomy Boar infertility
Cystic follicles Environmental temperature
Improper timing Diseases
Bacterial infection of reproductive tract or semen
Double mating
Heat stress reduces reproductive efficiency

Embryonic & fetal mortality:
30-40% fetal mortality between 1 and 114 day of gestation
Failure of fertilization is only 5-10% of prenatal loss
50% or more of losses during the first 25 days of gestation
Embryonic survival influences litter size more than ovulation rate
Intrauterine migration:
Migrate for up to 12 days
Must be at implantation site by day 13
Embryos in each horn from 10 to 12 days (after 12 days not needed)
Day 12:
Need at least 4 embryos
Less than 4 embryos causes sow to recycle in 25-27 days
Day 30:
2 live embryos needed to maintain pregnancy
Increased embryonic death:
High plane of nutrition immediately after breeding
Large litters from excess progesterone from number of CL
Starvation of gilts beyond 41 days without exogenous progesterone and estradiol
High environmental temperature (summer infertility)
Limits embryos that survive the first month of gestation (mechanism is unknown)
After 30 days space may be a problem (exceed 14 embryos)
Considerable loss
Fetal death after 40 days
More prevalent in large litters
Increase during last 1/3 of farrowing
Increase in large litters

Pregnancy detection:
Failure to show estrus 21 days after breeding
Ultrasound at 30-90 days of gestation (film SVM library)
Rectal palpation (difficult on gilts)
Complete list: Almond, G.W.; Dial, G.D.: Pregnancy Diagnosis in Swine: Principles, Applications, and Accuracy of Available Techniques. JAVMA Oct. 1, 1987; 191(7):858-870.

Average of 114 days (3 months, 3 weeks, 3 days)
Domestic pigs 10 days shorter than feral pigs

Litter size:
Depends on:
Number of ova produced
Percent fertilization
Degree of prenatal mortality:
Number of stillborn
Number of mummies
Number of embryonic death
Maximum during 4-7 litter
Gilts farrow an average of 1-2 pigs less:
Second and subsequent litters larger with bigger pigs
1 - 2 more pigs / litter if gilts bred on 2 - 3 heat
60-70% of ova ovulated
Small litters associated with a marginally fertile boar
Breed differences
Frozen semen decreases number of live pigs

Induction of parturition:
Avoid weekend and holiday farrowing
Equalize litter and pig sizes
Better crate utilization
Uniform post weaning estrus
10 mg at 112 days & 60-90% farrow in 18-36 hours (28 hrs)
Before 112 days = small pigs and low survival
After 112 days = less synchronization
Give at 8:00 AM and sows farrow next day
Oxytocin (doesn't always work)
Corticosteroids (decreases neonatal survival)

Parturition (Farrowing):
Behavioral changes:
Fetal adrenal glands important in onset
Duration from 1-2 hours to 24 hours (4 +/- 30 minutes)
Rules of thumb:
2 hours for first pig
Pig every 1/2-1 hour (19 min.)
Examine sow if times are longer
Placentas passed when finished
One or more pigs before any placenta
Head or rear feet first are normal presentations (65% head first)
Umbilical cord still attached at birth (pig breaks after birth)
Obstetrical care: (Minimal usually)
Good sow survival if labor less than 6 hours
Decline in sow survival with longer labor
Artificial respiration:
Clean mucus from pig's nose
Make loose fist with hand
Pig's nose pushed up behind thumb and trigger finger
Blow through thumb and trigger finger

Select replacements with 7 functional teats per side:
3 per side anterior to the umbilicus
No ovulation
Signs of heat may occur 1-3 days after farrowing (no ovulation)
Estrus and ovulation 3-14 days (5-10 days) after weaning:
8 week weaning = 5-7 days return to estrus
Shorter weaning = longer return to estrus
2 day weaning = 14 day return to estrus
Induce estrus by temporary removal of pigs (1 day)
Estrus synchronization by weaning

Milk supplementation:
Pig physiology:
Average duration on milk letdown is 28 seconds
Nurse every 65 minutes
32 hours to establish teat order
Recognize mother by three days
Commercial milk replacers available:
Cow colostrum: (Not good, but helps)
Freeze in ice cube trays
1 cube per pig every 1-2 hours

Control of the estrus cycle:
Weaning and heat in 5 - 14 days (Most common)
5 mg per sow
Given on day 12-13
PMS (400 IU) at weaning:
HCG (LH) (200 IU) or GnRH 96 hours later
Ovulation in 2 days
PMS (1200 IU) in cycling sows:
HCG (500-1000 IU) 96 hours later
Oral estrogens followed by progesterone in cycling sows
Oral dithiocarbanoylhydrazine derivative for 18-20 days:
PMS on day after drug removal
HCG 96 hours later
Gilts ovulate about 40 hours later
Low fertility (poor conception and small litters) with induced estrus:
Gilts should be bred at the following estrus
Many gilts fail to show a second estrus
Work in sows
Product available since March, 1990.
"P.G. 600" (400 I.U. PMSG and 200 I.U. HCG) IM
Fertile estrus in 3 - 10 days in 59% gilts which are non-cycling, 5 1/2 months old, and weighing >185 pounds
Will not work on cycling gilts or those under 5 1/2 months old or <185 #
Altrenogest ("Regumate"):
15-20 mg per day
18 days
Heat in 3-5 days

Embryo transfer:
Has been done
Superovulation by exogenous gonadotrophins (PMSG)
Surgical procedure
Fertilized ova transferred:
2-8 cell stage
Ova collected 5-6 days after mating are best
Blastocysts recovered on day 7-8 have produced pregnancy
Donors 1-2 days before or 1 day later than recipients


Failure to show heat or failure of heat detection:
Delayed puberty:
Infantile reproductive tracts
Seasonal anestrus:
July, August, and September in the U.S.A.
More infantile reproductive tracts in the late summer
More postweaning anestrus
Especially in first litter gilts and old sows
Sudden elevation of ambient temperatures
Negative nutritional balance
All fetuses reabsorbed
Hormonal pregnancy
Mammary development and maternal behavior
Prevalence and cause is not understood
Silent estrus:
Behavioral anestrus
Up to 30% of confinement gilts
Hormonal events occur
Estrus behavior doesn't occur
Presence of an active CL
Nonfunctional ovaries:
Confinement gilts
1-2 normal cycles and then anestrus
No infectious agents cause anestrus:
Clinical ill or debilitated animal not likely to cycle
Systemic disease
Chronic infections of the uterus and oviducts
Cystic ovarian degeneration (not common)
Poor boar libido:
Not anestrus
Owners call it anestrus
Management failure:
Missed estrus
Can't recognize estrus
Poor design of breeding area
Poor facilities making it difficult to move and observe animals

Return to estrus:
Prior to 25 days post mating
Failure to conceive
Embryonic death before day 12
Irregular (delayed):
After 25 days post mating
Pregnancy failure after day 12
Undetected because estrus detections stop after 40 days
Increase during July, August, and September
Infectious agents (parvovirus, brucellosis, etc.)

Pregnancy loss:
Difference between number farrowed and number bred or diagnosed pregnant
5-10% loss is accepted on most farms:
With ultrasound pregnancy diagnosis before 40 days
May reach 20% in the summer and fall

Maternal failure:
Systemic reaction (toxemia)
Febrile reaction (acute erysipelas, acute salmonellosis)
Few or no pathologic changes in fetus
Conceptus failure
Combination of both
22% viral causes:
16.5% bacterial and fungal causes (leptospirosis mainly)
61.5% undiagnosed
Seasonal pattern (late summer period of low fertility)
High carbon monoxide levels
Reproductive tract infections cause sporadic abortions:
Actinomyces (Corynebacterium) pyogenes
Pasteurella multocida
Staphylococcus aureus
Brucella suis:
Any stage of gestation
Occurs 30 days post exposure
Few signs in early abortions, just a return to estrus
Purulent vaginal discharge in later abortions
Well developed placenta required (after the second month)
Occurs 2-4 weeks after exposure
Diseased or dead pigs
Abortion storms
Pseudorabies and swine fever (viremia)
Environmental stress, fighting, and heat stress

5-7% of all pigs farrowed
Umbilical cord:
24-30 inches long (uterus 5-6 feet long)
After cord ruptures, the pig must be born in 5 minutes
Very low anoxic tolerance (hypoxia results in weak pigs)
Meconium in lungs and trachea and on the skin
Two types:
Type 1 die before parturition (can be infectious agents)
Type 2 die during parturition (usually noninfectious)
Infectious agents:
Brucella suis Parvovirus
Leptospira Enterovirus
Swine fever Pseudorabies
Estrogenic mycotoxicosis
Environmental factors:
Heat stress: (Temperature of 39 C or higher on days 102-110)
Increases number of stillborns
Decreases number of pigs
Decreases birth weights
Nutritional deficiencies
Infectious agents
High levels of carbon monoxide:
Gas heaters
Hemoglobin levels below 9 g/100 ml in sows:
Iron deficiency
Congenital abnormalities
Duration of farrowing:
1 hour = 2.4% stillborn
8 hours = 10.5% stillborn
Increase when 45-55 minutes between pigs
Increase in the last 1/3 of the litter
Litter size:
Increase in litters of <4 or >9

Death of fetus after 34 days of gestation (skeletal calcification)
Brown, dry, shriveled up fetus (leather)
Disintegration of fetus results in macerated fetus
Prolonged gestation length:
No fetal adrenals
Weeks passed due
Most commonly follows viral infections:
Parvovirus (most common)
Swine fever
Toxoplasma gondii (protozoan)

Often born alive
Survival depends on the severity
Occur between 14-25 days of gestation
Inherited congenital disorders:
Atresia ani Cranioschisis
Splayleg (questionable) Lumbar spinal defects
Various limb abnormalities Cleft palate
Nutritional deficiencies:
Vitamin A Calcium
Panothenic acid Iodine
Teratogenic agents (limb abnormalities):
Tobacco plant (Nicotiana tabacum) Jimson weed (Datura stramonium)
Hemlock (Conium maculatum)
Hormone-like substance:
Estrus synchronization of gilts
Malformed pigs if feed to pregnant sows
Viral infections:
Death or malformation depending on organ involvement
Type of malformation depends on which tissue involved

Low conception rates or repeat breeding:
80-85% farrowing rate in sows mated at first post weaning estrus
Fertilization failure or very early embryonic death
Low conception rates and small litters caused by boar and/or sow:
Sperm defects Toxins (estrogenic mycotoxins)
Heat stress (2 months) Musculoskeletal problems
Severe febrile condition Orchitis (Brucella suis)
Sow or gilt:
Anatomical abnormalities Viral diseases
Cystic ovarian disease Adhesions on oviduct or bursa
Metritis and endometritis
Return to estrus after 24 days:
Embryonic death 12 days or later after fertilization
Endocrine disturbances (ovarian cysts)

Long post-weaning estrus interval
Few problems unless severe restriction post mating
If pig birth weight doesn't drop below 1 kg, no effect on survival
Increases early embryonic death
Fat sows
Protein deficiency:
Increases weaning to estrus interval esp. in gilts
Maintain pregnancy but a 20-25% decrease in birth weight
15% protein lactation ration sufficient for reproduction
Ration quality and quantity after weaning affects ability to return to estrus and conceive:
High nutrition post weaning reduces interval and variability of return to estrus (esp. gilts)
High levels to sows post weaning (higher percentages show heatin 7 days)
No severe effect on boars:
Deficiencies can alter his health and well being
Don't want a fat boar

Reproductive abnormalities:
Extreme muscling:
Delayed puberty Poor mothering ability
Low conception rate Pick gilts for soundness and reproduction
Farrowing difficulty
Infantile vulva:
Rosebud vulva
Accompanied by infantile uterine horns and nonfunctional ovaries
Seen more in confinement gilts (higher in tethered gilts)
Seen more in heavily muscled gilts
Some can be stimulated to develop by transport and boar exposure
PMSG helps some gilts
Should you treat?
Tipped vulva:
Sky-hooked vulva
Erectile tissue in vulva
Effect on future reproduction is unknown
May indicate other reproductive abnormalities
Boars have difficulty breeding these gilts
Shouldn't be kept for breeding stock
Vulva injuries:
Fighting Parturition
Usually no effect on reproduction
Atresia ani:
Imperforate anus
Females have a rectovaginal fistula anterior to the vulva
Males die in 1-4 weeks
Two pair of dominant genes or viral infections
Red swollen vulvas:
Appear like a sow in heat
Mammary development
Exogenous estrogenic substances
Faulty underline (teats):
Blind teats, pin teats, and inverted nipples
Lack of sufficient teats:
7 per side
Abrasive concrete can cause underline problems
Poor teat spacing
3 teats on each side anterior to umbilicus
Evenly spaced
Straight line
Replacement selection

Reproductive tract deformities:
5-10% of all gilts have abnormal reproductive tracts
Slaughter checks are required for diagnosing the problems:
Hydrosalpinx or pyosalpinx:
Clear fluid or purulent material in oviducts
Occlusion or distention of oviducts
Abnormal embryonic development
Irregular or absence of estrus
Blind uterine horn:
Unilateral Normal cycle
Can get pregnant in unaffected horn but small litter results
Pregnancy depends on the size of the blind horn
Unilateral missing horn:
Infrequent Normal cycle
Small litter
Blind, double, or missing cervix:
Infrequent Normal cycle
Blind or missing cervix can't get pregnant
Double cervix can get pregnant
Common Seen more in confinement gilts
Ass. with rosebud vulva Absence of estrus
30% of the size of a normal cycling reproductive tract
Hypoplastic nonfunctional ovaries
Whole tract can be affected (oviduct and bursa most common)
Intraperitoneal injections??
Signs depend on the severity
Intersexuality (hermaphrodites):
.5% of the total population
More prevalent in Yorkshire (genetic?)
Genetic females usually:
True hermaphrodite Autosomal recessive
Ovarian and testicular tissue separately or together (internal or external)
Male pseudohermaphrodite:
Phenotype female External and internal female
Testes instead of ovaries Male behavior
Study pedigree to remove carriers

Cystic ovaries:
Large cystic follicles or corpora luteum
Irregular cycling (longer heat periods than normal)
Enlarged clitoris in some sows
Mainly secrete progesterone
Partial or complete failure of ovulation
Mycotoxins or exogenous steroids
Diagnosis difficult on live animal
Slaughter checks
Treatment usually ineffective
Physical exam
Herd history
Breeding records
Slaughter checks
Limited usefulness
Select better females
Don't create more problems

Locomotor causes of reproductive failure:
High culling rate
High preweaning mortality
Leg weakness:
Cause unknown
Rapid growth rate, good feed efficiency, and restricted exercise
Conformation (abnormal angulation of joints)
Foot rot:
Abrasions and cracked hoof walls
Downer sow in mid to late lactation
Fractures of the femur or vertebra
If they can't walk, they can't breed and reproduce.


Not a disease
Group of clinical signs
S = Stillborn
M = Mummies
ED = Embryonic Death
I = Infertility


Syndrome I:
Fatal infection of embryo or fetus
Dam is clinically normal (subclinical infection)
Abortion rare
Resorption of embryo or mummification of fetus
Earlier in gestation, fetus more susceptible
Porcine parvovirus, porcine enterovirus, Japanese B encephalitis virus
Occasionally hog cholera virus and pseudorabies virus
Problem not recognized until long after fetal death
Except for parvovirus, viruses inactivated by mummification
Syndrome II:
Maternal illness with or without disease of fetus
Abortion especially if in late gestation
Pseudorabies, hog cholera, and swine influenza
Viruses isolated from aborted fetus and newborn

Porcine Parvovirus
Nearly 100% morbidity in older breeding stock
Worldwide distribution
Extremely resistant virus
Can be transmitted by copulation
Boar fertility not affected
Transplacental infection during first half of gestation
Sow (No clinical signs)
Fetus immunocompetent in the last half of gestation
Virus isolated from mummies (FA of fetal tissue best)
Vaccine available

Porcine Enterovirus
9 serotypes
Worldwide distribution
Can be transmitted by copulation
Subclinical in sow and decreased semen quality
Developmental abnormalities reported (not common)
Isolated from tissues of affected pigs
No vaccination

Japanese B Encephalitis Virus
Not in U.S.A.
Asia primarily
Mosquito transmission
No effect on boar
Not transmitted by copulation
Developmental abnormalities common (hydrocephalus)
Affects fetus late in gestation:
Weak live pigs with nonsuppurative encephalitis
Virus isolation and culture for diagnosis
Vaccination, vector control, and controlled breeding

Pseudorabies Virus
Worldwide distribution
Severe maternal disease
Subclinical maternal and death to fetus
Virus isolation from sow, fetus, or stillborn
Vaccination and isolation of susceptible animals

Swine Influenza Virus
Prevalent in U.S.A.
20% of swine have antibodies
Disruption of fetal nutrition during maternal respiratory disease
Virus isolation from sow and fetus
Vaccine available

Hog Cholera Virus
U.S.A. is free!!
Embryonic resorption, mummies, fetal abnormalities, stillborn, and weak pigs
FA for diagnosis

Porcine Reproductive and Respiratory Syndrome
Lelystad virus (family Togaviridae)
Affects pregnant females, unweaned and recently weaned pigs, and growing and finishing pigs
Stillborn, abortion, mummies, autolyzed fetuses, and small litters
Interstitial pneumonia and bronchopneumonia
FA on fresh lung tissue and virus isolation for diagnosis
Vaccines available (MLV or killed)


Primarily a reproductive disease in swine
Mild signs in adults
L. canicola
L. grippotyphosa
L. icterohaemorrhagiae
L. pomona
L. bratislava
Shed primarily in urine
Venereal transmission possible but not common
Contaminated surface water the common source of infection
Abortion occurs 1-3 weeks after fetal infection
Infections late in gestation cause stillborn and weak pigs
Vaccination and decrease surface water contact

Orchitis and epididymitis in boars
Embryonic death and abortion
Can affect locomotor system (posterior paralysis)
Stillborn or weak pigs
No treatment
Validated free herd


Vaginal prolapse:
Purse string suture
Urinary catheter

Rectal prolapse:
Replace and purse string suture
Submucosal resection and purse string suture
Rectal rings

Uterine prolapse:
Some can be replaced vaginally (Very few)
Abdominal incision and pull uterus back into abdomen
Emergency slaughter

Hematoma of vulva:
Do nothing on a small hematoma
If it ruptures, ligate arteries
Horizontal mattress suture at the base of the vulva

Lateroflexion of the bladder:
Older gravid sow usually
Bladder reflects between pelvis and vaginal wall
Catheterize the bladder
Use Foley balloon catheter and tape it in place

Prognosis depends on how long sow has been in labor (over 6 hrs decreased prognosis)
Either flank, ventral midline, or lateral & parallel to mammary gland approaches.
Routine surgical procedure.

Typical reproductive organs and accessory glands:
Testicles Seminal vesicles
Epididymis Cowper's gland (bulbourethral gland)
Vas deferens Prostate
Tip of penis with a left corkscrew twist

Presperm fraction:
High bacterial contamination
Secretions of accessory sex glands
Very few sperm
Sperm rich fraction:
Largest concentration of sperm
Largest volume
Postsperm fraction:
Mainly gelatinous material
Few sperm
Strained out for AI use

Semen volume and concentration:
250 ml (150-500)
100 million sperm per milliliter (25-300)
Depends on size, age, and frequency of usage
To increase semen production, house boars separately
Daily collection gives more total semen and sperm production

Semen volume:
Testes and epididymis 2.5% of total
Prostate and urethral glands 55-75% of total
Seminal vesicles 15-20% of total
Bulbourethral gland 10-25% of total
Removal of accessory gland has no effect on other glands, ejaculation or libido
Removal of seminal vesicles and bulbourethral gland
No effect on fertility
Decrease the number of abnormal sperm
Increase the duration of sperm motility

Gradual process beginning at 4 months of age
6-8 months
Feed restriction:
Decreases growth rate
Delays puberty

Size at 1 year old
Kept until 5-6 years of age
Culled for reasons other than fertility:
Bad attitude

Number of boars required:
Pen breeding 1 boar per 8-10 sows for continuous farrowing
1 boar per 5 sows for all in - all out farrowing
6 1/2 months of age 1-2 services per week
8-10 months of age 5 services per week
10-12 months of age 2 services per day
8 services per week
Mature boar 3 services per day
12 services per week

Castrated boar = barrow

High temperature can result in 2 month infertility
Cold temperatures do not decrease reproductive function

Can't identify and estrus sow by smell
Depends on the behavioral reactions of sow
If it stands still, breed it
Must chase, sniff and nudge every sow in pen
Preputial washings and submaxillary salivary glands
Important for successful stimulation of sow
Aerosol spray commercially available
Reduces weaning to estrus interval
Makes boar meat smell
Courting song:
Chant de cour
Stimulates sow
3-20 minute ejaculation time
Severe fighting among unfamiliar boars: (death and/or injury)
Dominant boar breeds most often
Shy breeders may need sow brought to them
Boars raised in all male groups form stable homosexual pairs

Semen storage and AI:
AI not used extensively in U.S.A.
Problems with AI:
Heat detection
Poor survival of fresh sperm beyond 3 days (viability 4-5 days)
Semen storage:
At 5-8 C for 30 hours doesn't affect fertility
Looses motility and settles out on short-term storage
Reactivated by warming and shaking at 37 degree C
Artificial insemination:
50 ml total semen volume
3 billion sperm needed
Assuming 60% motility, 5 billion sperm in 50 ml fluid Diluents (extenders):
None promote sperm viability beyond a few days
Sodium sulfate and potassium sulfate
Calcium chloride and peptone
Egg yolk-phosphate mixture
Glucose tartrate and tartonic acid
Milk and cream
Citrate and phosphate extenders used for bull semen is toxic to boar sperm
Causes loss of motility and fertility
Techniques have been developed

Fertile boar:
Normal libido
Ability to mount sow
Ability to protrude penis and penetrate vagina and cervix
Ability to fertilize ova

Serological tests:
Previous diseases
How long on current premises:
Time in isolation (30 days minimum)
Exposure to prospective breeding herd (30 days minimum)
Frequency of use:
Time of last usage
Number of services per week
Conformation and body condition
Locomotor function:
Ability to move
Ease of movement
Front and rear legs
Stifles, shoulders, knees, hocks, fetlocks, and pasterns
Top line (back)
Size of tusks
High ambient temperature
Ability to mate

Genital exam:
All external parts present and accounted for
Large (10-15 cm long and 6-7 cm wide in mature boar)
Functional penis:
Incomplete erection
Hypospadias (urethra opens ventrally)
Persistent frenulum
Balling of penis in preputial diverticulum
Semen evaluation

Gloved hand:
Ability to mount and enter vagina
Sow in estrus
Glove on hand
Boar mounts sow
Gently grasp penis
Ejaculate collected in a prewarmed thermos (37 C) covered with a layer of coarse gauze to filter out gel fraction
Artificial vagina:
Not practical because of equipment, sanitization, and cost
No improvement over gloved hand method

Primarily sperm-rich fraction collected
Used in specialized cases:
Lame or injured boar No sow in heat
Old boar Shy boar
Bad attitude
No anesthesia: (injury to boar and/or handlers)
Ultra-short-acting barbiturates:
Surital at 4.4 mg/kg for first 180 kg then 2.4 mg/kg
8 mg/kg maximum dose
1 gram/ 350 pounds (140 kg)
Light plane of anesthesia
Face mask
Porcine stress syndrome
Xylazine (1 mg/#) plus ketamine (1 mg/#) IV
Remove feces from rectum
Insert probe approximately 25 cm into rectum
Express preputial diverticulum
Clip hairs around prepuce
Manual exposure of penis:
Light electrical stimulation
Push sheath caudally
Grasp glans penis
Atraumatic forceps to grasp the tip of penis:
Bozeman uterine dressing forceps
Rubber padded sponge forceps
Simulate for 5-7 seconds and rest for 5-10 seconds
Semen collected in prewarmed container
Collection from boars unable or unwilling to mate
Testicles and penis easily examined
Libido and mating ability not examined
Possible anesthetic accidents
Small volume


Age of Boar
8 - 12 over 12 Interference
months months Levels

Volume 100-300 ml 100-500ml

Color opalescent to milky watery to pink

Concentration 50-200 250-500 <50
(sperm / ml) X 106 X 106 X 106
Total sperm 15-30 30-50 <15
X 109 X 109 X 109

Motility >85% >85% <60
Wave motion (0-4) 2-3 2-3
Progressive motility >70% >70%

Primary abnormalities <10% <15%
abnormal heads <5% <5% >10%
proximal droplets <10% <10% >20%
abnormal acrosomes <5% <5% >10%
abnormal midpieces <5% <5% >10%
Secondary abnormalities <10% <15%
detached heads <5% <5% >10%
Normal sperm >85% >85% <75%

Free of blood, pus, and
foreign material + +

Equipment control:
37 degree C temperature
No pH change
No disinfectants
No sunlight
Clean, dry, and warm

Check motility as soon as possible:
Wave motion rated 0-4:
0 = absence of wave motion
1 = absence of wave motion but individual sperm motility
2-3 in normal fertile boars
Progressive motility:
Dilute with isotonic saline or buffered 2.9% sodium citrate
Cover with a coverslip
Evaluate for linear motility

Volume: Only the gel-free volume measured (Varies according to collection method)

RBC unipettes (1:200 dilution) and a hemocytometer
Coulter counter

Total sperm = sperm / ml X volume

Stained slides (5% nigrosin-eosin or new methylene blue)
View 100 cells (200 is better)
Primary abnormalities
All head and midpiece defects Double midpieces
Small, enlarged, double, and misshapen heads Proximal droplets
Acrosomal defects Double tails
Enlarged midpieces Tightly curled tails
Secondary abnormalities:
Distal protoplasmic droplets and bent tails:
May not be significant
Don't appear to affect fertility
Commonly observed in rested and older boars
Detached heads
Abaxial midpiece attachments considered normal in the boar
Occasionally normal appearing semen may not cause conception:
Be careful
Young boars (20-50% unacceptable breeders the first year)

Infertile boar = sausage
Very few sterile boars, many may be marginally fertile
Usually treatment should not be recommended

contributed by Bruce E Eilts on 11-Aug-98 at 04:20 PM

Swine Index


contributed by Bruce E Eilts on 25 September 2012


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