Reproductive Abnormalities in Pigs (Sows and Gilts)

Reproductive abnormalities in pigs (sows and gilts) is examined by physical and internal examinations like structural soundness, examination of genitalia, etc.

Physical Examination

Careful physical examination is required for detection of reproductive abnormalities in pigs (sows and gilts):

• Selecting potentially fertile breeding animals.
• Culling gilts with structural or genital abnormalities prior to breeding.
• Along with a herd history helpful in the diagnosis of reproductive failure in individual animals or in breeding groups within a herd.

When indicated, internal reproductive organs should be recovered from slaughtered animals for a thorough examination as useful information can be obtained when other procedures fail.

Structural Soundness

Soundness in replacement gilts is especially significant, since most structural faults and weaknesses are aggravated with age and confinement rearing.

Special attention should be given to selecting gilts free from foot, leg and joint problems, which may impair their future reproductively.

A moderate slope to the pasterns provides the animal with a cushion to the foot and leg joints, enabling her to cope with solid surfaces in confinement. Gilts and sows with hoof cracks, sole bruises or other foot problems should be culled because attempted treatments are often unsuccessful. Such problems may arise from abrasive or damp, slick flooring.

Too much slope in the rump area tends to make the animal more prone to unsoundness as she matures. A steep rump also displaces the vulva to a low position and angle so that boars often experience difficulties in entering the sow during mating.

Extreme muscling leads to delayed puberty, low conception rate, farrowing difficulty and poor mothering ability.

Examination of External Genitalia

Observing the vulva of replacement gilts at 5 ½ to 6 months of age can help detect potentially sterile or slow-breeding females.

The most commonly observed abnormality is the:

• infantile vulva which is usually accompanied by small, prepubertal ovaries and uterine horns.
• dorsally “tipped vulva”. Boars may experience difficulty in servicing gilts having this trait.
• Injures of the vulva may occur from fighting or at parturition. Unless they are severe, they generally do not contribute to future reproductive problems.
• Atresia ani, or imperforate anus, is a congenital defect observed in all breeds. In gilts the rectum and vagina may be joined, forming a recto vaginal fistula just anterior to the vulva. Males die because they are unable to defecate. Gilts defecate via the vulva opening.
• Occasionally, an unusually large percentage of females within a group is observed to have red, swollen vulvas, typical of females in estrus. This observation, when coupled with mammary development in non pregnant females and barrows, indicates the presence of exogenous estrogenic substances in the feed.

Examination of Mammary System

A sound underline with atleast six functional, well developed and evenly spaced teats on each side, with three in front of the navel is prefered.

Gilts with a blind teat that does not fully develop, a pin nipple or an inverted nipple should not be considered as replacement animals.

Internal Examination

In herds with a high incidence of reproductive failure that are not diagnosed by other methods, examination at slaughter is recommended.

Females should be tattooed prior to slaughter for identification so that the individual animal‘s reproductive history can be related to the observed reproductive tract disorder.

Observe for:

• the presence and size of follicles, corpora lutea and cysts in each ovary.
• any adhesions surrounding the ovaries or within the ovarian bursa.
• size of the uterine horns.

Externally, each oviduct and uterine horn to the vagina should be traced, for occlusions, missing parts or adhesions.

After gross examination the tract is opened and is examined and noted for the presence and characteristics of fluid or embryonic tissue.

Abnormalities (Anatomical Abnormalities)

Hydrosalpinx and Pyosalpinx

Hydrosalpinx and pyosalpinx refer to distention of oviduct with clear fluid and pus like material, respectively. Occur more frequently in gilts than in sows. It result from abnormal embryonic development and may be hereditary.

Affected females have regular estrous cycles but are prone to repeat breeding and reduced litter size. If lesions are bilateral, affected females are sterile.

Segmental Aplasia

Segmental aplasia may occur at any position along the uterine horn but most commonly occurs near the uterine body. Occasionally, an entire uterine horn may be absent.

Afflicted females will cycle normally. It is possible to have pregnancy in the patent side, but litter size is usually reduced.

Blind, Double and Missing Cervix

Blind, double and missing cervix abnormalities occur infrequently. Females with either condition cycle normally.

If part or the entire cervix is missing, the female is sterile. Pregnancy can be achieved in females with a double cervix.

Infantilism

Infantilism is a common abnormality and is generally but not always associated with confinement-reared gilts wherein the presence of a very small vulva and the absence of estrus are suggestive of this condition.

The infantile tract is approximately 30 per cent of the size of a tract from normally cycling gilt.

The ovaries are hypoplastic and nonfunctional with numerous small follicles and no corpora lutea. This condition is common in gilts with delayed pubertyor gilts less than 6 months of age.

Adhesions

Adhesions have been observed in all areas of the reproductive tract but more frequently in the oviduct and ovarian bursa.

Cyclic activity is normal. Reduced litter size and infertility are frequently noted.

Intersexuality

Intersexuality is more predominant in the Yorkshire breed in which a portion of the female reproductive tract has differentiated into its male homolog.

Intersexuality is mostly inherited, inheritance is thought to be autosomal recessive accompanied by modifier genes.

Intersexuality is characterised by presence of an ovotestis, which may be internal or external, whereas others may have a prominent clitoris and “sky hood” vulva. Some intersexes show male characteristics such as tusk development and mounting behavior.

Cystic Ovaries

Cystic ovaries originate in a complete or partial failure of ovulation. Therefore, cystic follicles may appear on the same ovary as normal appearing corpora lutea.

Cysts may vary in size from 12 to 50 mm. Affected females may be anestrus or exhibit near normal estrus cycle patterns.

Most attempts at treatment are ineffective for Cystic ovaries.