KuneKune Reproductive Anatomy & Breeder Failures
By AKKPS Member Debra Allen of Allen's Acres
To be a responsible breeder of KuneKunes, one must understand basic facts of the reproductive process in pigs. Far too often, breeding occurs and owners scramble at the last minute to understand the process and sometimes make mistakes that result in poor outcomes for the piglets or the sow. This article will start with basic reproductive anatomy and then go into reproductive failure.
SOW ANATOMY
The primary structures of the female reproductive tract are the ovaries, they have two major functions:
(1) to produce ova, the female germ cells and
(2) to produce the hormones progesterone and estrogen.
Each ovary is surrounded by a thin membrane called the infundibulum which acts as a funnel to collect ova and divert them to the oviduct. The oviduct is about 6-10 inches long and acts as the site of fertilization.
There are two uterine horns. Each is 2-3 feet in length in the non-pregnant sow. They act as a passageway for sperm to reach the oviduct and are the site of fetal development. The uterine body, which is small compared to some other species, is located at the junction of the two uterine horns.
The cervix is a muscular junction between the vagina and uteri. It is the site of semen deposition during natural mating and AI. It is dilated during heat (estrus) but constricted during the remainder of the estrous cycle and during pregnancy.
The vagina extends from the cervix to the vulva and serves as a passageway for urine and the piglets at birth. The bladder is connected to the vagina by the urethra.
The vulva is the external portion of the reproductive tract. It often becomes red and swollen just prior to estrus and this swollen condition is usually more pronounced in gilts than in sows.
The hypothalamus located at the base of the brain secretes gonadotropin releasing hormone (GnRH) which regulates the anterior pituitary to secret FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) into the blood which stimulates the production of the ovarian hormones, estrogen and progesterone, which in turn regulate the reproductive process. Oxytocin is released from the posterior pituitary gland.
The important thing to grasp here is that a KuneKune may expel several placentas. Sows may deliver piglets from one horn and then a placenta, take a rest, then deliver the other horn and one or two placentas. They will also deliver from both horns simultaneously, one from each in turn, and then deliver multiple placentas at the end. You should try to preserve the placenta(s) and lay it out on a relatively clean flat surface to check that it’s intact. You should see strings that were the ends of the umbilical cords for each piglet. The purpose of verifying completeness of a placenta is to make sure no obvious pieces are missing. If pieces remain inside the sow, it can lead to infection later on, causing severe risk to the sow. Retained placentas must be treated by a veterinarian.
INFERTILITY OF THE SOW
There are some diseases that have a direct negative impact on fertility, such as leptospirosis, porcine reproductive and respiratory syndrome (PRRS) and parvovirus, but other conditions, such as flu, can also be detrimental. A sow with a fever will struggle to conceive while her body tries to fight infection. Periodic health screening and comprehensive tailored vaccination programs ensure the breeding herd can perform to its potential.
Pyometra, a non-infectious uterine infection, will also prevent the animal from conceiving. Possible causes of pyometra include damage to the cervix and soft tissue during farrowing, inappropriate body condition, and low vitamin E and selenium levels.
Polycystic ovaries occur in about 10% of anoestrus cases (where pigs don’t exhibit heat). It is not clear what causes polycystic ovaries, but stress leading to high cortisol levels and hormone treatment misuse are thought to be causative. Early weaning could also be a contributing factor.
Post-mortem examinations at slaughter can point towards some of these non-infectious causes. The ovaries can be examined for size and structure, and the uterus for any signs of infection.
The body condition of gilts/sows at breeding and conception is very important. The most common cause of anoestrus sows is poor body condition following weaning. Obesity is also an issue in some kunekunes. Fat deposits around the ovaries and may prevent proper ovulation.
The presence of mycotoxins, principally zearalenone, within the diet should always be considered when investigating causes of poor fertility.
Temperature also has an influence – extremes of temperature, both hot and cold, will have a negative effect on performance. Heat, in particular, makes sows more lethargic, but wallows and shade can combat this.
When an animal is stressed, the stress hormone cortisol is released.
This triggers the “fight or flight” response which stimulates a degree of self-preservation, where resources are directed away from reproduction. High cortisol levels may also give rise to polycystic ovaries. Reducing stress throughout the weaning, service, and early gestation periods will improve rates of conception.
BOAR ANATOMY
The male reproductive system consists of two testicles, each of which is held almost vertically with the tail of the epididymis at the top.
The epididymis is the area within which all the mature sperm is stored and held until ejaculation. From each testicle a tube, the urethra, carries the sperm into the abdomen via the inguinal canal. (If this hole is enlarged an inguinal rupture will be seen).
From there it enters the neck of the bladder and continues in the groin down the penis to the exterior as the urethra. Thus from the neck of the bladder to the tip of the penis the urethra can carry either sperm or urine.
There are three glands called the seminal vesicles, the prostrate and the bulbo urethral glands. The seminal vesicles produce the bulk of the ejaculate (300ml) and fructose to nourish the sperm. The prostrate gland provides other nutrients and the bulbo-urethral gland the jelly that you often see at the end of mating
During service/mating, the sperm in the epididymis are pulsated down the urethra to be joined by the seminal fluids. This is a continuous process during the period of mating. You can see it if you stand behind the boar and you should check it when you supervise services.
The penis, which is long and rigid has a sigmoid or S - shape in its top half and an anti clockwise spiral at the end. It is 300-500mm long.
The preputial sack is filled with very smelly fluids including pheromones and it also has a very high bacterial content. The bacteria are potential pathogens and emptying the sac by squeezing at service increases the risk of infection entering the womb, particularly towards the end of the heat period.
Sperm is produced and matured under the influence of luteinising hormones (LH) and follicle stimulating hormones (FSH) and the whole process is controlled by the pituitary gland which is at the base of the brain
INFERTILITY OF THE BOAR
Infertility in the boar can be caused by a number of factors. These can include failure of sperm production, production of abnormal sperm, overuse of the boar, physical abnormalities of the male genital tract which prevent delivery of semen at mating, physical or psychological factors which prevent mating and, finally, infection which destroys the products of conception.
The production of normal sperm can be affected by genetic factors, age (boars are not fertile until at least 5 months of age and semen quality declines in old animals), high body temperature (fever can cause poor semen quality and even aspermia), high environmental temperatures and infection of the testes and accessory sex glands.
Those with ruptured penises also cannot mate. Boars may be reluctant to mate if ill, or if lame and some boars will not mate for psychological reasons. This is particularly common in young boars.
Obesity in boars can prevent breeding simply because of inability of the boar to mount or get close enough to penetrate. Finally, infection with agents such as PRRS,Leptospirosis, Brucella Suis and contamination from fecal or preputial organisms can cause death of the products of conception.
REPRODUCTIVE FAILURE IN SOWS
Abortion is the most dramatic expression of pregnancy loss. When the incidence increases for a given herd, an infectious agent is usually suspected. This increase may follow the addition of animals or the mingling of previously isolated groups of animals. Approximately 38 percent of diagnosed abortions are attributed to infectious causes. The stage of gestation during which the sow and/or fetuses become infected will determine the litter's ability to survive. In some cases the infectious agent will directly affect developing fetuses and placentas, causing fetal compromise and death.
Any severe illness in a pregnant sow may result in fetal death due to a disruption in the normal uterine environment. One, several or all fetuses in a litter may be lost. If fetal death occurs at less than 35 days of gestation, fetuses may be reabsorbed. If infection occurs between 35 and 70 days of gestation, fetal mummification occurs. If infection occurs after 70 days of gestation, pigs may be delivered weak or dead.
Bacterial infections
Bacteria gain access to the uterus through the open cervix at farrowing, but usually are eliminated before they are able to establish an infection. Sows will have a vaginal discharge for 1 to 3 days after farrowing. This discharge is normal, is not foul smelling and is not associated with clinical illness in the sow or pigs.
However, if a sow farrows in an environment contaminated with excessive fecal material or the delivery is assisted in an unsanitary fashion, metritis may develop. This is the most severe form of infection in the uterus. The uterus fills with large amounts of smelly fluid and decomposing tissue. The sow will develop a fever, be ill and possibly die as a result of bacterial toxins. Her pigs may demonstrate signs of weakness due to malnourishment. This condition is seen within days of farrowing. If the sow recovers, her fertility during the next breeding will be reduced.
Endometritis or inflammation of the lining of the uterus is less severe clinically, but possibly more important economically. Bacterial infections of the reproductive tract may result in conception failure and/or early embryonic deaths. Bacteria gain entrance to the uterus during estrus and breeding because the cervix relaxes at this time. An increased return-to-service rate may be the only indication that a problem exists. Return intervals may be normal or prolonged.
Inflammation of the endometrium is not compatible with the survival of embryos and the pregnancy will be terminated. These animals are often clinically normal or they may have a low-grade fever. A mild vaginal discharge may be seen around the time of the next expected heat. Gilts that are housed in overcrowded conditions may also develop endometritis.
Vaginitis will also cause a vaginal discharge. Fertility may not be reduced unless bacteria gain entrance to the uterus at breeding. Gilts and sows that have been exposed to high levels of the mycotoxin zearalenone in the diet will develop vaginitis and a discharge. The estrogenic properties of this compound will prevent these animals from cycling normally.
Note: A diet high in calcium or phosphorus may result in the formation of salts in the urine leading to a white, chalky fluid which is seen at the vulva. This should not be confused with infection, although infections of the urinary tract may cause vaginal discharges.
Adequate water intake helps to prevent infection by encouraging frequent urination and mechanical flushing of the urinary tract.
The bacteria that cause these urinary and reproductive tract infections can be found within the tracts and/or in the environment. When the tracts are contaminated and the defense mechanisms are overloaded, infection results. The most effective means of preventing this is to provide a clean environment (proper waste removal) and a sufficient source of fresh water.
Leptospirosis
A large number of Leptospira organisms are known to infect swine. In most herds that have already been exposed, few clinical cases of disease will be found.
Leptospira bacteria prefer the kidney and are shed in the urine. Contact with contaminated urine is the most common means of spreading the infection to other animals. Leptospira also will localize in the pregnant uterus. If susceptible breeding animals become infected, leptospirosis may lead to abortions, stillbirths or the birth of weak piglets.
Several forms of Leptospira interrogans have been found to infect swine. Pomona is most commonly seen in swine infertility. Bratislava also has been found to persist in the oviducts and uterus of non-pregnant females and in the upper genital tract of boars contributing to infertility. It is possible that this infection could be spread during mating. Vaccines are available for leptospirosis. However, the immunity they provide is usually short-lived. Breeding animals should be vaccinated at least twice a year and up to four times a year in infected herds. Vaccinations should be given prior to breeding. Antibiotics will help reduce the incidence of disease but cannot completely eliminate it from an infected herd. Rodents and local wildlife (squirrels, opossum, raccoon, rabbits and even cows) may also be infected and contribute to the spread of leptospirosis. Management practices that eliminate the rodent population and prevent urine contamination of feed and water will contribute a great deal to controlling infection. During an outbreak, clinically ill animals should be treated and in-contact animals should be vaccinated.
Brucellosis
Brucellosis in swine is caused by Brucella suis. Brucella organisms are also infectious to humans, but due to federal eradication programs very few cases are reported in people or livestock. Brucellosis is spread by direct contact with infected tissues, primarily aborted fetuses and membranes. Boars can develop a persistent infection and shed bacteria in the semen, which contributes to the spread of this disease. Females that become infected at breeding may abort at any stage of gestation. Antibiotics are of little value in treating brucellosis. The prevalence of swine brucellosis has been reduced to the point that vaccination is not practical. Management practices for maintaining a brucellosis-free herd status are encouraged. The human health risks of brucellosis should always be considered when handling any aborted fetuses or fetal membranes.
Porcine parvovirus
Few animals exhibit clinical illness as a result of porcine parvovirus (PPV) infection. This virus is found in most swine herds, but previously exposed animals develop immunity. Porcine parvovirus will cross the placenta and infect developing fetuses. Non-immune females that become infected during the first half of gestation will usually have several mummified fetuses at farrowing. Gilts are affected much more often than sows.
Infertility, stillbirths, neonatal deaths and delivery of weak pigs may follow infection during pregnancy. Abortions resulting from PPV infection are uncommon. If infection occurs late in gestation, fetuses usually will survive. Because PPV is widespread in swine herds, all gilts should be naturally exposed or vaccinated at least 30 days prior to breeding. Inactivated as well as modified live vaccines are available and should be administered under the direction of a licensed veterinarian. There is no treatment for PPV-induced infertility, but animals that are naturally infected are often immune for life.
Other diseases
Pseudorabies, PRRS, Porcine Enteroviruses, SIRS can all also result in abortions, mummies, or infertility. See below:
Mixed bacterial infections
Clinical signs
Increased return-to-service. Mild to profuse vaginal discharges. Sows with metritis will have a fever and go off feed.
Preventive measures
Do not house gilts or sows in overcrowded, unsanitary conditions. Provide ample amounts of fresh water.
Comments
A discharge for one to three days after farrowing is normal.
Leptospirosis interrogans pomona
Clinical signs
Few clinical cases in previously exposed herd. Susceptible breeding females may abort or deliver weak or dead pigs.
Preventive measures
Vaccinate breeding animals two to four times each year. Protect feed and water from urine contamination.
Comments
Rodent numbers should be controlled because they also contribute to the spread of this disease.
Brucella suis Clinical signs
Abortions during any stage of pregnancy.
Preventive measures
Prompt removal of all aborted tissues. Routine testing for maintenance of brucellosis-free herd.
Comments
Potential for human infection.
Porcine parvovirus
Clinical signs
Delivery of mummified pigs. Stillbirths, neonatal deaths and infertility are possible. Abortions are rare.
Preventive measures
Vaccinate or expose gilts to infection 30 days prior to breeding.
Comments
Previously infected animals develop a life-long immunity.
Porcine enteroviruses
Clinical signs
Resembles porcine parvovirus. Abortions are rare.
Preventive measures
Expose gilts to fecal material from older sows prior to breeding.
Comments
No vaccine is available.
Pseudorabies virus
Clinical signs
Abortions may follow fever and respiratory disease in susceptible gilts and sows. Live-born pigs are weak. Pneumonia in growing pigs.
Preventive measures
Vaccination will reduce the severity of clinical disease. Participation in the federal eradication program.
Comments
Vaccination requires the approval of the state veterinarian.
PRRS/SIRS virus
Clinical signs
New herds experience an increase in abortions, stillbirths and mummies. Pneumonia in pigs of all ages. Reduced fertility in recovered sows.
Preventive measures
New animals should be purchased from unexposed herds and quarantined for at least 30 days.
Comments
No vaccine is available.
Abnormal vaginal discharges must be distinguished from normal postpartum discharges and urinary sediments in order for affected animals to be properly managed. Discharges resulting from reproductive tract infections generally are associated with other reproductive events such as farrowing (metritis) and estrus or breeding (endometritis). Discharges associated with vaginitis and urinary tract infections usually do not follow the reproductive cycle. Milder cases can be treated with antibiotics, but persistently infected animals should be culled.
Porcine parvovirus or enterovirus should be suspected when the incidence of mummified fetuses increases, particularly in gilts not previously exposed. Respiratory distress accompanied by high fever and followed by abortions may indicate a pseudorabies or PRRS infection in a susceptible herd. Abortions resulting from brucellosis are uncommon but leptospirosis should be considered in areas where it is prevalent. Vaccines are available for PPV, PRV and leptospirosis. These should be administered at least 30 days prior to breeding gilts and repeated as necessary in high-risk areas (leptospirosis).
MORE ARTICLES
There are several good informational resources at the AKKPS website about other reproductive topics:
Fundamentals of Farrowing (click here)