Vaccinations are available for a number of diseases that affect swine. In some cases vaccination constitutes the major part of the control of the disease. In many other cases it is only a small part of the control program. Vaccination programs need to be tailored to each swine operation. Remember that vaccination only raises a pig's level of resistance. If other important management procedures are neglected, even this elevated level of resistance may be inadequate to prevent disease.
Vaccines must be stored and administered according to label directions if they are to be effective. Slaughter withdrawal time must be observed at all times to avoid illegal residues. The most common times for administering many vaccines are before breeding and before farrowing. This protects the sow and passes antibodies to the piglets for their protection.
Colibacillosis (scours or diarrhea in baby piglets caused by E. coli bacteria) is the leading killer of piglets. Enteric diseases occur in piglets as young as two to three hours. E. coli bacteria attach to the lining of the intestine, producing toxins and making it impossible for the body to absorb fluids or nutrients. The result is severe fluid loss resulting in death from rapid dehydration. In some cases death occurs before clinical signs are even seen.
Ileitis (proliferative enteropathy), associated withLawsonia intracellularis, is a common diarrheal disease of grow-finish pigs. It causes a sudden onset of diarrhea with inflammation of the ileum in the small intestine and the colon. Cases are often mild, but ileitis can cause persistent diarrhea with high mortality.
Clostridium perfringens Type C also causes a severe and sudden enteric disease called enterotoxemia. Death results from the release of potent toxins produced when the bacteria rapidly multiply in the intestine.
Clostridium perfringens Type A naturally resides in the swine intestine, but it remains one of the leading causes of diarrhea in neonatal pigs. Pathogenic C. perfringens Type A bacteria produce destructive exotoxins, which cause yellow-to-white pasty diarrhea – usually within the first week of life.
Salmonellosis in swine is caused mainly by two organisms: S. choleraesuis and S. typhimurium. These bacteria can cause severe sickness in the form of bloody diarrhea, pneumonia, or widely spread infections throughout the entire body.
Consistent, predictable reproductive performance is essential to a profitable swine operation. While swine producers can easily observe major problems in the herd – abortion storms or unusually poor conception rates – more common reproductive problems may be difficult to detect without accurate records. Delayed conception, repeat breeders, small reductions in pigs-born-live-per-litter and lighter pigs at weaning are often the only outward signs of disease.
Enteroviruses effects are primarily on intestinal tract, but infection during gestation also can cause abortion, stillbirth, and deformed piglets
Leptospirosis usually occurs as a subclinical infection with few if any outward signs. Leptospirosis is a contagious disease carried by many animals, including dogs, mice and rats. It is shed in the urine, which contaminates feed and water and spreads disease, and can also be transmitted to nursing piglets in the milk. Leptospirosis causes abortions late in gestation, stillbirths and birth of weak piglets.
PRRS (Porcine Reproductive and Respiratory Syndrome) is a viral disease with severe reproductive effects, including abortion storms, stillbirths and mummified fetuses, as well as respiratory-related symptoms. Sows and grower-finisher pigs suddenly become anorectic and have difficulty breathing. Sows begin aborting, followed by a dramatic increase in stillbirths. Death loss is high in pre-weaned and nursery pigs; those that are infected and survive are usually stunted and perform poorly.
Porcineparvovirus is thought to be responsible for the greatest portion of embryonic deaths, mummified fetuses, and stillborn pigs in the U.S. Gilts are especially vulnerable to parvovirus infection. Depending upon the stage of gestation in which infection occurs, reproductive effects include early embryonic death, reabsorption of fetus, mummified fetuses, sterility, stillbirths, strung-out farrowing intervals, and small litters.
Respiratory Diseases and Rhinitis
Mycoplasma hyopneumoniae is extremely common, especially in commingled groups of pigs and continuous flow systems. Disease is spread by direct contact from sows to piglets, and then among piglets once they are commingled. The disease has a slow onset with a long incubation, so symptoms may not show up until pigs are three to six months of age. Almost all mycoplasmal pneumonia infections are complicated by secondary pneumonias, which can result in high death losses. Severe disease is often due to a complex interaction between mycoplasma bacteria, a poor environment (including changes in weather), and secondary infections from other bacteria, viruses, and parasites.
Bordetella bronchisepticacausesAtrophic Rhinitis (AR). These bacteria can act as the primary invader, or may set the animal up for a secondary infection with bacteria such as Pasteurella multocida. Nasal passages damaged by AR are not able to do an effective job of filtering the air the pig breathes, allowing more bacteria access to the lungs. This, in turn, makes it more likely that the pig will develop severe pneumonia. B. bronchiseptica also causes bronchopneumonia, a more severe disease that can occur in piglets as young as three to five days.
Pasteurella multocida is another important cause of pneumonia. It has two primary types – Type A and Type D. Type A is a secondary invader that takes advantage of previous lung damage and causes severe pneumonia. Type D colonizes in the nasal passages and releases a toxin that damages tissues. It can cause atrophic rhinitis in older pigs.
Erysipelas is an infectious disease caused by a type of bacteria commonly found in swine operations. In the breeding herd, erysipelas can cause abortion and stillbirth, as well as overall poor reproductive performance including repeated breeding and weak piglets. The most common clinical sign is a rash like appearance on the skin and a high fever. Newborn or young piglets are very susceptible to the disease if the sow has not been vaccinated. The most susceptible group of swine, however, is recently weaned animals that are no longer receiving maternal antibodies through milk and colostrum.
Porcinecircovirus type 2 (PCV2) is considered by most to be the etiologic agent of postweaning multisystemic wasting syndrome (PMWS), but it is also found in association with numerous other conditions. These conditions include porcine dermatitis and nephropathy syndrome (PDNS), porcine respiratory disease complex (PRDC), congenital tremors (CT) type AII, reproductive failure, and enteritis. PCV2 is found in virtually all swine herds in the U.S. and Canada and causes varying degrees of illness depending on the herd and the genetics. The most common sign of PCV2 infection is a failure to thrive of upwards of 20% of the pigs in the finisher.
Vaccines are also available for several other diseases (i.e. Actinobacillus Pleuropneumoniae, Haemophils Parasuis, Pseudorabies, Streptococcus Suis, Rotavirus, Swine Influenza) but are generally used only if they have been diagnosed and vaccination is felt to be cost-effective.