Overview and Clinical Importance
Porcine medicine is a critical component of the BCSE examination, with Domain 4 (Medicine) representing 50-55 questions, making it the LARGEST domain on the exam. Swine diseases have significant economic impact on the global pork industry and include several reportable/foreign animal diseases. This guide covers the major viral, bacterial, and multifactorial diseases affecting swine, with emphasis on etiology, clinical presentation, diagnosis, treatment, and prevention.
High-YieldThe BCSE tests practical clinical knowledge. Focus on differentiating diseases with similar presentations, understanding pathophysiology, and knowing key diagnostic tests and treatments.
| Feature |
Details |
| Etiology |
PRRSV (Arterivirus family). Two species: PRRSV-1 (European) and PRRSV-2 (North American). High mutation rate. |
| Target Cells |
Pulmonary alveolar macrophages and intravascular macrophages. CD163 receptor is essential for infection. |
| Transmission |
Direct contact, aerosol (up to 9.1 km documented), contaminated semen (shed up to 93 days), fomites, and needles. |
| Reproductive Signs |
Late-term abortions (last trimester), premature farrowing, stillbirths, mummified fetuses, weak-born piglets, increased preweaning mortality. |
| Respiratory Signs |
Interstitial pneumonia in nursery/finishing pigs. Decreased daily weight gain by up to 85%. Mortality 10-80% when complicated by secondary infections. |
| Diagnosis |
ELISA (detects antibodies to nucleocapsid protein - cannot predict immunity or carrier status), PCR assay (detects viral RNA), virus isolation. |
| Treatment |
No specific antiviral. Supportive care and control of secondary bacterial infections. Antimicrobials for opportunistic pathogens. |
| Prevention |
Modified live virus (MLV) vaccines (do not prevent infection but reduce viremia, lesions, clinical signs). Herd closure. Gilt acclimatization. |
| Disease Form |
Clinical Features |
| PCV2-SD (Systemic Disease) |
Formerly PMWS. Wasting, poor growth, enlarged lymph nodes, pallor, jaundice, diarrhea. Affects post-weaning pigs (5-12 weeks). Mortality can reach 10-30%. |
| PCV2-SI (Subclinical Infection) |
Most common form. Decreased average daily weight gain without overt clinical signs. Major economic impact. |
| PCV2-RD (Reproductive Disease) |
Late-term abortions, stillbirths, mummified fetuses. Virus in fetal hearts is diagnostic. |
| PDNS (Porcine Dermatitis and Nephropathy Syndrome) |
Red-purple macules/papules on skin (ears, hindquarters, abdomen). Enlarged kidneys with petechial hemorrhages. Type III hypersensitivity. |
| PCV2-LD (Lung Disease)/PRDC |
Component of Porcine Respiratory Disease Complex. Interstitial pneumonia. Often co-infected with PRRSV, SIV, Mycoplasma. |
Major Viral Diseases of Swine
Porcine Reproductive and Respiratory Syndrome (PRRS)
PRRS is one of the most economically significant diseases in the global swine industry, costing an estimated $664 million annually in the United States alone. It causes both reproductive failure in breeding animals and respiratory disease in growing pigs.
MEMORY AID - PRRS Features: Think 'PRRS = Pregnancy Problems + Respiratory Ruin in Swine' - The two main manifestations are reproductive failure and respiratory disease.