Special topics on swine diseases：Porcine Endemic Pneumonia

Special topics on swine diseases：Porcine Endemic Pneumonia

Overview:
Porcine Endemic Pneumonia is a chronic respiratory infectious disease in pigs. The causative agent is Mycoplasma hyopneumonia (also known as M. hyorhinis), and the primary clinical symptoms include coughing and dyspnea. The characteristic lesion is fusiform bronchopneumonia, with some lung lobules showing "meaty" consolidation. The infection mechanism involves Mycoplasma infecting the bronchial cilia, damaging them and causing a loss of the tracheal function to block pathogens. Secondary infections by other pathogens in the environment (e.g., Pasteurella, Actinobacillus pleuropneumonia, Salmonella, and viruses) lead to multi-factorial respiratory diseases. In acute cases, pulmonary edema and emphysema predominate; in subacute and chronic cases, "shrimp meat"-like consolidation of the lungs is observed. The disease has a high infection rate but low mortality, though it can cause growth retardation and reduce feed efficiency. In other words, it prolongs the time to market for pigs.

Diagnosis:
The clinical symptoms and pathological lesions are useful for diagnosis. The disease should be suspected when a large group of pigs shows paroxysmal dry cough, dyspnea, growth retardation or delay, and very low mortality. The pathological lesions show a clear boundary between diseased and normal lung tissue, and the lesions are mostly confined to the apical, cardiac, middle, and anterior lower parts of the diaphragm lobes, with a firm, pancreas-like consistency.

Epidemiology:
There are no breed, age, or sex differences in the disease occurrence, and it can occur year-round. It is more common during cold, rainy, humid, or rapidly changing weather. Poor feed quality, overcrowding, damp, and poorly ventilated pigsties are major risk factors. The mortality rate is not high with solo infection, but once the disease enters a pig herd, it is difficult to eradicate without strict measures.
In natural infections, Pasteurella, Streptococcus, Actinobacillus pleuropneumonia, Salmonella, various pyogenic bacteria, Mycoplasma hyosynoviae, and Chlamydia can cause secondary infections, leading to exacerbation of the disease and increased mortality.

Prevention and Control:

1. Self-breeding and Self-raising: Strictly prohibit the introduction of pigs with infectious diseases. If introduction is necessary, ensure strict quarantine (observation period should be at least two months) and proper disinfection management.

2. Nutritional Management: Ensure that pigs at all stages receive balanced nutrition and avoid feeding moldy or spoiled feed. Control the microenvironment according to seasonal changes, strictly manage stocking density, and regularly alternate disinfection with Roxycide and other chemical disinfectants.

3. Vaccination: Vaccines should be injected into the thoracic cavity; intramuscular injection is ineffective. Avoid feeding or injecting drugs such as Tetracycline or Kanamycin that suppress vaccine efficacy within 15 days before and 2 months after vaccination.

4. Mycoplasma Prevention: Since Mycoplasma hyopneumonia can change surface antigens to evade immunity, immunity can be weakened. Therefore, pig farms should combine medication treatment with vaccination, typically for a course of 3-5 days. Special care should be given to pregnant sows, who should be fed with medicated feed to cleanse the herd. Their piglets should be raised separately and not kept for breeding. If conditions allow, early isolation and weaning should be implemented to minimize contact between sows and piglets.

5. Drug Prevention and Cleansing:

Breeding Sows: Water-soluble Amoxicillin 250 µg + Mycoplasma Cleansing 100 µg + Tylosin 100 µg, mixed with feed 1 week before and 1 week after farrowing.

Piglets: Administer long-acting Tetracycline 0.2 ml/kg body weight at 3, 7, and 21 days after birth.

Nursery Pigs: Use compound Tiamulin (40 g per bag) mixed with 80 kg of feed for 15 days during the group transfer stage.

Replacement Pigs: Water-soluble Amoxicillin 250 µg + Mycoplasma Cleansing 100 µg + Tylosin 100 µg, administered once a month for one week.

Finishing Pigs: Preventive medication should be given for one week at 13 and 18 weeks of age.