Mycoplasma in Livestock Production: Focus on Pigs and Poultry

By DVM Miltos Ioannou

As discussed in our previous article on mycoplasma in livestock, this genus of bacteria poses a major challenge for animal health and farm profitability. Mycoplasma infections not only lead to direct clinical signs but also suppress the immune system, increasing vulnerability to other infectious agents. These issues are often worsened by suboptimal biosecurity and livestock management practices, such as overcrowding and poor housing conditions.

Mycoplasma Infections in Pigs

Mycoplasmal Pneumonia (Enzootic Pneumonia)

Mycoplasma hyopneumoniae is the causative agent of enzootic pneumonia in pigs. This respiratory disease is widespread and commonly occurs under poor environmental or husbandry conditions. When Mycoplasma hyopneumoniae co-infects with other pathogens, it becomes part of the broader Porcine Respiratory Disease Complex (PRDC).

Transmission and Risk Factors

The disease spreads primarily through:

• Nose-to-nose contact via nasal secretions from carrier pigs

• Aerosol transmission, particularly in poorly ventilated areas

• Environmental stressors, including dust, ammonia, and crowding

Carrier pigs may harbor the bacteria for months, posing long-term infection risks within herds.

Clinical Signs and Impact

Infected pigs exhibit:

• Chronic, dry, non-productive cough

• Reduced average daily weight gain and feed efficiency

• Pneumonia in cases with secondary bacterial infections

Morbidity is high, while mortality is generally low unless complications arise.

Prevention and Control

Vaccination remains a popular method to manage Mycoplasma hyopneumoniae:

• Typically administered before weaning and boosted 2–3 weeks later

• Shown to reduce lung lesions and improve growth performance

Antibiotics may be used for treatment or prevention, but outcomes vary. Optimal farm management, including biosecurity measures and environmental control, plays a critical role in disease prevention.

Other Mycoplasma Pathogens in Swine

Mycoplasma hyosynoviae

• Affects pigs between 10–24 weeks of age

• Clinical signs: arthritis, joint swelling, lameness, rough hair coat

• High morbidity (up to 50%), but low mortality

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Mycoplasma hyorhinis

• Affects piglets aged 3–10 weeks

• Causes polyserositis and arthritis

• Symptoms include labored breathing and difficulty moving due to swollen joints

Both infections are treated using tetracyclines, tiamulin, or lincomycin. As with M. hyopneumoniae, good hygiene, ventilation, and stress reduction are key.

Mycoplasmosis in Chickens

Mycoplasma gallisepticum (M. gallisepticum)

This pathogen causes chronic respiratory disease in broilers and egg production drops in layers and breeders. It often co-infects with other pathogens, exacerbating its impact on flock health.

Transmission

• Vertical: Through infected eggs from breeder stock

• Horizontal: Via aerosols, contaminated water or feed, wild birds, or farm equipment

The infection may remain dormant for months and re-emerge under stress.

Predisposing Factors

• Cold weather and poor air quality

• Overcrowding and concurrent infections

• Some live virus vaccinations that can enable infection

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Clinical Signs

• Respiratory distress: coughing, sneezing, nasal and ocular discharge

• Poor weight gain and feed conversion

• High morbidity, low mortality (unless complications occur)

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Management and Treatment

• Tylosin, tilmicosin, and tetracyclines help control clinical signs but do not eliminate infection

• Effective prevention includes sourcing stock from M. gallisepticum-free flocks and implementing strict biosecurity

Mycoplasma synoviae (M. synoviae)

M. synoviae affects broilers and layers, causing economic loss through slaughterhouse condemnations and egg shell abnormalities.

Transmission and Clinical Signs

• Transmitted both vertically (eggs) and horizontally (environment)

• Symptoms include:

  • Lameness, swollen joints, breast blisters

  • Depression and birds resting near feeders/waterers

  • In layers, egg production drops and shell deformities

Morbidity ranges from low to moderate, with mortality around 1–10%.

Control Measures

Prevention and treatment for M. synoviae are the same as for M. gallisepticum:

• Antibiotics (as above)

• Sourcing from pathogen-free flocks

• Maintaining strong biosecurity protocols

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Conclusion

Managing mycoplasma in pigs and poultry requires a strategic combination of vaccination, antibiotic use, and robust biosecurity protocols. While mortality from Mycoplasma infections is often low, the chronic nature, performance losses, and secondary infections can severely impact farm productivity.

To protect your livestock investment, early intervention, herd monitoring, and sourcing healthy stock remain your most effective tools.