What it looks like
Coughing and sneezing — Persistent dry or moist cough; occasional sneezing; birds may shake head to clear mucus
Nasal discharge or foamy eyes — Discharge from nostrils; eyes may be swollen, watery, or crusted with dried discharge
Facial swelling (sinusitis) — Face appears puffy; area below eyes swollen; indicates sinus inflammation
Rales or abnormal breathing sounds — Rattling or wheezing sounds when bird breathes; detected with stethoscope or close listening
Poor growth and reduced feed intake — Chicks fail to thrive; eat less than healthy flockmates; appear weak
Ruffled feathers and lethargy — Feathers appear unkempt; birds are inactive and depressed
Reduced egg production and soft/rough eggshells — Hens lay fewer eggs; shells are thin, soft, or crinkled
Likely causes
- Infection with Mycoplasma gallisepticum (MG), a bacterium that colonizes air sacs and respiratory tract
- Transmission through respiratory droplets, contaminated feed/water, or contact with infected birds
- Vertical transmission from infected hens to chicks through eggs (in some strains)
- Stress (transport, overcrowding, poor ventilation, vaccination) triggering clinical disease
- Secondary bacterial infections (E. coli) worsening respiratory signs
What to do
Treat with broad-spectrum antibiotics (tetracycline, macrolide) for 5-7 days under veterinary supervision. Follow label directions and withdrawal periods. Antibiotics reduce clinical signs but do not eliminate the organism; birds remain carriers. Provide supportive care: clean water, nutritious feed, warmth, and stress reduction. Improve ventilation and litter management.
When to see a vet
See a vet if your bird shows severe signs or doesn’t improve within a few days of treatment.
Prevention
Source birds from MG-negative flocks. Practice strict biosecurity: separate by age, quarantine new birds for 3 weeks, avoid contact with other poultry operations. Disinfect equipment and housing. Maintain excellent ventilation to reduce ammonia and respiratory irritation. Test breeding flocks for MG status if possible. Cull positive birds to maintain negative flock status.
Frequently asked questions
What is chronic respiratory disease?
CRD is caused by Mycoplasma gallisepticum (MG), a bacterium that colonizes the respiratory tract and air sacs. It causes persistent respiratory signs, reduced growth, and lower egg production. Stress and secondary infections worsen the disease.
Is CRD contagious?
Yes, highly contagious through respiratory droplets. MG spreads rapidly in crowded conditions. Infected birds may transmit the disease vertically (through eggs) to chicks, establishing infection in the next generation.
Can antibiotics cure CRD?
Antibiotics reduce clinical signs and improve performance temporarily, but they do not eliminate MG. Birds remain carriers and can transmit the disease. Long-term control requires biosecurity and culling of positive birds.
Should I cull birds with CRD?
For valuable breeding birds, antibiotic treatment and isolation may be considered. For commercial flocks, culling positive birds is more effective for long-term flock health. Discuss options with your veterinarian.
How do I prevent CRD in my flock?
Source birds from MG-negative flocks. Quarantine new birds for 3 weeks. Maintain strict biosecurity (no contact with other operations). Ensure good ventilation and litter management. Have breeding flocks tested for MG status.