Mycoplasmosis is a respiratory disease caused by a bacterial infection.
The symptoms, which are slow to develop, resemble the symptoms of a standard respiratory infection: Watery eyes, dirty nostrils, coughing and sneezing. It also causes decreased egg production, lowered fertility and decreased hatchability. There are various species of Mycoplasma that can infect chickens, but the most common in small flocks is Mycoplasma gallisepticum (MG). The disease can have a long course of infection and can lead to the accumulation of a “cheesy” material in the eyelids and sinuses as well as noticeable outward swelling.
Can it spread?
Chickens that recover from MG remain asymptomatic carriers for life. Therefore, introduction of seemingly healthy birds to an uninfected flock can become a source of infection. Infected breeders can transmit the disease through their eggs to the chicks, further perpetuating the disease.
The best prevention for MG is to purchase MG-free chickens. This is often easier said than done, as carrier chickens look perfectly healthy. A simple and inexpensive blood test performed by most veterinary diagnostic laboratories can detect previous exposure to MG. Contact your veterinarian, your local extension office or the local university to find an expert who can help you diagnose and treat your chickens.
Sick chickens benefit from lowered stress, reduced dust and clean coops, as well as from proper nutrition and antibiotic treatment. Tylosin and tetracycline antibiotics can help reduce symptoms, but cannot eliminate the infection or cure a carrier chicken.
Antibiotics are best administered through drinking water at the dosage indicated on the label and used no longer than for seven days. There are live and inactive vaccines available, but their use is only practical for large flocks of laying chickens to protect egg production. The use of live vaccines is regulated by most states and should be used with care, as some live vaccines can cause disease in other poultry species, especially turkeys.
About the Authors: Dr. Jose A. Linares, DVM, ACPV, is the Resident Director of the Texas Veterinary Medical Diagnostic Laboratory, Poultry Diagnostic Laboratory in Gonzales, TX. Dr. John El-Attrache, PhD, is an Assistant Professor in the Department of Veterinary Pathobiology in the College of Veterinary Medicine at Texas A&M University.