Mycoplasma synoviae
Synonyms: MS, infectious synovitis, synovitis, silent air sac
Species affected: chickens and turkeys.
Clinical signs: Birds infected with the synovitis form show lameness, followed by lethargy, reluctance to move, swollen joints, stilted gait, loss of weight, and formation of breast blisters. Birds infected with the respiratory form exhibit respiratory distress. Greenish diarrhea is common in dying birds (see Table 1). Clinically, the disease in indistinguishable from MG.
Staphylococcus
Synonyms: staph infection, staph septicemia, staph arthritis, bumblefoot .
Species affected: All fowl, especially turkeys, chickens, game birds, and waterfowl, are susceptible.
Clinical signs: Staphylococcal infections appear in three forms -- septicemia (acute), arthritic (chronic), and bumblefoot. The septicemia form appears similar to fowl cholera in that the birds are listless, without appetite, feverish, and show pain during movement. Black rot may show up in eggs (the organism is passed in the egg). Infected birds pass fetid watery diarrhea. Many will have swollen joints (arthritis) and production drops (see Table 3).
The arthritic form follows the acute form. Birds show symptoms of lameness and breast blisters, as well as painful movement (see Table 3). Birds are reluctant to walk, preferring to sit rather than stand.
Marek's Disease
Synonyms: acute leukosis, neural leukosis, range paralysis, gray eye (when eye affected)
Species affected: Chickens between 12 to 25 weeks of age are most commonly clinically affected. Occasionally pheasants, quail, game fowl and turkeys can be infected.
Clinical signs: Marek's disease is a type of avian cancer. Tumors in nerves cause lameness and paralysis. Tumors can occur in the eyes and cause irregularly shaped pupils and blindness. Tumors of the liver, kidney, spleen, gonads, pancreas, proventriculus, lungs, muscles, and skin can cause incoordination, unthriftiness, paleness, weak labored breathing, and enlarged feather follicles. In terminal stages, the birds are emaciated with pale, scaly combs and greenish diarrhea (see Table 2).