Coagulase-positive staphylococci (also see Staphylococcosis) are frequently responsible for bacterial infections in the bones and joints of broiler chickens. Mycoplasma synoviae (see Mycoplasmosis: Mycoplasma synoviae Infection in Poultry) may also play a role in infectious bone disorders and can be monitored serologically.

In broilers, bacterial infections are most common in the proximal femur and proximal tibiotarsus when the birds are >22 days of age. In the proximal femur, the condition is also referred to as femoral head necrosis. Recent reports indicate this is the most common cause of lameness in broilers. The etiology appears dependent on vertically transmitted staphylococci, often in combination with a challenge by immunosuppressive viruses (eg, infectious bursal disease, see Infectious Bursal Disease). Floor eggs have been shown to be common carriers of staphylococci, so their use should be minimal. A high standard of hatchery hygiene can reduce this risk. Formaldehyde fumigation within the hatchers is also likely to help. In addition, hatchery fluff samples can be examined to monitor for contamination with staphylococci.

Staphylococcal infections in joints and tendons are also seen in breeders. Outbreaks are often due to bacterial infection subsequent to an existing tendinitis. A history of other diseases such as coccidiosis is often associated with an increase in staphylococcal infections in breeders. In some instances reoviruses may also be isolated, although they are more likely to be opportunist pathogens accentuating existing pathologies. (Also see Viral Arthritis). The virus is egg transmitted. Vaccines against the condition have been developed.

Escherichia coli is often responsible for flock outbreaks of arthritis and osteomyelitis in broiler chickens and turkeys. These outbreaks may be associated with respiratory disease. Pasteurella multocida has been isolated from arthritic joints in broiler breeders following use of live vaccines. Other sporadic causes of arthritis in poultry include Salmonella spp and Streptobacillus moniliformis.

Bacterial bone and joint infections often show a poor response to antibiotic treatment. Antibiotics may be used to control the bacteremia contributing to new cases and to modify the bacterial flora within a flock. When individual birds are of high value, injections of long-acting antibiotics may improve some less severe cases. Control requires minimizing sources of infection and stock susceptibility.

Amyloidosis

Extensive amyloid arthropathy is primary caused by Enterococcus faecalis, but not by all isolates. Clinical cases are seen only occasionally and most frequently affect the hock joint of a few replacement pullets or broiler breeders. Cases may be attributed to the contamination of a previously sterile vaccine diluent with E faecalis during administration (eg, Marek's vaccine in day-old chicks).

Last full review/revision March 2012 by Barry H. Thorp, BVMS, PhD, MRCVS