Bacterial Osteomyelitis and Arthritis in Poultry
Bacterial osteomyelitis and arthritis are important causes of lameness in broilers and turkeys. They result most often from the hematogenous transmission of bacteria from enteric or respiratory disease; however, they can develop as a consequence of direct extension from surrounding infected tissues.
Staphylococcus aureus (also see Staphylococcosis in Poultry) and Escherichia coliare frequent causes of bacterial infections in the bones and joints of chickens, turkeys, and other birds.
Other sporadic causes of osteomyelitis and/or arthritis in poultry include coagulase-negative Staphylococcus spp, Pasteurella multocida, Ornithobacterium rhinotracheale, Trueperella (Arcanobacterium) pyogenes, Enterococcus spp (see enterococcal spondylitis images; also see Enterococcosis in Poultry), Streptococcus spp (also see Streptococcosis in Poultry), Salmonella spp (also see Salmonelloses in Poultry), Streptobacillus moniliformis, and Aspergillus spp.
Courtesy of Dr. H. J. Barnes.
Mycoplasma synoviae and Mycoplasma meleagridis (also see Mycoplasmosis in Poultry) can cause arthritis in chickens and turkeys, respectively.
Lesions of bacterial osteomyelitis and arthritis are most common in the femoral head and proximal tibiotarsus (see osteomyelitis image). Lesions at other locations, such as the metatarsus, distal femur and tibiotarsus, vertebrae, radius, and ulna, occur less commonly. In the proximal femur, the condition is referred to as femoral head necrosis, which is the most common cause of lameness in broiler chickens. Affected broilers are often > 22 days old.
Courtesy of Dr. H. J. Barnes.
Infection of bones, joints, and periarticular tissues with E coli, Staphylococcus aureus, or Staphylococcus hyicus is referred to as turkey osteomyelitis complex or green-liver osteomyelitis complex. Green discoloration of the liver associated with this complex is often observed at the processing plant but is rarely observed in birds that die or are euthanized in the field. The green hepatic discoloration is used to identify carcasses that require closer examination at slaughter.
Enterococcus cecorum is a commensal enteric bacterium that can cause epidemics of osteomyelitis, arthritis, and spondylitis in broilers and broiler breeders. Enterococcal spondylitis is a disease characterized by infection of the free thoracic and adjacent vertebrae, resulting in chronic osteomyelitis and spinal cord compression.
Clinical signs of symmetrical leg paresis and paralysis (see paralysis image) often develop in broilers 5–8 weeks old. Flock mortality varies from 5% to 15%. The pathogenesis of enterococcal spondylitis is not completely understood; however, genetically related virulent strains of E cecorum and the presence of osteochondritis dissecans lesions in the free thoracic vertebrae predisposes to development of enterococcal spondylitis.
Courtesy of Dr. H. J. Barnes.
Osteomyelitis and arthritis are detected by gross examination of articular surfaces and bone physes. Detection of subtle lesions requires histological evaluation. Affected joints are often swollen with fibrinous or caseous exudate. Bones have areas of lysis and/or replacement by caseous exudate, most often within the physis.
Response to treatment with antimicrobials currently approved for use in poultry is often poor for bacterial bone and joint infections. Antimicrobials can be used to control the bacteremia contributing to new cases. When individual birds are of high value, long-term antimicrobial therapy can improve some less severe cases. Prevention depends on adequate control and treatment of respiratory and enteric diseases that can lead to bacteremia.
Viral Arthritis in Poultry
See the chapter Viral Arthritis in Poultry.
Osteopetrosis in Poultry
Osteopetrosis in chickens is due to infection with specific strains of avian leukosis/sarcoma virus. Growth and differentiation of osteoblasts are altered by the virus, resulting in diaphyseal and/or metaphyseal, periosteal, and circumferential accumulation of woven and lamellar bone. Osteopetrosis is bilaterally symmetrical and involves the long bones, especially the tibiotarsus and tarsometatarsus (see osteopetrosis image).
Courtesy of Dr. D. Frame.
Osteopetrosis most commonly affects birds 8–12 weeks old. Lymphoid leukosis often occurs concurrently in chickens with osteopetrosis. Avian osteopetrosis differs from mammalian osteopetrosis, in which a defect in osteoclast function results in abnormal bone resorption and accumulation of primary spongiosa in the marrow cavity.
Amyloid Arthropathy in Poultry
Systemic amyloidosis with deposition of amyloid predominantly in the joints (amyloid arthropathy) can occur after infection with Enterococcus faecalis or Mycoplasma synoviae. The condition is observed rarely, and it most frequently affects the hock joint.
Brown layer chickens are particularly susceptible to amyloid arthropathy. Turkeys, broilers, guinea fowl, and other birds can also develop the disease. Some cases have been attributed to contamination of a previously sterile vaccine diluent with E faecalis during administration (eg, Marek's disease vaccine in day-old chicks). Joints can be enlarged by yellow-orange material in the articular space.
No treatment exists for amyloidosis.
Key Points
Infectious diseases of the skeleton result from bacterial infection or, rarely, viral infection.
Bacterial osteomyelitis and arthritis result from hematogenous transmission of bacteria from enteric or respiratory diseases, and they cause lameness, leg paresis, and paralysis, depending on the bones affected.
Infection by specific strains of avian leukosis/sarcoma virus in chickens can result in osteopetrosis characterized by periosteal bone deposition, as well as by thickened diaphysis and/or metaphysis of long bones.
Prevention relies on control and treatment of respiratory and enteric diseases that can lead to bacteremia.
For More Information
Nolan LK, Vaillancourt J-P, Barbieri NL, Logue CM. Colibacillosis. In: Swayne DE, ed. Boulianne M, Logue CM, McDougald LR, Nair V, Suarez DL, associate eds. Diseases of Poultry. 14th ed. Wiley Blackwell; 2020:770-830.
Logue CM, Andreasen CB, Borst LB, et al. Other bacterial diseases. In: Swayne DE, ed. Boulianne M, Logue CM, McDougald LR, Nair V, Suarez DL, associate eds. Diseases of Poultry. 14th ed. Wiley Blackwell; 2020:995-1085.
