Vertebral Osteomyelitis (Spondylitis) in Chickens

See your vet immediately if your chicken cannot stand, is dragging one or both legs, or is sitting with both legs stretched forward. Vertebral osteomyelitis, often called spondylitis, is an infection and inflammation of one or more vertebrae. In chickens, the infection often affects the free thoracic vertebra and nearby spinal bones. As swelling, bone damage, and caseous material build up, the spinal cord can be compressed, which leads to pain, weakness, and paralysis.

In poultry medicine, this problem is often discussed as enterococcal spondylitis when Enterococcus cecorum is involved. That organism normally lives in the intestinal tract of many birds, but certain strains can move beyond the gut, enter the bloodstream, and settle in vulnerable bone. Other bacteria, including Staphylococcus species, can also cause vertebral infection.

This condition is seen most often in fast-growing broiler and broiler-breeder chickens, but any chicken with bacterial spread, wounds, poor mobility, or underlying stress can be at risk. For backyard flocks, the biggest concern is not only the affected bird's comfort, but also whether there is a management or infectious issue that could affect other birds.

The most recognized cause of vertebral osteomyelitis in chickens is pathogenic Enterococcus cecorum. This bacterium can live in the gut without causing obvious illness, but some strains are linked to outbreaks of skeletal disease, especially in broilers and broiler breeders. Research suggests the process often starts with intestinal colonization, then bacteria enter the bloodstream and seed the free thoracic vertebra, where spinal lesions later develop.

Other bacteria can also cause vertebral infection. Staphylococcus species are important because they can enter through skin wounds and then spread to joints and bone, including vertebrae. In poultry, vertebral osteomyelitis may also be part of a broader septicemic or opportunistic bacterial problem rather than a single isolated spinal disease.

Risk factors are often a mix of bird factors and flock factors. Fast growth, stress, poor litter quality, skin injuries, immunosuppressive disease, hatchery contamination, and sanitation problems may all increase the chance that bacteria move from the environment or gut into deeper tissues. In some birds, microscopic damage or developmental weakness in the vertebra may make it easier for bacteria to establish infection there.

For backyard flocks, that means the visible spinal problem is often only part of the story. Your vet may want to look at housing, footing, crowding, pecking injuries, water sanitation, and the health history of the whole flock.

Diagnosis starts with a hands-on exam and a careful history. Your vet will ask when the lameness started, whether the bird can still stand, what the droppings and appetite are like, and whether other flock mates are affected. Because paralysis in chickens has many causes, the exam usually focuses on both neurologic and orthopedic clues.

In a live bird, your vet may recommend radiographs to look for vertebral enlargement, collapse, or other spinal changes. Imaging can support suspicion, but it does not always identify the exact bacterium. If the bird dies or humane euthanasia is chosen, necropsy is often the most useful next step. Affected vertebrae may contain inflammatory material and can visibly compress the spinal cord.

To confirm the cause, your vet may submit samples for bacterial culture and, when available, susceptibility testing. Merck notes that isolation of Enterococcus from lesions confirms enterococcosis, and blood agar culture is commonly used. Culture matters because some bacteria are contaminants in the environment, while others are true pathogens, and treatment choices depend on knowing which is which.

Your vet may also discuss differentials such as Marek's disease, trauma, fractures, severe joint infection, and other septicemic bacterial diseases. In flock cases, testing one or more birds through a veterinary diagnostic laboratory can be more informative than trying to treat blindly.

Prevention focuses on lowering bacterial exposure and reducing the conditions that let bacteria move from the gut or skin into deeper tissues. Keep housing clean and dry, manage litter well, sanitize water systems, and reduce sharp edges, protruding wire, splinters, and other injury risks. Good footing matters too, because birds that slip, pile up, or develop skin wounds may be more vulnerable to secondary bacterial infection.

Flock health also matters. Work with your vet to reduce stress, crowding, and underlying disease that can weaken immunity. Merck notes that enterococcosis often occurs secondary to another problem, so preventing immunosuppressive disease and maintaining strong general husbandry can lower risk. In hatchery or breeding settings, sanitation is especially important because bacterial contamination can affect chicks very early in life.

If you add new birds, quarantine them and watch closely for lameness, weakness, diarrhea, or poor thrift. Source birds from reputable flocks when possible. For commercial systems, control programs for Mycoplasma synoviae in breeder flocks have reduced infection pressure in the US, and similar attention to biosecurity helps limit other infectious causes of skeletal disease.

Finally, act early. A single lame chicken may be an isolated injury, but multiple birds with weakness or paralysis deserve prompt veterinary input. Early investigation can protect the rest of the flock and may prevent losses from a problem that is much easier to manage at the start than after paralysis appears.