Vertebral Osteomyelitis and Spinal Abscess in Sheep: Neck Pain, Ataxia, and Weakness

Vertebral osteomyelitis means infection and inflammation of one or more vertebrae. A spinal or perivertebral abscess is a pocket of infection that forms in or around the spine. In sheep, these problems matter because swelling, bone destruction, and pus can narrow the spinal canal and press on the spinal cord. That pressure can cause pain, incoordination, weakness, and eventually an inability to stand.

In practice, sheep with cervical disease often show neck pain, low head carriage, restricted neck movement, ataxia, and weakness in all four limbs. Some cases involve the vertebral bodies themselves, while others involve nearby tissues or joints around the neck, such as the atlanto-occipital region in young lambs. The exact location changes the signs, but spinal cord compression is what makes this an emergency.

These infections are usually bacterial rather than genetic or nutritional. They may start after bacteria enter through the navel, skin wounds, tail docking or castration sites, or another septic focus and then spread through the bloodstream. In the cervical area, infection can also follow injections placed in the neck with contaminated needles or irritating products. Your vet can help sort out whether the problem is infectious, traumatic, metabolic, or another neurologic disease.

Most cases are caused by bacteria reaching the spine. One common route is hematogenous spread, meaning bacteria travel in the bloodstream from another infected site. In lambs, that may begin with navel ill, joint ill, or infection entering through docking, castration, or skin wounds. Once bacteria seed bone, joints near the spine, or surrounding soft tissues, an abscess can form and start compressing the spinal cord.

In the neck, perivertebral abscesses can also develop after injections given with dirty needles or after irritating substances are injected into neck muscles. This is an important management point on farms because the cervical region is close to the spinal canal, and even a localized abscess can create major neurologic signs.

Other infectious conditions can complicate the picture. Caseous lymphadenitis, caused by Corynebacterium pseudotuberculosis, creates internal and external abscesses in sheep and can be difficult to recognize before death. Not every sheep with weakness has a spinal abscess, though. Trauma, vertebral fracture, listeriosis, maedi-visna, parasitic migration, metabolic disease, and copper-related disorders can all mimic spinal infection, which is why a hands-on exam matters.

Your vet usually starts with a full history and neurologic exam. Details that help include the sheep's age, whether signs came on suddenly or gradually, any recent lambing problems, navel infections, joint swelling, injections in the neck, wounds, fever, or flockmates with similar issues. The exam helps localize the lesion to the neck, thoracolumbar spine, or another part of the nervous system.

Imaging is often the next step. Radiographs can show vertebral destruction, new bone formation, or loss of normal spinal architecture associated with osteomyelitis or perivertebral infection. In the cervical region, ultrasound can sometimes identify a perivertebral abscess or soft tissue swelling, especially when there is a palpable mass. In referral settings, advanced imaging may be considered, but on many farms the diagnosis is made from the combination of history, exam findings, and field imaging.

Additional tests may include CBC and chemistry, culture of accessible pus, and sometimes cerebrospinal fluid or contrast studies if your vet feels they are appropriate. Necropsy is also valuable when a sheep dies or is euthanized, because it can confirm the diagnosis and help protect the rest of the flock by identifying likely sources such as navel ill, injection-site infection, or caseous lymphadenitis.

Prevention starts with reducing opportunities for bacteria to enter the body. In lambs, clean lambing areas, dry bedding, and prompt navel care are key because navel ill and joint ill can seed infection elsewhere, including the spine. Watch young lambs closely for fever, swollen joints, stiffness, poor nursing, or an arched back, and involve your vet early when those signs appear.

Injection hygiene also matters. Use clean needles, change needles often, avoid injecting contaminated or irritating material, and follow your vet's preferred handling and restraint practices. Cervical soft tissue infections can become perivertebral abscesses, so careful technique is more than a routine detail.

Flock biosecurity helps too. Do not introduce sheep with unexplained abscesses or enlarged lymph nodes until they have been evaluated, because caseous lymphadenitis can spread through pus and contaminated equipment. Good shearing and wound-care hygiene, lower stocking stress, and prompt treatment of skin wounds all reduce bacterial spread.

Finally, work with your vet on a flock health plan that includes lambing hygiene, early recognition of septic disease, and judicious antimicrobial use. If a sheep dies with neurologic signs, necropsy can be one of the most useful prevention tools because it may identify the source of infection and help protect the rest of the flock.