3. A lateral vertebral radiograph taken on Day 48. Note the bony callus and ventral ossification of L5 indicating further
remodeling of the previous physitis site.
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Twenty days later (Day 48), the patient did not show signs of pain upon palpation of the vertebral column; its gait remained
unchanged from previous examination findings. Radiographs of the lumbar region were consistent with further remodeling of
the caudal physeal region of L5 (Figure 3). We continued the cephalexin and enrofloxacin for an additional 12 weeks. During reevaluation on Days 90 and 138, the dog
did not show evidence of pain, but the stiff, short-strided pelvic limb gait remained.
DISCUSSION
This case describes a dog that had poorly localized pain. Conditions that result in generalized pain or pain that is difficult
to localize to a specific area include diseases that affect the intervertebral disks, facet joint capsules, dorsal root ganglia
and sensory nerves, vertebral ligaments, musculature, periosteum, or meninges.1 Because of the diagnostic test results as well as the patient's response to therapy, it was ultimately determined that the
dog had vertebral physitis.
Types of vertebral infections
Vertebral infections are classified based on the portion of the vertebra affected or the surrounding structures affected.
Discospondylitis is an infection of the intervertebral disk and adjacent vertebral end plates, resulting in symmetrical lysis
of the vertebral end plates with reactive sclerosis in the vertebral bodies.2-4 Vertebral physitis is inflammation, lysis, and reactive bone involving the caudal physeal zone of affected vertebrae without
involvement of the intervertebral disk.2-4 Vertebral osteomyelitis or spondylitis is an infection confined to the vertebral body.4
Vertebral physitis occurs primarily in dogs under 2 years of age.2 In contrast, discospondylitis occurs most commonly in middle-aged to older dogs.2 In cases of vertebral physitis, the lumbar vertebrae are most frequently affected.2 In cases of discospondylitis, common areas include the thoracic and lumbar vertebral column and the lumbosacral disk space,
but any intervertebral disk space can be affected.4-6 Vertebral osteomyelitis is seen more commonly in horses and ruminants than in small animals7-11 ; it can occur at any vertebra. In ruminants, vertebral osteomyelitis has been diagnosed concurrently with an adjacent spinal
abscess known as epidural empyema. Epidural empyema has been reported in ruminants as well as dogs.10-15
Causes
Migrating plant awns (grass seeds, foxtails) have been described as a cause of discospondylitis and vertebral osteomyelitis
in dogs in certain regions in the United States. Other causes of vertebral infections may include penetrating wounds, extension
of an infection adjacent to the vertebrae, epidural anesthesia, or previous disk or vertebral surgery. Many cases of vertebral
infection do not have an apparent source of infection.4,5
Most vertebral infections are thought to develop through hematogenous spread of bacteria or fungi from a primary infection
involving other areas of the body such as the urogenital tract, skin, heart valves, and oral cavity.2,4,5 Urinary tract infections are often associated with vertebral infections, but a direct effect is rarely proved.4 However, similarities exist between the common age at which dogs are affected by vertebral infections and urinary tract
infections. Dogs under the age of 3 years were shown to be at an increased risk for recurrent or persistent urinary tract
infections, while dogs older than 10 years of age were at a decreased risk for recurrent urinary tract infections.16 Urogenital infections may be more common in young animals, and, although there may not be a direct correlation, dogs that
have vertebral infections are more commonly younger or middle-aged.2 Urinary tract infections may not be associated with vertebral infections since urinary tract infections occur more frequently
in female dogs than in males, whereas discospondylitis is more common in males.17,18
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