The dog was anesthetized, and survey radiographs of the vertebral column revealed widening and lucency of the caudal physis
of L5 with loss of the normal physeal margins and a suspected pathologic fracture. Scoliosis of the thoracic vertebral column,
most likely a result of congenital vertebral abnormalities from T5 to T11, was evident. Myelographic evaluation was performed
by injecting 0.4 ml/kg iohexol into the cerebellomedullary cistern and revealed no static or dynamic compression of the spinal
cord at the level of the physeal fracture (Figure 1).
1. A lateral vertebral radiograph of the lumbar region acquired during myelography of the dog in this case. Note the widening
and lucency of the caudal physis of L5 with loss of normal physeal margins and pathologic fracture of the caudal end plate.
The caudal L4 vertebral body and the L5 vertebral body have increased opacity. There is no evidence of static or dynamic compression
of the spinal cord at the level of the physeal fracture.
Cerebrospinal fluid was collected from the cerebellomedullary cistern at the time of the myelogram. Analysis of the fluid
revealed a total protein concentration of 24 mg/dl (normal ≤ 25 mg/dl) and a nucleated cell count of 6 cells/μl (normal ≤
5 nucleated cells/μl) consisting of small lymphocytes and nonphagocytic macrophages. Aerobic bacterial culture of the cerebrospinal
fluid yielded no growth.
The patient's physical examination and radiographic findings were consistent with vertebral physitis. However, we could not
rule out a traumatic fracture or neoplastic or metabolic process affecting the physis. The owner declined additional diagnostic
tests such as bacterial cultures of the blood and urine and fluoroscopic-guided aspiration of the vertebra.
TREATMENT AND FOLLOW-UP
We suspected a bacterial cause of the vertebral physitis and initiated treatment with cephalexin (22 mg/kg orally every 8
hours for three weeks). Analgesia was provided by transdermal administration of fentanyl (2.8 μg/kg). After three days of
therapy, the dog developed mucopurulent nasal discharge and began sneezing. Enrofloxacin (5 mg/kg orally b.i.d. for 20 days)
and metronidazole (22 mg/kg orally b.i.d. for seven days) were added to treat a presumptive upper respiratory tract infection
and in an attempt to prevent pneumonia. The fentanyl patch was removed, and the patient was discharged with instructions to
the owner to firmly restrict exercise at home.
On reevaluation seven days later, the patient had mild mucopurulent nasal discharge. Pain was not evident on palpation of
the vertebral column, but the dog's gait remained stiff and short-strided in the pelvic limbs. Three weeks after the initial
examination, the antibiotic therapy was discontinued.
Four weeks after the initial examination, the dog was reevaluated for recurrent crying, panting, and shaking. The patient
was in extreme pain upon palpation of the lumbar vertebrae; however, the gait remained unchanged from previous examinations.
Complete blood count and serum chemistry profile results were within reference ranges. Cystocentesis was performed, and a
urinalysis revealed a moderate amount of a mixed population of bacteria that were predominantly bacilli. Aerobic bacterial
culture of the urine grew > 105 colonies/ml of Escherichia coli and > 105 colonies/ml of Enterococcus species. An aerobic bacterial culture of the blood yielded no growth. The results of immunofluorescent antibody testing for
Brucella canis were negative.
The dog was anesthetized, and vertebral radiographs were obtained of the previously affected site. Degenerative changes of
the caudal physeal region of L5 and bony callus formation ventral and lateral to the pathologic fracture were evident (Figure 2). We reinstituted antibiotic therapy consisting of cephalexin (22 mg/kg orally every 8 hours) and enrofloxacin (5 mg/kg orally
every 12 hours). Forty-eight hours later, the patient's gait and level of pain improved dramatically, and the patient was
discharged with physical activity restriction instructions.
2. A lateral vertebral radiograph taken on Day 28 revealed degenerative changes of the caudal physeal region of L5 and bony
callus formation ventral to the physeal fracture.