Signalment & History
A 12 year old FI Airedale Terrier presents for further evaluation of her left limb lameness of 1 week duration. The owner also noted a discolored vulvar discharge which began today. At presentation she is very weak and unable to walk. On physical examination, she has pink mucous membranes, CRT >3 sec, RR 35 bpm, HR 100 bpm, 102.7 °F, no murmur and strong synchronous pulse. She is severely painful and cries whenever any manipulation or palpation is tried.
Findings
There is a tubular soft tissue opaque structure in the mid caudal abdomen, ventral to the colon and dorsal to the urinary bladder, measuring approximately 25 mm in diameter. Additionally, there is a large, ill-defined, soft tissue opaque structure, with smooth margins, in the mid-cranial ventral abdomen, caudal to the liver. This structure is best seen on the right lateral projection and it is thought to represent the splenic tail. The serosal abdominal detail is adequate. Moreover, narrowing of the disc spaces at T13-L4, the lumbosacral space and throughout the caudal thoracic spine is noted. In addition there is moth-eaten end plate lysis at T8-10 and T13-L4. Associated ventral spondylosis deformans is seen throughout this region. Particularly, the L7-S1 intervertebral disc space is severely narrowed with sclerosis of the vertebral end plates and moderate spondylosis deformans. There is also the presence of mild, smoothly marginated osseous proliferation on all the lumbar articular facets. There is moderate, unstructured interstitial pulmonary pattern in the ventral periphery of the right middle and caudal lung lobes included in the study.
Diagnosis
You have found a tubular soft tissue opaque structure in the mid caudal abdomen, ventral to the colon and dorsal to the urinary bladder, measuring approximately 25 mm in diameter. In addition you noted a large, ill-defined, soft tissue opaque structure, with smooth margins, in the mid-cranial ventral abdomen, caudal to the liver, most likely representing the splenic tail. Furthermore, you recognized narrowing of the disc spaces at T13-L4, the lumbosacral space and throughout the caudal thoracic spine. In addition moth-eaten end plate lysis at T8-10 and T13-L4 was noted. Associated ventral spondylosis deformans was seen throughout this region. Also, you found a moderate, unstructured interstitial pulmonary pattern in the ventral periphery of the right middle and caudal lung lobes included in the study. These radiographic abnormalities are consistent with: uteromegaly (differentials include: pyometra, hydrometra, mucometra or hemometra); multifocal thoracic and lumbar discospondylitis with severe lumbosacral spinal degenerative changes, mild osteoarthrosis of the articular facets of the lumbar spine and multifocal thoracic and lumbar intervertebral disc narrowing suggestive of intervertebral disc disease; moderate, ventrally distributed, right sided unstructured interstitial pulmonary pattern (primary differential is aspiration pneumonia with potential fibrosis).
Conclusions
Discospondylitis is an inflammation of the intervertebral disk, associated end plates, and adjacent vertebral bodies, causing destruction and proliferation of bone. The most common cause is bacterial infection with coagulase positive Staphylococci (S. aureus or S. intermedius) being the most frequent isolate. Other frequently identified bacteria include Streptococcus, Escherichia coli, and Brucella canis. Fungal infections have also been reported. Discospondylitis most commonly arises from hematogenous spread of organism to the disc space, subsequently extending to the adjacent vertebrae. Infection may originate from bacteriemia associated with urogenital tract infections, skin or dental disease, and valvular endocarditis. The diagnosis is ultimately based upon demonstrating the bony lysis of the vertebral end plates with vertebral body osteolysis, shortening of the vertebral bodies and proliferative sclerosis and osseous bridging and narrowing of disc spaces in later stages. However development of the radiographic abnormalities may take 2 to 6 weeks after infection. Unremarkable findings cannot rule out the existence of discospondylitis as it can take time for radiographic changes to develop. Pyometra is an infection of the uterus which occurs under the control of hormones produced by the intact female dog. The most common pathogen causing pyometra is E.coli. This patient’s uterine and blood culture resulted positive for E.Coli. During surgery, this patient’s spleen was found to be abnormal and folded in on itself, so it was removed prophylactically in order to avoid post-op splenic torsion. Pathology report revealed a partial splenic torsion.
Discospondylitis is defined as an inflammation or infection of the intervertebral disk and osteomyelitis in adjacent vertebral end plates and bodies. Discospondylitis most commonly arises from hematogenous spread of organism to the disc space. Primary source can be the urogenital tract, skin or dental disease, valvular endocarditis, migrating foreign bodies (such as grass awns), extending body organ abscesses, iatrogenic trauma (such as spinal surgery or fenestration) and epidural injections. Discospondylitis typically affects young to middle aged dogs. Purebread, large-breed and male dogs are more often affected. It is very rare in cats. Clinical signs are variable. They range from systemic depression, anorexia, fever and weight loss to stiffness and reluctance to walk and jump. Spinal or paraspinal hyperesthesia is the most characteristic sign. Extension of inflammation can lead to neurologic signs due to extradural compression and to meningitis and meningomyelitis. The course of the disease is usually slowly progressive but vertebral pathologic fractures or intervertebral disc protrusion can lead to acute deterioration of clinical signs. The sites most commonly affected are L7-S1, caudal cervical, midthoracic, and thoracolumbar spine. The diagnosis is suggestive from patient history and physical and neurological examinations. A definitive diagnosis is made on the basis of characteristic findings on radiographs. Blood and urine cultures should be obtained before starting antibiotic therapy. An aggressive long-term antibiotic therapy for at least 2-4 months is mandatory. Analgesics may be necessary. Prognosis is usually favorable if neurological signs are mild, unless multiple lesion, vertebral fracture, instability or dislocation occurs. Prognosis may be guarded in dogs with fungal infections or infection with Brucella canis (!!! zoonosis!!!).
References
Inflammatory Diseases of the Spine in Small Animals. Tipold A, Stein VM. Vet Clin Small Anim (40) 2010 871-879.
