The findings on the neurological examination are compatible with C6-T2 myelopathy
Troy has neurological deficits, and therefore is neurologically abnormal. Given that his mentation is normal and he does not have any cranial nerve deficits, his neurological problem is most likely involving the spinal cord or motor unit. Since we cannot evaluate Troy's gait (he will not walk!) or his CPs, we must localize his problem based on what we do know about him.

He has conscious proprioceptive deficits in his pelvic limbs with normal reflexes. This means that he has an upper motor neuron problem affecting his pelvic limbs. This means that his neurological problem must be cranial to the L3 spinal cord area.

He has reduced withdrawal reflexes in his thoracic limbs. These are lower motor neuron signs, which means that he must have a problem affecting his C6-T2 area of his spinal cord.

A C6-T2 myelopathy would cause lower motor neuron deficits in his thoracic limbs, AND the upper motor neuron deficits in the pelvic limbs. A problem in this area may also explain his marked neck pain).

Based on the signalment and history, the most likely cause of Troy's neurological problem is infection.
Inflammatory disease such as steroid responsive meningitis is possible, but usually dogs with this disease do not have neurological deficits, although they do have marked cervical pain. Other inflammatory diseases such as GME (granulomatous meningoencephalomyelitis) usually affect small breed dogs. Neoplasia may affect dogs of any breed and age, but usually dogs are older than 5 years of age. Caudal cervical spondylomyelopathy usually affects middle aged Doberman Pinchers.

The abnormalities on these radiographs are compatible with diskospondylitis.
There are severe osteolytic changes of the caudal endplate of C6 and the cranial endplate of C7. Marked sclerosis of both these vertebral bodies as well as osteoproductive change is seen on the VD projection. C6-7 appears malaligned. The C7 vertebral body appears misshapen. (The remainder of the vertebral column radiographs are normal.) These radiographic findings are compatible with discospondylitis.

Dogs with discospondylitis do not usually have neurological deficits, but they may if they have granulation tissue compressing the spinal cord secondary to the discospondylitis, luxation, or an extension of the infection to the epidural space ("epidural empyema"), meninges, spinal cord. The cause of the myelopathy remains unknown as further diagnostics were not done-but the major differentials include: granulation tissue, instability secondary to discospondylitis, empyema (infection of the epidural space), and myelitis.

Discospondylitis is an infection of the intervertebral disc and adjacent vertebral bodies; often multiple discs are affected. The cause is bacterial or fungal. The organism gains access to the disc by direct inoculation, (bite wound), grass awn migration, or hematogenous routes (dentistry, endocarditis, urinary tract infection extending to involve the intervertebral veins).

In an attempt to isolate the causative organism, blood and urine cultures were done. A percutaneous disc space aspirate (for aerobic, anaerobic, fungi culture and cytology) was not done due to the cervical location (best done on dogs with lumbar discospondylitis). A lumbar cerebrospinal fluid tap was done, which was normal.

There was no growth on the cultures.

The best treatment for this dog is long-term broad spectrum antibiotics.
Treatment is long-term antibiotics, ideally based on culture and sensitivity, along with rest and analgesics. If there is no growth on culture, then I usually start treatment with cephalexin or clavamox. It is important to monitor these dogs closely with rechecks every 6 weeks along with repeat radiographs. The entire vertebral column should be radiographed, so that the "old" lesion can be monitored radiographically, but also so that the dog can be screened for "new" lesions. Clinical improvement is usually seen within 10-14 days. The minimum treatment is for 6 weeks-general guidelines are to treat 4 weeks beyond static radiographs. The prognosis is good for bacterial disease, poor for fungal disease.

OUTCOME
Troy was treated with injectable cefazolin at 25 mg/kg IV b.i.d. for three days, followed by oral cephalexin at 20 mg/kg twice daily. He improved dramatically after 2 days of therapy. (click to see flash video - this is a 1.5MB file, loading slowly.) He was treated for 6 months with antibiotics. At the time of his last examination, he had a normal physical examination, neurological examination, and radiographically, the C6-7 vertebrae had fused. (click to see flash video - this is a 1.5MB file, loading slowly.)

   

Discospondylitis is a common cause of spinal pain in the dog. It is caused by a bacterial or fungal infection of the intervertebral disc and adjacent vertebral bodies. Multiple disc spaces are often involved. Usually young, large breed dogs are affected, but it may occur in any age, sex or breed of dog. Dogs usually have an insidious onset of disease, but then a rapidly progressive history. Owners most commonly report trouble rising, reluctance to jump, and pain.

Dogs with discospondylitis may be systemically ill, and many have a fever. They do not usually have neurological deficits, but are usually extremely painful, often in multiple locations along the vertebral column. A complete neurological examination, including a fundic examination should be done. A minimum data-base should be completed to evaluate for systemic disease, followed by a complete set of vertebral column radiographs. On radiographs, there is end plate destruction, bony production, collapse of the intervertebral disc (may also appear wider due to end plate destruction). Blood culture, urine cultures and ideally a disc space aspirate should be done to identify the causative agent. Treatment for bacterial discospondylitis is long-term antibiotics, ideally based on culture and sensitivity results, along with rest and analgesics. Dogs should be examined and re-radiographed (the entire vertebral column) every 6 weeks. The prognosis is good for bacterial discospondylitis, but poor for fungal discospondylitis.

For additional educational opportunities please plan to attend the 78th Western Veterinary Conference February 19 - 23, 2006. Relevant links from the 2006 WVC Program: Cervical pain: It doesn't have to be a pain in your neck! (V180) Functional Anatomy & Pathology of the Canine Spine (V269) Acute Spinal Disease (Symposium Session) (S7AP)