What Is Your Diagnosis?

Erin Y. Akin Small Animal Teaching Hospital, Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849.

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Jill Narak Small Animal Teaching Hospital, Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849.

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Stephen T. Simpson Small Animal Teaching Hospital, Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849.

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 DVM, MS, DACVIM

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History

A 5.5-year-old castrated male miniature Dachshund was evaluated for an acute onset of reluctance to move its tail. The dog had a 1-week history of difficulty defecating and signs of pain when its tail was manipulated. The dog's medical history included an episode of signs of neck pain 4 months previously and detection of intervertebral disk extrusion at C2–3, which was successfully treated with a ventral slot decompression procedure.

Physical examination at the time of admission revealed a body condition score of 7 out of 9. Otherwise, findings were normal with the exception of signs of pain detected on neurologic examination. The neurologic examination revealed normal mentation, cranial nerve function, gait, and posture. Postural reactions and spinal reflexes were normal; perineal reflexes and anal tone were preserved. Signs of severe discomfort were elicited upon manipulation of the dog's tail; signs of pain could not be elicited elsewhere in the paravertebral region. On the basis of the results of neurologic examination, the lesion was localized to the sacrum and caudal vertebrae. Radiographs of the lumbosacral portion of the vertebral column were obtained while the dog was under general anesthesia (Figure 1).

Figure 1—
Figure 1—

Lateral (A) and ventrodorsal (B) radiographic views of the lumbosacral portion of the vertebral column of a 5.5-year-old castrated male miniature Dachshund evaluated because of an acute onset of reluctance to move its tail. The dog had a 1-week history of difficulty defecating and signs of pain when its tail was manipulated.

Citation: Journal of the American Veterinary Medical Association 238, 2; 10.2460/javma.238.2.153

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Diagnostic Imaging Findings and Interpretation

A mineralized disk is evident at L7-S1; the disk is slightly displaced dorsally. Spondylosis is seen ventrally at this site as well, suggesting a chronic process. Additionally, there is mineralized material in the intervertebral foramen at Cd1–2 (Figure 2). Comparison of these radiographic images with those obtained 4 months earlier (Figure 3; during the patient's previous evaluation for intervertebral disk disease) indicates that a mineralized disk at Cd1–2 was present at that time.

Figure 2—
Figure 2—

Same lateral radiographic image as in Figure 1. A mineralized disk is evident at L7–S1; the disk is slightly displaced dorsally (asterisk). Spondylosis (white arrow) is seen ventrally at this site as well, suggesting a chronic process. Additionally, there is mineralized material in the intervertebral foramen at Cd1–2 (black arrow).

Citation: Journal of the American Veterinary Medical Association 238, 2; 10.2460/javma.238.2.153

Figure 3—
Figure 3—

Lateral radiographic view of the lumbosacral portion of the vertebral column of the same dog as in Figure 1 that was taken 4 months earlier. Notice the mineralized disk at Cd1–2 (arrow).

Citation: Journal of the American Veterinary Medical Association 238, 2; 10.2460/javma.238.2.153

Computed tomography of the vertebral column was also performed while the dog was under general anesthesia. Transverse images at Cd1–2 revealed a large amount of mineral density within the vertebral canal; this material extended out of the intervertebral foramen cranially within the vertebral canal to the level of Cd1 (Figure 4). Transverse images of the junction of the sacrum and caudal vertebrae revealed material of increased density in the central aspect of the spinal canal. Spondylosis deformans ventrally and laterally on the left side were present at the lumbosacral junction. Other findings included stenosis of the left lumbosacral intervertebral foramen and, at the caudal aspect of L7, an ovoid soft tissue density in the left aspect of the vertebral canal, most likely representing an enlarged spinal nerve. The vertebral canal at the lumbosacral junction was stenotic, and there was a decreased amount of epidural fat at this location. Differential diagnoses included intervertebral disk disease, hemorrhage, both, or other dystrophic mineralization.

Figure 4—
Figure 4—

Transverse computed tomographic image (slice thickness, 1 mm) at the level of Cd1–2 of the same dog as in Figure 1. Notice the mineral density within the vertebral canal (arrow).

Citation: Journal of the American Veterinary Medical Association 238, 2; 10.2460/javma.238.2.153

Comments

A dorsal laminectomy was performed from S3 through Cd2. An abundant amount of extruded intervertebral disk material was observed in the vertebral canal; some disk material was adhered to spinal nerves. The disk material was removed, and the intervertebral disks at S3-Cd1 and Cd1–2 were fenestrated.

The patient was maintained on a constant rate infusion of fentanyl (3 μg/kg/h [1.4 μg/lb/h], IV) during surgery and for 24 hours after surgery. Tramadol (3 mg/kg, PO, q 8 h) was administered to continue postoperative analgesia. The patient wagged its tail without obvious discomfort on the first day after surgery and was discharged from the hospital 2 days after surgery. A brief tail chewing episode occurred about 2 weeks after surgery. The dog was treated with amantadine, tramadol, and gabapentin for about 1 week, and the tail chewing behavior subsided and never returned. The dog was clinically normal 2 years after surgery.

Intervertebral disks are interposed in every intervertebral space (except between C1 and C2), uniting the bodies of the adjacent vertebrae.1 Degeneration can occur in all disks in the vertebral column. In chondro-dystrophic breeds, it can begin as early as 2 months of age and be complete by 1 year of age.2 Disk herniation most commonly occurs in the thoracolumbar vertebral column, causing upper motor neuron signs in the rear limbs.3 To the authors' knowledge, this is the first published report of disk herniation in the tail of a dog.

References

  • 1.

    Evans HE. Ligaments and joints of the vertebral column. In: Miller's anatomy of the dog. 3rd ed. Philadelphia: WB Saunders Co, 1993;229.

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  • 2.

    Añor S. Thoracolumbar/cervical disc disease in dogs. In Proceedings. World Small Anim Vet Assoc Cong 2002.

  • 3.

    Ruddle TLAllen DASchertel ER, et al. Outcome and prognostic factors in non-ambulatory Hansen type I intervertebral disc extrusions: 308 cases. Vet Comp Orthop Traumatol 2006; 19:2934.

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