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General:
Laser disc ablation is a prophylactic procedure for thoracolumbar disc syndrome and is NOT meant to be used in place of a decompression of the spinal cord when a dog is severely paretic or weak, is paralyzed, or affected with acute signs of severe thoracolumbar pain. Over 300 dogs have undergone percutaneous disc ablation since the procedure was clinically introduced in 1993.
Eligibility Criteria:
1. Candidates are included in the OSU protocol when they have a history of TL disc disease but are recovered and virtually normal, neurologically. That means they do not have lumbar pain and walk normally. If a dog is presented at OSU with lumbar pain, and we concur with the referring veterinarian the dog does indeed have TL disc disease/problems, those animals still need to be treated conservatively (confinement only) for at least two weeks prior to disc ablation. We do that for two reasons: A) the holmium laser is a pulsed laser and could possibly push more material into the spinal canal during an acute episode (a physics problem), and B) we need to make certain the ablation procedure does not cause additional problems in the dog ‑ if it’s already painful when it is treated, we'll never know if the procedure has caused any additional problems with pain or other neurologic deficits.
2. Dogs to be included in this protocol must be held off and not administered oral or parenteral corticosteroids for a minimum of 2 weeks prior to admission for disc ablation. This precaution is to ensure inflammation or complicating neurologic signs (lumbar pain, proprioceptive deficits) are not masked or hidden prior to laser disc ablation.
Description of Procedure:
1. Dogs are given a pre-surgical evaluation, anesthetized, and aseptically prepared for laser disc ablation. The dorsolateral aspect of the left upper lumbar area extending from the caudal thoracic to the caudal lumbar spinal column is the site for percutaneous needle insertion.
2. Seven needles (20 gauge, 2 ½ " or 3 ½ “myelographic/spinal needles) are placed percutaneously into the center of 7 disc spaces (T10‑11 to L 3‑4). A fluoroscope is used to visualize placement of the needles.
3. A holmium:YAG (Ho:YAG) laser is used for vaporization of the nucleus pulposus by placing the laser fiber through the needle into the disc space at the level of the nucleus pulposus. The laser is activated and the disc material is vaporized/coagulated which removes / stabilizes the nucleus of the disc, in theory, so it no longer has a propensity to herniate in the future. We did document this effect over 12 years ago in trials using experimental animals.
Post-Operative Complications:
1. Immediate post ablation problems have been minimal. A few dogs have exhibited lumbar pain for 5 to 7 days, presumed to be of muscular origin from needle insertion. Depending on the immediate post-treatment exam, some animals are discharged with a short regime of an appropriate NSAID.
2. Acute complications have developed in 5 dogs. Two of these animals exhibited proprioceptive deficits immediately after disc ablation. They were treated medically and considered neurologically normal after 10 days of conservative medical therapy. One dog developed a small subcutaneous abscess that was responsive to local treatment and oral antibiotics. One dog required a decompressive hemilaminectomy within one week of laser disc ablation, presumably due to additional disc material being photomechanically pushed by the Ho:YAG laser into the vertebral canal. Finally, one animal exhibited no clinical signs, but was radiographically documented to have pneumothorax with a minimal amount of air evident in the thoracic cavity. This problem alleviated itself without clinical intervention. (NOTE: For disc ablation procedures, radiographs are taken to document needle placement in all cases.)
3. One laser disc ablation case (a cocker spaniel) developed diskospondylitis in two of seven ablated IV disc spaces. It responded to oral antibiotics and a non‑steroidal anti‑inflammatory. This dog had a history of both a recurrent ear infection and chronic dermatitis. Because of that particular case, the protocol was slightly altered for animals with histories of chronic skin/ear problems. A prophylactic dose of antibiotics is intravenously administered prior to laser disc ablation in these dogs.
4. Nine dogs (3.4%) have had a recurrence of paraparesis/paralysis requiring surgical intervention (decompressive hemilaminectomy). All animals recovered uneventfully after appropriate treatment. (NOTE: This result indicates that laser disc ablation is certainly not a guaranteed procedure since laser tissue interaction involving degenerative intervertebral discs can’t be predicted 100% nor can the total success of interventional needle placement within the discs themselves.
General Comments:
Laser disc ablation is still somewhat controversial in some veterinary surgeon's eyes due to the fact not all surgeons believe in prophylactic fenestration of the thoracolumbar IV discs ‑ they may treat their cases medically until the dog needs decompression due to severe protrusion/extrusion of a disc that puts pressure on the spinal cord, or they may perform the decompression immediately, depending on the severity of signs. Some of the acute/severe herniations, however, are very "catastrophic" and animals don't recover, as you well know. Although we have had 8 recurrences from over 300 animals that have undergone the procedure so far, those dogs still recovered – we feel the procedure has been of benefit since, conceptually, we potentially reduce the amount of disc material that could herniated or extrude without disc ablation.
An article written in the Journal of the American Veterinary Medical Association and published April 15, 1996, (Dickey, Bartels, et al), provides the criteria for the protocol as well as a report of 32 dogs.
In another peer-reviewed article, we have documented 262 cases with follow-up evaluations and that investigation has been published in JAVMA:
Reference: Bartels, K.E., Higbee, R.G., Bahr, R.J., Galloway, D.S., Healey, T.S., Arnold, C.S., Outcome of and Complications Associated with Prophylactic Percutaneous Laser Disk Ablation in Dogs with Thoracolumbar Disk Disease: 277 cases (1992-2001), JAVMA, Vol. 222 (12): 1733-1739, June 15, 2003.
We are also in the process of evaluating our results in comparison to other studies in the following situations: 1) dogs treated by medical techniques alone (rest, steroids, anti-inflammatory drugs); and 2) dogs treated with decompression, when severely affected, and then having recurring episodes at other sites.
Laser Disc Protocol:
1. We are constantly reviewing this procedure and emphasize the fact it is a prophylactic procedure to "informed consent" clients.
2. The procedure costs approximately $1500 at this point in time. It is still being "underwritten" by research funds since the laser technology is expensive As with every medical procedure, the cost may have to go up a bit, but I hope it will always be possible to provide the service for a reasonable fee.
3. If accepted for the procedure, dogs are admitted on day 1 and given a complete physical examination. Pre-anesthetic blood work is performed, and then on day 2 the procedure is performed. In most instances, the dog is discharged on day 3.
4. Currently, we do not offer the procedure to dogs that have NOT had a history of back problems ‑ to be included they must have had a history of problems (back pain attributable to IV discs / or a previous TL surgery). We also do not offer the procedure for cervical disc disease at this time.
Conclusion:
I am pleased there is interest in the procedure. We feel it works well and decreases the morbidity seen from previous surgical fenestration procedures. AGAIN, this does not take the place of decompression when that is needed for severe problems due to a herniated thoracolumbar disc. The best person to determine if laser disc ablation is a potential procedure for a dog is a referring veterinarian with the ability to perform a good neurologic exam. Clinicians at OSU can assist with making the best decision for each individual case. To be considered for this protocol, please discuss the case / situation with a member of the Small Animal Surgery faculty.
Kenneth E. Bartels, DVM, MS
McCasland Professor of Laser Surgery
Cohn Chair for Animal Care
Veterinary Clinical Sciences (405-744-6731)
Center for Veterinary Health Sciences
Oklahoma State University
Stillwater, Oklahoma 74078
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