Degenerative lumbosacral stenosis in dogs - Veterinary Medicine
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Degenerative lumbosacral stenosis in dogs
You may not readily recognize degenerative lumbosacral disease in your large-breed patients because they commonly have other concurrent orthopedic diseases. Here's how to identify affected dogs and help them with the right therapy.


VETERINARY MEDICINE


TREATMENT

Treatment options for degenerative lumbosacral stenosis can be divided into medical and surgical therapy.

Medical therapy

Medical therapy consists of exercise restriction and administering anti-inflammatory agents.8,12,21 Institute exercise restriction (the patient is confined and allowed out only with controlled leash walking) for a minimum of four to six weeks. Then institute a gradual return to exercise over an additional four to six weeks.

During this period, anti-inflammatory medications can be used to reduce pain. In mild cases, such as dogs with only hyperesthesia or minimum neurologic deficits, you can try nonsteroidal anti-inflammatory drugs (NSAIDs). Any of the available NSAIDs can be used at standard dosages. A specific duration of therapy is not known, but four to six weeks may be needed. In dogs with more severe neurologic deficits, you can use corticosteroids at anti-inflammatory dosages (e.g. prednisone at 0.5 to 1 mg/kg/day). The doses should be tapered over two to four weeks. Use caution when administering corticosteroids because serious side effects can include gastrointestinal ulceration, increased thirst and appetite, and muscle atrophy and weakness. Concurrent treatment with NSAIDs and corticosteroids is contraindicated.

The efficacy of medical management is variable.8,12,21 Dogs with more severe neurologic deficits or dogs that have a progressive decline in function or persistent pain in spite of medical therapy are more likely to benefit from surgical intervention.

Surgical treatment

Various surgical techniques have been used to treat degenerative lumbosacral stenosis, including dorsal laminectomy, dorsal laminectomy and diskectomy, and dorsal laminectomy and subsequent stabilization.37

Briefly, the patient is positioned in dorsal recumbency, and a dorsal midline incision is made from approximately L5 through the sacrum. The overlying epaxial musculature, which includes the multifidus lumborum and sacrocaudalis medialis dorsalis, is dissected down the midline. The L7 sacral articulation is exposed. A pneumatic drill is used to remove the dorsal lamina from the caudal aspect of the L7 vertebra through the cranial aspect of the sacrum. The interarcuate ligament is carefully removed with the dorsal lamina, exposing the epidural fat and nerve roots. The lateral borders of the laminectomy are bounded by the medial aspect of the L7-sacral articular processes. Overzealous removal of pedicles laterally can result in subluxation.

At this point, diskectomy is performed by gently retracting the exposed nerve roots laterally across the midline. A No. 65 Beaver blade or No. 11 Bard Parker scalpel is used to remove the exposed half of the dorsal longitudinal ligament and dorsal aspect of the anulus fibrosus and nucleus pulposus. Further curettage of the intervertebral disk can be performed with bone curettes. Once curettage is completed, the nerve roots are retracted to the other side, and the procedure is repeated. Before closure, subcutaneous fat is harvested and placed over the laminectomy.

Internal fixation can be combined with dorsal decompression, but this requires technical expertise with orthopedic implants. Once decompression has been achieved, internal fixation can be accomplished by placing cortical bone screws across the L7-sacrum articular processes and into the body of the sacrum.

As with any surgical procedure, postoperative care is important. Most commonly, analgesia is provided with opioid analgesics. Supportive care with intravenous fluid therapy should be provided until the patient begins eating and drinking. If the patient cannot voluntarily urinate, it is important to prevent overdistention of the urinary bladder. This can be accomplished with manual expression, intermittent sterile catheterization, or a sterile closed urinary collection system. Patients can walk slowly on a leash after surgery; however, depending on an animal's need, additional hindquarters support should be provided. Various commercially available sling supports or a towel placed under the caudal abdomen can help a patient when walking. Soft bedding and frequent repositioning help prevent the development of pressure sores.

PROGNOSIS AND OUTCOME

The long-term successful outcome of dogs undergoing surgical interventions for degenerative lumbosacral stenosis range between 69% and 94%.12,28,38-41 Likely part of the variability in the number of successful outcomes results from applying different definitions of success.38 There seem to be few preoperative prognostic indicators for return of function postoperatively. In some studies, most dogs with clinical signs limited to pain had successful outcomes.28,40 While information is available on only a small number of patients, resolution of incontinence ranges from 13% to 45% of cases.12,28,38 In one study, dogs with incontinence for less than one month had a greater likelihood of regaining continence postoperatively.38


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Source: VETERINARY MEDICINE,
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