Ultyrasonographic guided fine needle aspiration of intervertebral disc in dogs

The current diagnostic work up of discospondylitis is routinely based on blood and urine culture, but culture from affected discs seems to be more sensitive (90%) than from blood and urine (65%). Surgical or percutaneous sampling techniques were well described and the purpose of this preliminary study is to assess the feasibility of ultrasonographic fine needle aspiration (UFNA) of the intervertebral disc (ID) in dogs. UFNA was randomly performed in 9 euthanasized dogs. The investigation was limited to the thoracolumbar junction and lumbar tract (L2-L6) with two different approaches: dorsolateral and ventrolateral.22 UFNA with a ventrolateral approach and 7 with dorsolateral were performed. the procedure was made immediately after euthanasia to avoid any post mortem anatomical change. All dogs wer placed in left lateral recumbency ; after detection by palpation of the right tranverse vertebral process, a 7.5 MHz tranducer was positioned close to the lumbar vertebra. After ultrasonographic identification of the vertebral bodies and of the intervetebral space (IS) a 22 G spinal needle was freehand inserted with a 30° angle to the transducer longitudinal axis to reache the IS. In all cases plain radiographs were taken both in lateral and dorsoventral views. Then a complete anatomical dissection was made in all dogs to evaluate the final position of the bevel and a standard cytologic examination of the aspiration sample was achieved. When correct identification of IS was ultrasonographically achieved (18/29) the ventrolateral approache led to a correct needle positioning in 80% (12/15) of cases and the percentage rose up to 100% (3/3) in case of dorsolateral approach.In conclusion the method seems to be a reliable and unexpensive technique for ID sampling. The clinical application needs to be further investigated and could represent an easy and mininvasive techique for ethiological diagnosis of discospondylitis