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Abstract

OBJECTIVE

Compare 3 methods of nucleus pulposus (NP) volume measurement using the rabbit lumbar spines as a preclinical model to determine the effectiveness of prophylactic intervertebral disk fenestration in dogs.

ANIMALS

Twelve 9-month-old, skeletally mature female entire New Zealand White rabbits weighing between 3.5 to 4.5 kg.

METHODS

NP volume measurements of dissected rabbit lumber spines between L1 and L6 were made and compared using gross measurements, reconstructed MRI images, and water volumetry based on Archimedes’ principle. Water volumetry was used as the true gold standard volume measurement in this study.

RESULTS

The true volume (mean ± SD) of the nucleus pulposus NP as measured by water volumetry increased caudally from L1/L2 (16.26 ± 3.32 mm3) to L5/L6 (22.73 ± 6.09 mm3). Volume estimates made by MRI were significantly higher than those made using water volumetry at all sites (L1/L2 [P = .044], L2/L3 [P = .012], L3/L4 [P = .015], L4/L5 [P < .001], and L5/L6 [P < .001]). Gross measurements also significantly overestimated volume when compared to water volumetry at all sites; L1/L2 (P = .021), L2/L3 (P = .025), L3/L4 (P = .001), L4/L5 (P < .001), and L5/L6 (P < .001). MRI and gross volume estimates were significantly different at L4/L5 (P = .035) and L5/L6 (P = .030).

CLINICAL RELEVANCE

The findings of this preclinical model might be relevant to veterinary surgeons who perform prophylactic fenestration for which there is no reliable method to determine the amount of NP to be removed. Preclinical ex vivo and in vivo fenestration studies with pre- and postoperative NP volume assessment are required.

Open access
in American Journal of Veterinary Research

Abstract

Case Description—3 horses were examined and treated because of sudden onset of signs of abdominal pain.

Clinical Findings—All horses had a retrosternal (Morgagni) hernia involving the right side of the diaphragm. In each horse, the large colon was incarcerated in a right muscular defect in the diaphragm with a large hernial sac.

Treatment and Outcome—Definitive surgical repair of the hernia was not performed during the initial celiotomy. The hernia was repaired with mesh herniorrhaphy, but without resection of the hernia sac in 2 horses. For 1 horse, conservative management was applied. In the 2 horses treated with surgical correction, no major postoperative complications developed, and all 3 horses have been free of signs of abdominal pain.

Clinical Relevance—Horses with retrosternal hernias involving the diaphragm can develop clinical signs of intermittent obstruction of the large colon and chronic colic. In horses, retrosternal diaphragmatic hernias appear to develop exclusively in the right ventral aspect of the diaphragm and could represent an embryologic defect of diaphragm formation. Affected horses can be successfully treated with mesh herniorrhaphy or, in some instances, with conservative management.

Full access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association