Radiographic Morphometry of the Lumbar Spine in Munich Miniature Pigs.

The incidence of human spinal column disease remains high, and animal models still play important roles in prophylactic, diagnostic, and therapeutic research. Because of their similar size to humans, pigs remain an important spine model. For pigs to serve as a model for the human spine, basic similarities and differences must be understood. In this study, morphometric data of the lumbar spine of Munich miniature pigs (Troll) were recorded radiologically, evaluated, and compared with recorded human data. Whereas humans have a constant number of 5 lumbar vertebrae, Munich minipigs had 5 or 6 lumbar vertebrae. Compared with their human counterparts, the lumbar vertebral bodies of the minipigs were remarkably larger in the craniocaudal (superior-inferior) direction and considerably smaller in the dorsoventral and laterolateral directions. The porcine vertebral canal was smaller than the human vertebral canal. The spinal cord extended into the caudal part of the porcine lumbar vertebral canal and thus did not terminate as cranial, as seen in humans. The lumbar intervertebral spaces of the pig were narrower in craniocaudal direction than human intervertebral spaces. These differences need to be considered when planning surgical actions, not only to avoid pain and irreversible damage to the minipigs but also to achieve accurate scientific results.

Cartilage thickness of the trochlea of the talus, with emphasis on sites predisposed to osteochondrosis dissecans, in clinically normal juvenile and adult dogs.

OBJECTIVE: To evaluate cartilage thickness of the talus (especially at sites predisposed to osteochondrosis dissecans [OCD]) in growing and adult dogs not affected with OCD. SAMPLE: Tarsocrural joints from cadavers of 34 juvenile (approx 3 months old) and 10 adult dogs. PROCEDURES: Tarsal cartilage thickness was examined via a stereophotography microscopic system. Articular cartilage thickness was determined at 11 locations on longitudinal slices of the trochlear ridges and the sulcus between the ridges and at 2 locations in the cochlea tibiae. Cartilage thickness was measured at the proximal, proximodorsal, dorsal, and distal aspects of the trochlear ridges; proximodorsal, dorsal, and distal aspects of the trochlear sulcus; and craniolateral and caudomedial aspects of the cochlea tibiae. Differences within a joint and between sexes were evaluated. RESULTS: Mean cartilage thickness decreased from proximal to distal in juvenile (lateral trochlear ridge, 1.52 to 0.41 mm; medial trochlear ridge, 1.10 to 0.40 mm) and from proximal to dorsal in adult (lateral trochlear ridge, 0.41 to 0.34 mm; medial trochlear ridge, 0.33 to 0.23 mm) dogs. Cartilage was thickest at the proximal aspect of the lateral trochlear ridge in both groups. Differences in proximodorsal, dorsal, and distal aspects of the ridges were not evident. CONCLUSIONS AND CLINICAL RELEVANCE: Healthy tarsocrural joints did not have thicker cartilage in sites predisposed to development of OCD. Evaluation of affected tarsocrural joints is necessary to exclude influences of cartilage thickness. These data are useful as a reference for distribution of cartilage thickness of the trochlea of the talus in dogs.