Skeletal Manifestations of Heritable Disproportionate Dwarfism in Cats as Determined by Radiography and Magnetic Resonance Imaging

Abstract

Objective The aim of this study was to characterize the radiographic alignment of thoracic and pelvic limbs and evaluate for intervertebral disc disease in cats with feline disproportionate dwarfism (FDD). Study Design Observational cross-sectional study. Radiographic joint orientation angles were measured in 10 thoracic and pelvic limbs from 5 FDD cats and compared with those angles measured in 24 thoracic limbs and 100 pelvic limbs from skeletally normal cats. Magnetic resonance imaging of the spine was performed in 2 FDD cats for the evaluation of pathology of the intervertebral discs or vertebrae. Results All limbs from FDD cats possessed deformities. FDD humeri demonstrated procurvatum proximally, and recurvatum distally in the sagittal plane, but showed no difference in the frontal plane. FDD radii possessed excessive recurvatum proximally, and procurvatum distally in the sagittal plane, and varus proximally and valgus distally in the frontal plane. Whereas no torsion was discernible in the humeri, all radii had external torsion. In the frontal plane, FDD femurs exhibited varus both proximally and distally whereas the tibia possessed proximal valgus and distal varus. No torsion in the pelvic limbs was observed. No spinal pathology was detected in the FDD cats included in the original study. Conclusion Feline disproportionate dwarfism results in significant appendicular deformity in all limbs. The incidence of intervertebral disc degeneration in FDD cats is inconclusive.

Evaluation of the Radial Procurvatum Using the Center of Rotation of Angulation Methodology in Chondrodystrophic Dogs

“…In this study, Welsh Corgis and Dachshunds had the smallest values in CrPRA, CdDRA, and LDRA, and the second smallest values in MPRA, suggesting that the short leg length caused by the expression of FGF4RG induced a relatively small joint orientation angle. Similarly, in cats with disproportionate dwarfism, the joint orientation angles measured using the CORA methodology were confirmed to be smaller than those of normal cats ( 39 ). In addition, in this study, Pekingese showed the smallest values in MPRA compared with breeds, and the third smallest CdDRA and LDRA mean values after Dachshund and Welsh Corgi.…”

Bilateral ulnar retained cartilage cores causing thoracic angular limb deformities in a cat

“…Various other conditions can affect the physis, disrupting normal endochondral ossification, such as metaphyseal osteopathy 4 and physitis, 13 no features of which were present in this cat. Chondrodystrophy can also cause angular limb deformities in cats; however, this was not considered a differential diagnosis in this case due to the lack of disproportionate dwarfism, lack of generalised involvement, 14 imaging findings consistent with RCCs 1–6 and histological confirmation.…”