Chondrodysplastic puppies, up to twelve weeks of age, are readily identifiable by radiographs of the carpal joint. Although all endochondral bones in the chondrodysplastic animal are affected, the condition is most apparent at the distal end of the ulna. In a normal puppy the distal metaphysis of the ulna appears V-shaped and evenly opaque, consistent with normal ossification and development.
In the chondrodysplastic puppy, the distal metaphysis of the ulna is distinctly flattened and irregular, with a blunt widening of the distal diaphysis. There is variable evidence of normal ossification. The physis is increased in width with an irregular metaphyseal margin. [reference 2]
After twelve weeks of age the joint begins to change. Some adult chondrodysplastics radiographically display relatively normal ossification. Therefore radiographs should not be assumed as a definitive diagnosis after twelve weeks of age. Radiographic evidence is most consistent between five and twelve weeks of age. [reference 2]
Radiographs of chondrodysplastic and normal animals have been placed on separate pages. You can click on the thumbnail images below to view them in much more detail.
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It is important to note that the sloping topline of many chondrodysplastic animals is a manifestation of alteration in conformation of the limbs and is not related to changes in the axial skeleton. The varying degree of topline slope is a direct result of the malformation which develops in the front limbs. The tubular bones at the distal radius and ulna are the most severely affected and growth retardation is excessive. The bones of the hind limbs are much less severely affected and achieve a more normal conformation. Some chondrodysplastic animals may display near normal conformation. Diagnosis of genotype in such cases must then be made by either test-mating the animal or by blood work. [reference 3]
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Copyright © 1999 Linda Dowdy, last revision 991020