Familial chondrodysplasia in Holstein calves.

After the release of a report from France on the occurrence of malformed calves genetically related to a Holstein sire, a study was performed to characterize the defect. Danish breeders were encouraged to submit defective progeny of the sire for laboratory examination. Four cases were submitted, whereas a fifth case was only reported. Lesions in affected calves were analogous, with disproportionate growth retardation characterized by fascial dysplasia and shortening of the vertebral column and the abaxial skeleton. Endochondral osteogenesis was disturbed with disorganization of epiphyseal plate chondrocytes, a lesion consistent with generalized chondrodysplasia. Based on morphology, the defect was grouped as a "Dexter bulldog type". A genetic etiology was suspected as cases occurred in a familial pattern. Genealogical evaluation revealed several common ancestors belonging to widely used breeding lines of US Holstein, but because of the extensive use of these sires, their presence in the pedigrees of affected calves might be accidental. Further studies are needed to determine the mode of inheritance.