A variety of inherited osteochondrodysplasias causing disturbances in cartilage and bone growth and development have been identified in humans. Some of these conditions have also been identified in dogs, and in some specific breeds, these conditions are considered normal characteristics. As an example, achondroplasia is considered a normal characteristic in Bulldogs, Boston Terriers, and Pekingese, and hypochondroplasia is considered a normal characteristic in Dachshunds and Beagles.1 In addition, certain infectious diseases, toxins, dietary deficiencies, and hormonal deficiencies may cause bone lesions similar to those seen with inherited osteochondrodysplasias.1
One of the less well known of the osteochondrodysplasias in dogs is MED. In 1956, Cotchin and Duce2 reported a single case of epiphyseal dysplasia involving a male Miniature Poodle, and other authors reported 3 similar cases over the next 10 years.3,4 In a report of MED involving a litter of Beagles, Rasmussen5 indicated that 4 of the 8 puppies in the litter had delayed bone formation in the epiphyses with stippled or punctate calcification.
Rasmussen and Reiman6 later bred 2 of the affected dogs from this litter, resulting in 5 diseased puppies, suggesting that the condition had an autosomal recessive mode of inheritance. Johnson et al7 reported a case of MED involving a Golden Retriever mixed-breed dog that had severe clinical signs and in which radiography of the epiphyses of the humeral and femoral heads and the vertebrae revealed severely delayed bone formation. Saunders and Jezyk8 reported on a litter of dogs with similar-appearing lesions that had congenital hypothyroidism.
Because of the limited number of cases of MED in dogs that have been published, more information is needed on this condition. The purpose of the study reported here, therefore, was to determine clinical, radiographic, and pathologic abnormalities in dogs with MED.
Multiple epiphyseal dysplasia
Immulite 2000, Diagnostics Product Corp, Roche Norway, Oslo, Norway.
Jezyk PF. Constitutional disorders of the skeleton in dogs and cats. In: Newton CD, Nunamaker DM, eds. Textbook of small animal orthopaedics. Philadelphia: JB Lippincott Co, 1985;643–645.
Rasmussen PG. Multiple epiphyseal dysplasia in a litter of Beagle puppies. J Small Anim Pract 1971;12:91–97.
Rasmussen PG, Reiman I. Multiple epiphyseal dysplasia, with special reference to histological findings. Acta Pathol Microbiol Scand [A] 1973;81:381–389.
Johnson RP, Fitch RB, Oliver J, et al. What is your diagnosis? Multiple epiphyseal dysplasia of the femoral head, proximal humerus and vertebral end plates. J Am Vet Med Assoc 1998;212:1699–1700.
Saunders MH, Jezyk PK. The radiographic appearance of canine congenital hypothyroidism: skeletal changes with delayed treatment. Vet Radiol 1991;32:171–177.
Briggs MD, Chapman KL. Pseudoachondroplasia and multiple epiphyseal dysplasia: mutation review, molecular interactions, and genotype to phenotype correlations. Hum Mutat 2002;19:465–478.
Briggs MD, Hoffman SMG, King LM, et al. Pseudoachondroplasia and multiple epiphyseal dysplasia due to mutation in the cartilage oligometric matrix protein gene. Nat Genet 1995;10:330–336.
Unger S, Hecht JT. Pseudoachondroplasia and multiple epiphyseal dysplasia: new etiologic developments. Am J Med Genet 2001;106:244–250.
Jakkula E, Makitie O, Czarny-Ratacjzak M, et al. Mutations in the known genes are not the major cause of MED; distinctive phenotypic entities among patients with no identified mutations. Eur J Hum Genet 2005;13:292–301.
Ballhausen D, Bonafé L, Terhal P, et al. Recessive multiple epiphyseal dysplasia (rMED): phenotype delineation in eighteen homozygotes for DTDST mutation R279W. J Med Genet 2003;40:65–71.
Eyre S, Roby P, Wolstencroft K, et al. Identification of locus for a form of spondyloepiphyseal dysplasia on chromosome 15q26.1: exclusion of aggrecan as a candidate gene. J Med Genet 2002;39:634–638.