The invention provides an in vitro method or assay for the diagnosis of osteochondrosis or prediction of the likelihood of its onset in a terrestrian mammal, comprising measuring the expression level of a marker in a sample obtained from said terrestrian mammal and comparing said expression level to the expression level of said marker measured in a sample obtained from one or more terrestrian mammals of the same species not affected by osteochondrosis, wherein the marker is ApoB-3G, and wherein an increase in the expression level of ApoB-3G is indicative of osteochondrosis. The invention also provides a diagnostic kit for use in said method, which comprises at least one agent, which binds specifically to the product of the gene of the respective marker and which can be used to determine the expression level of said marker, wherein the marker is ApoB-3G.