Intervertebral Disc Disease

What is known about the genetics behind IVDD?

An over-expressing FGF4 retrogene on CFA12 (named 12-FGF4RG and also referred to as Chondrodystrophy (CDDY)) has been unequivocally identified as a genetic risk factor for IVDD in chondrodystrophic breeds as well as being associated with short legs (Brown, E.A. et al.) and this variant forms the basis of genetic screening tools available globally. Reducing 12-FGF4RG allele frequency clearly has the potential to lower IVDD incidence but for breeds where 12-FGF4RG frequency is very high/fixed this is not an option. For these breeds, the successful reduction of IVDD incidence will rely on identifying as many additional risk factors as possible.

Despite sharing the FGF4RG risk factor, there are quite big differences in the IVDD disease process between different chondrodystrophic breeds, including disease incidence, the typical age when IVDD occurs and the location in the spine of affected discs. For this reason we believe that additional genetic and/or environmental/lifestyle risk factors must be involved and that these might well represent be a better way of reducing the risk of IVDD than screening for 12-FGF4RG, for some breeds.

Are there other risk factors that lead to IVDD?

Intervertebral disc disease (IVDD) is the most common cause of spinal injury in dogs with clinical signs ranging from pain to complete, irreversible paralysis of the limbs. IVDD can affect all breeds but chondrodystrophic (short-legged) breeds are at highest risk, which is a significant concern given their popularity.

Simply put, IVDD refers to the process whereby the spongy, cushioning discs that sit between the vertebrae lose their ‘sponginess’. When this happens the discs can bulge or even burst into the space between the vertebrae that contains the spinal cord. When the disc material pushes on the spinal cord, it can cause pain, nerve damage, and even paralysis.

Our current work investigating IVDD

Dachshunds are overrepresented in most reports of IVDD, with about 15% of all Dachshunds likely to develop IVDD during their lifetimes (Packer. R.M. et al., Wee, C. & Nin, D. et al.). For this reason our investigations are currently focused on Dachshunds although we have also recently reported on lifestyle and conformation risk factors for IVDD in Cocker Spaniels (paper accepted for publication). In time, and with appropriate funding, we hope to extend our investigations into other breeds, some of which might benefit directly from our findings in Dachshunds.