Intervertebral Disc Degeneration (IVDD)
Herniation of the intervertebral disc (a “slipped disc”) is a significant problem in dogs and a common cause of pain and difficulty walking. Although dogs of any breed can be affected Dachshunds are 10–12 times more likely to suffer than other breeds, indicating the disorder probably has a genetic component and mutations in specific gene(s) play a role in the development of the condition.
We are embarking on a study to investigate the genetics of IVDD in Dachshunds, with the aim of developing a genetics tool that breeders can use to reduce the prevalence of the disease.
For our study we need DNA from:
- Cases - Dachshunds, of any variety, that have been diagnosed with disc herniation by a veterinary neurologist. Please provide a copy of the MRI or other relevant reports.
- Controls - Dachshunds, of any variety, that are over the age of 10 and have NO history of back and/or neck pain.
If your Dachshund qualifies as either a case or a control please contact us to discuss donating a DNA sample to contribute to this important research study.
The process we use to investigate an inherited disease is more or less the same, regardless of the disease, and always starts with sample collection. To study any disease we require DNA samples from dogs that are affected with the disease (we call these ‘cases’) and also dogs of the same breed that are unaffected (we call these ‘controls’). We will usually ask for written confirmation that a dog is affected, such as a letter from the dog’s vet or a copy of his/her eye examination report. For some diseases we will also need confirmation that the controls are truly clear of disease, such as a clear eye examination report, although for some conditions it will be sufficient for the owner to tell us the dog is not affected (e.g. epilepsy). The number of cases and controls that we need samples from varies between diseases, and depends on several factors such as the mode of inheritance and the number of genes that are likely to be involved, but is usually between 24 and 100. Recent advances in technology, specifically whole genome sequencing (WGS), have made it possible to investigate certain diseases with a very small number of cases.
We can collect and store DNA samples indefinitely, until we have enough to start the active research. Once we have samples from enough dogs, we analyse their DNA with about 170,000 different markers located along the DNA, to hopefully identify regions of the DNA that are similar in the cases and different in the controls; such a region is very likely to harbour the causal mutation. The dog’s genome consists of around two and a half thousand million (2.5 x 109) nucleotides of DNA. If each nucleotide was 1mm long the canine genome would stretch from Land’s End to John O’Groats and back again. A mutation that is responsible for an inherited disease can be anywhere in the DNA and can be as small as a single incorrect nucleotide, so pinpointing a disease-associated mutation can be quite a challenge. Once we have identified a region (called the ‘critical region’) of the DNA that contains a mutation (equivalent to a one or two mile stretch of road on the journey from Land’s End to John O’Groats and back) we ‘zoom in’ on that region and sequence some or all of the DNA within the region, nucleotide by nucleotide, until we identify the mutation that is causing the disease we are investigating. Once we have identified the mutation and confirmed we have the correct mutation, by analysing the DNA from a large number of cases and controls, we develop a DNA test that is offered to the public by our DNA testing facility.
Most of our staff in the Canine Genetics team are currently funded by the Kennel Club Genetics Centre at the AHT but we still need to raise funds to pay for the laboratory materials we use during the active research phase of each investigation. We routinely apply to funding bodies such as the Kennel Club Charitable Trust and the American Kennel Club Canine Health Foundation; in addition much of our funding comes from Breed Clubs and also from generous donations from individuals.