IVDD X-ray screening - UK evidence that it works

We've recently completed an analysis of the UK IVDD Screening Programme's results. There's a full report (PDF) here. This report presents the analysis of UK data to answer the question: Are dogs with 5 or more calcifications more likely to have clinical signs of Intervertebral Disc Disease (IVDD)?

The answer is "yes". The screening programme grades dogs from 0 to 3, with Grade 0 dogs having no calcified discs and Grade 3 dogs having 5 or more calcified discs. Previous research has shown that the number of calcified discs, assessed between 24 and 48 months, is a good predictor of disc herniation.

Using the full set of survey data (all ages) the Odds Ratio for an IVDD case in Grade 3 dogs is 2; i.e. twice as likely than dogs with Grade 0-2. However, this is not statistically significant.

Since we might expect some of the younger dogs in the survey to have not yet suffered an IVDD incident, it is worth examining a subset of the data, for the older dogs. Taking only those dogs aged 7 or older gives an Odds Ratio of 12; i.e. dogs aged 7 or older with a screening Grade 3 result were 12 times more likely to have had an IVDD incident than dogs with Grades 0, 1 or 2. Although this is a smaller sample of dogs, it is statistically significant (P=0.03; 95% CI 1.2-120).

Whether we look at the full set of data or the sample of older dogs, it is clear that dogs with low numbers of calcifications are less likely to suffer an IVDD incident. Our results are consistent with the Nordic data published in numerous studies. The X-ray screening results also help to explain that the test is an assessment of risk. Some dogs with good scores (low calcifications) may still end up with a herniated disc but, on the balance of probability, they are less likely to do so than dogs with high numbers of calcifications.

Currently, we have insufficient data to be able to draw any conclusions about the long-term effectiveness of the screening programme in reducing IVDD. We need more dogs to participate in the programme and we need to see the results of subsequent generations of offspring. The evidence from previous research is that dogs with low calcifications produce offspring with low calcifications.

Dachshund Health UK and the Royal Kennel Club are currently subsidising the screening programme. If you would like to make a donation towards our continuing research and education programmes, you can do so here.