According to current knowledge, the CDPA trait does not influence the risk of intervertebral disc herniation; from the Task Force’s perspective, the breeding of dogs with CDPA is therefore unproblematic from the point of view of intervertebral disc health.

When considering the breeding management of CDDY, it is important to distinguish whether scientific publications describe an increased incidence of intervertebral disc disease in the population in question. This is the case, for example, with the Dachshund breed, although it remains controversial to what extent the risk increases in the presence of one or two copies of the CDDY allele, and whether, in particular, the heterozygous presence of a single copy of the CDDY allele alone should already be regarded as a relevant risk indicator (Bruun et al., 2020, Sullivan et al., 2025). In any case, however, it should be noted that intervertebral disc disease is not a (monogenic) hereditary disease and therefore cannot be classified as such.

Furthermore, an immediate ban on breeding involving all carriers of the CDDY allele would, given the high allele frequency, have irreversible consequences for the breeding population and genetic diversity in numerous dog breeds; in many breeds, this would result in almost all dogs Furthermore, an immediate ban on breeding involving all carriers of the CDDY allele would, given the high allele frequency, have irreversible consequences for the breeding population and genetic diversity in numerous dog breeds; in many breeds, this would result in almost all dogs beingexcluded from breeding, even if they do not suffer from any associated health problems. Such a restriction of the existing breeding population and gene pool must be viewed in a highly critical light from various perspectives (e.g. restriction of existing genetic diversity).

Against this background, a complete exclusion from breeding of CDDY carriers solely on the basis of their CDDY genotype appears neither objectively justified nor expedient. A practically feasible and expedient alternative is an X-ray examination of the spine, as is already practised in various Northern European countries and also within the German Dachshund Club.

As scientific studies have shown that most calcifications become visible from the age of 24 months and may even partially regress thereafter, a radiological examination after the dog has reached two years of age to detect existing calcifications appears sensible and is accordingly already recommended in various publications (Jensen & Arnberg, 2001, Lappalainen, 2014, Reunanen et al., 2023).

In Denmark, a threshold of five calcified intervertebral discs has proven effective for excluding dachshunds from breeding. This threshold is based on study data which indicate that a significant increase in the risk of intervertebral disc herniation is to be expected from five calcified intervertebral discs onwards (Lappalainen et al., 2014), and breeding programmes based on this threshold have already led to a reduction in the number of calcified intervertebral discs in Dachshunds in Denmark. The members of the task force support such selection strategies.

If a reduction in the CDDY allele frequency is deemed appropriate, this should not be carried out too rapidly where the initial allele frequency is high, in order to preserve genetic diversity. In dachshunds, for example, the initial aim could be to breed for heterozygous animals, as these already have a reduced number of calcified intervertebral discs compared to homozygous animals (Sullivan et al., 2025).

The exact approach to managing the CDDY allele in different dog breeds should be determined by taking into account allele and genotype frequencies and the extent to which these are actually associated with health effects in the breed.

The use of the CDDY genetic test is advisable and can help to identify dogs with favourable genotypes that may be of interest for breeding. Particularly in dog breeds with CDDY allele frequencies >50%, no dog should be excluded from breeding solely on the basis of the CDDY genotype. In the event of selection against the CDDY allele, care must be taken to ensure that dogs with favourable CDDY genotypes are not used excessively in breeding, in order to preserve genetic diversity as much as possible.
Regardless of the results of veterinary examinations, animals that have suffered a herniated disc should under no circumstances be used for breeding. A suitable breeding programme aimed at reducing the incidence of disc disease should be in place for all breeds in which an increased prevalence of such conditions has been reported.