Search Results (3)

Background/Objectives: The fibroblast-growth-factor 4 retrogene insertion on chromosome 12 (FGF4L2) is known to be associated with chondrodystrophy and intervertebral disc disease (IVDD), which increases the risk of Hansen’s type I intervertebral disc extrusion (IVDE) in Dachshunds. While the FGF4L2 insertion is known to occur at high frequency within the breed, subgroup-specific data relating to coat-type and size categories remain limited. This pilot study aimed to determine the distribution of FGF4L2 and wild-type (N) alleles in a cohort of Dachshunds registered with the German Dachshund Club (DTK) and to evaluate differences among coat and size varieties. Methods: A total of 488 Dachshund samples from the DNA archive of the Deutscher Teckelklub 1888 e.V. (DTK) were analysed and genotyped. Genotype data was categorised according to coat-type and size variant. Allele and genotype frequencies were calculated for the overall population and for each subgroup. Results: The overall frequency of the FGF4L2 insertion allele was 96.51% (95% CI: 95.17–97.50). However, there were moderate differences between subgroups. The allele was nearly fixed in several coat and size variants. Standard wire-haired Dachshunds had the lowest allele frequency (89.09%) and were the only group in which homozygous wild-type individuals were observed. Heterozygous frequencies peaked in standard smooth-haired (16.7%) and standard wire-haired (14.5%) groups. Conclusions: Because the FGF4L2 frequency differs meaningfully between Dachshund varieties, grouping them into a single breed, as many studies do, can obscure the residual subgroup-specific genetic variation present in this population. Analysing the varieties separately provides a basis for future studies investigating factors that may interact with FGF4L2 in IVDE, thereby highlighting its multifactorial nature. It also reveals where wild-type alleles persist, making genotype-informed, variety-specific breeding a viable strategy for improving vertebral column health. However, variation in FGF4L2 allele frequency alone may not fully account for the recently reported differences in vertebral column health between Dachshund coat varieties. Full article

Cherry eye is the common name for prolapse of the nictitans gland, a tear-producing gland situated under the third eyelid of dogs. Cherry eye is characterized by a red fleshy protuberance in the corner of the eye, resembling a cherry. This protrusion is a displacement of the normal gland of the third eyelid, thought to be caused by a defect in the connective tissue that secures the gland in place. Options for treatment may include anti-inflammatory medications in mild cases, but surgical replacement of the gland is usually indicated. Cherry eye is most often seen in dogs under the age of two years, with certain breeds having a higher incidence, suggesting a potential genetic association. Integration of panel genetic testing into routine clinical practice allows for the generation of large numbers of genotyped individuals paired with clinical records and enables the investigation of common disorders using a genome-wide association study (GWAS) approach at scale. In this investigation, several thousand cases and controls for cherry eye in both purebred dogs and mixed breeds are used for a large-scale GWAS, revealing a single peak of genome-wide significance on canine chromosome 18, directly at the location of the previously identified FGF4 insertion known to cause chondrodysplasia in several breeds. Full article

Two FGF4 retrogenes (FGF4L1 on chromosome 18 and FGF4L2 on chromosome 12) have been identified to cause dwarfism across many dog breeds. Some breeds are nearly homozygous for both retrogenes (e.g., Dachshunds) and others are homozygous for just one (e.g., Beagles and Scottish Terriers). Since most breeds do not segregate both of these retrogenes, it is challenging to evaluate their individual effects on long bone length and body size. We identified two dog breeds selected for hunting ability, the Alpine Dachsbracke and the Schweizer Niederlaufhund, that segregate both of these retrogenes. Using individual measurements of height at the shoulder, back length, head width, thorax depth and width, and thoracic limb measurements, we evaluated the combined effects of FGF4 retrogenes within these breeds. We applied multivariable linear regression analysis to determine the effects of retrogene copy numbers on the measurements. Copy numbers of both retrogenes had significant effects reducing height at the shoulders and antebrachial length, with FGF4L1 having a much greater effect than FGF4L2. FGF4L1 alone influenced the degree of carpal valgus and FGF4L2 alone increased head width. Neither retrogene had an effect on thorax width or depth. Selectively breeding dogs with FGF4L1 and without FGF4L2 would likely lead to a reduction in the FGF4L2-related risk of intervertebral disc herniation while maintaining the reduction in leg length resulting from FGF4L1. Full article