Genetics of degenerative suspensory ligament disease (DSLD)
in the horse
June 24th, 2019
Breed(s): The Peruvian Horse and other breeds affected with DSLD
Study Type: DNA samples and ligament tissue samples
Study Location: University of Wisconsin-Madison
Degenerative suspensory ligament disease (DSLD) is an equine disease that is being recognized more frequently. Disease onset is subtle in affected horses often with no history of injury and usually affects more than one limb. DSLD has been diagnosed in multiple breeds such as the Peruvian Horse, the Paso Fino, Warmblood breeds, Thoroughbred, Standardbred, American Quarter Horse, Arabian, American Saddlebred, and Akhal-Teke.
The cause of DSLD is not fully understood and injuries to the suspensory ligament sometimes get misdiagnosed as DSLD. Therefore, further research into DSLD is necessary. Data from the Comparative Genetics Laboratory at the University of Wisconsin-Madison suggest that DSLD in the Peruvian Horse is most likely a recessive Mendelian genetic disease, meaning that there is a simple mode of inheritance where horses with two copies of the mutated gene develop the disease and horses with only one copy if the mutation are carriers of the disease and are healthy clinically. We are studying the Peruvian Horse for this work because support from the breed organization and strong engagement with this project by the community of horse owners.
Since DSLD is very similar to degenerative tendon ruptures in human beings, we have been able to obtain funding from the National Institutes of Health for a One Health study aimed at discovering the genetic basis of DSLD in the horse and then examining human tendinopathy patients to determine whether mutation of the same gene may cause degenerative tendinopathy in human patients. General understanding of the genetics of DSLD in horses is limited. Our work will advance discovery of the causal genetic variant(s) for DSLD. This will not only advance genetic testing for the disease and medical treatment for affected horses but will also inform understanding of human tendon injury. We are working with the North American Peruvian Horse Association
Cases must be purebred Peruvian Horses that have DSLD. We also wish to study purebred horses of other breeds with DSLD. Unaffected control horses must be purebred Peruvian Horses over the age of 14 years with no history of DSLD or other suspensory ligament problems.
Owner’s Responsibilities (Samples and Information to be collected):
All horses will be recruited with signed consent from their owners. A copy of the pedigree will be collected from each horse recruited to the study. All horses will have a blood sample drawn (preferred) or hair bulbs pulled from the mane or tail for DNA isolation and genome-wide genotyping or whole genome sequencing. Whole genome sequencing will include assembly and a breed-specific Peruvian Horse genome sequence to complement the reference genome which is based on a Thoroughbred horse. If an owner chooses to donate a case or control Peruvian Horse or a DSLD case of another breed to the School of Veterinary Medicine, ligament tissue samples will be collected for RNA isolation and RNA sequencing. For cases we request photographs of the horse, information from clinical examination and ultrasound imaging used for diagnosis. For unaffected controls, physical exam findings and ultrasound imaging, if used for screening, must confirm absence of DSLD. Horse age, sex, and disease severity will also be recorded, and the owner will complete a questionnaire that will be used to assess habitual activity.
Names: Dr. Sabrina Brounts, Dr. Peter Muir
Facebook: Comparative Genetics Laboratory at UW School of Veterinary Medicine