Silent but Serious: Incidental Aortic Dissection Linked to Genetic Variants in a Young Dog

Incidentally Identified Aortic Dissection in a Great Pyrenees Dog

H. Melhorn; M. Sha; M. Kurihara; K. Megquier; R. Aronson; V. Yang

Background

Aortic dissection (AD) is a rare and potentially fatal vascular condition in veterinary medicine, most often associated with systemic hypertension, trauma, or connective tissue disorders. Diagnosis in dogs is typically made postmortem or following acute clinical deterioration, and incidental detection is uncommon. This case report describes an incidentally identified ascending aortic dissection in a young Great Pyrenees dog and explores advanced imaging and genetic testing as tools to clarify diagnosis and underlying etiology.

Methods

A two-year-old female spayed Great Pyrenees underwent follow-up transthoracic echocardiography after previously documented dilation of the aortic root and ascending aorta. Additional diagnostic imaging included transesophageal echocardiography (TEE) and cardiac magnetic resonance imaging (MRI). Given the absence of systemic hypertension or other identifiable inciting causes, whole-genome sequencing was performed using a buccal swab to evaluate for variants associated with connective tissue disorders. Variant calling and annotation were performed using established bioinformatics pipelines and compared against a large canine reference genome dataset.

Results

Transthoracic and transesophageal echocardiography identified a thin intraluminal membrane within the ascending aorta, suspicious for aortic dissection, though the full extent was not clearly visualized. Cardiac MRI confirmed a Stanford type A aortic dissection, demonstrating a hypointense linear structure within the ascending aortic lumen with an associated false lumen extending toward the brachiocephalic trunk. Genetic sequencing identified high-impact variants in three genes associated with connective tissue integrity—SMAD4, ADAMTS3, and ADAMTSL2—all of which have known associations with aortic aneurysm or dissection in humans. The dog remained subclinical and was managed medically with carvedilol and exercise restriction, with reported clinical stability.

Limitations

As a single case report, causal relationships between identified genetic variants and the development of aortic dissection cannot be definitively established. Functional validation of the detected variants was not performed, and long-term outcome data are limited. The rarity of the condition restricts generalization to broader canine populations.

Conclusions

This case highlights the potential for incidental identification of clinically silent aortic dissection in dogs and demonstrates the complementary role of cardiac MRI when echocardiography is inconclusive. The detection of multiple genetic variants associated with connective tissue disorders suggests a possible inherited predisposition in this patient. Advanced imaging combined with genetic analysis may improve diagnostic confidence and etiologic understanding of rare vascular diseases in veterinary cardiology.

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