Hereditary cataracts, a condition common in over 60 breeds, are a major source of blindness and vision impairment in dogs. In Northern dog breeds, such as Siberian Huskies, Alaskan Malamutes, and Samoyeds, cataracts are particularly common—and have been increasing in prevalence over the last forty years.
This rise in impacted dogs prompted our scientists to dig into the data and hunt for genetic links that could further our understanding of this inherited condition. Read on to learn what the team discovered.
A closer look at cataracts in northern breeds
Northern breeds tend to have bilateral cataracts in the posterior polar subcapsular area of the lens (PPSC). In Siberian Huskies, these cataracts often develop early in life, around 9 months to 2 years of age, suggesting a strong genetic component. To understand the genetic link, scientists from Wisdom Panel and the University of Cambridge embarked on the largest genetic study to date focused on cataracts in cold-climate breeds.
To begin, they analyzed genome-wide single nucleotide polymorphism (SNP) data from Siberian Huskies, Alaskan Malamutes, and Samoyeds—some with cataracts, some without—looking for genetic differences. Then, they performed targeting resequencing to search for variants that may contribute to the condition. Through this analysis they zeroed in on common variants in the carnitine palmitoyltransferase 1A (CPT1A) gene.
CPT1A: a gene of interest
Our researchers found a strong association between PPSC cataracts and markers in the CPT1A gene in four Northern breeds of domestic dog—the Siberian Husky, Samoyed, Icelandic Sheepdog and Norwegian Buhund—but not the Alaskan Malamute. This gene plays an important role in how the body uses fat for energy, and it’s active in several tissues—including the lens and retina of the eye.
In Siberian Huskies, the CPT1A variant was found significantly more often in dogs with cataracts compared to those without. This finding was supported by additional data from Samoyeds, Icelandic Sheepdogs, and Norwegian Buhunds.
While not all dogs with the variant had cataracts—and not all dogs with cataracts had the variant—the association suggests that CPT1A may be part of the genetic risk profile for this condition.
For the full analysis, check out the published study in PLOS One.
What this means for dog parents
This discovery adds an important piece of information to our understanding of inherited eye disease in dogs. Once thought to be a simple Mendelian condition, hereditary cataracts, at least in Northern breeds, appear to be a more complex disease involving more than one gene and environmental factors.
Based on these insights, here are some practical takeaways for pet parents:
- Consider your breed’s risks. Northern breeds appear to have a higher risk for hereditary cataracts, and this study helps explain why.
- Get regular eye exams. Especially for at-risk breeds, early veterinary eye exams can help detect issues sooner.
- Understand the implications. PPSC cataracts often don’t require treatment, unless they are very large, but may result in mildly impaired vision.
Why this discovery matters
This study identifies a potential genetic contributor to inherited cataracts in multiple breeds. It opens the door for future research that down the road may lead to the development of DNA screenings that can help identify dogs at higher risk.
While the CPT1A variant is just a piece of the puzzle, it offers a better understanding of hereditary cataracts in dogs and brings us one step closer to preventing this condition in future generations of dogs.
