Corneal dystrophy is a disease of the cornea, common in dogs. Although the condition usually doesn't affect vision, your dog's eye may cloud. Corneal dystrophy is genetic, and many breeds are predisposed. These breeds include Boston terriers, Chihuahuas, dachshunds, German shorthaired pointers, and German wirehaired pointers. A veterinarian or a veterinary ophthalmologist will diagnose corneal dystrophy with a comprehensive eye examination and diagnostic tests if necessary. In most cases, treatment is not required, and the prognosis is good.
What Is Corneal Dystrophy?
Corneal dystrophy is a disease that affects the cornea, the eye's frontmost transparent layer. Corneal dystrophy causes a buildup of material in the cornea, causing opacity and potentially obscuring vision. The opacity can usually be attributed to the accumulation of lipids or calcium deposits. Some may confuse corneal dystrophy with cataracts, but these diseases affect different parts of the eye. Cataracts affect the eye's lens, while corneal dystrophy affects the cornea. Corneal dystrophy is a progressive disease, meaning it worsens over time.
There are three different types of corneal dystrophies, classified by which of the five corneal layers the disease affects. These are epithelial corneal dystrophy, stromal corneal dystrophy, and endothelial corneal dystrophy.
Symptoms of Corneal Dystrophy in Dogs
Many dogs with corneal dystrophy don't exhibit painful symptoms, but symptoms and severity vary with the type of dystrophy and the stage of the disease. If you notice an abnormality in your dog's eye, visit your vet.
Your dog's symptoms will vary based on its type of corneal dystrophy, but in most cases, you will notice clouding in the eye. For many dogs, eye clouding is the only symptom of the disease and vision isn't impaired. Still, clouding can sometimes be accompanied by vision loss and light sensitivity. In advanced cases, especially with endothelial corneal dystrophy, your dog may experience painful fluid buildup and ulcers in its eyes and paw at its face as a result.
Causes of Corneal Dystrophy
Corneal dystrophy is genetic and disproportionately affects an extensive group of breeds.
- Genetics: Corneal dystrophy is an inherited disease. Many breeds are predisposed to corneal dystrophies, including but not limited to Boston terriers, Chihuahuas, dachshunds, German shorthaired pointers, and German wirehaired pointers. Older dogs and female dogs are thought to be more likely than others to develop most of corneal dystrophy, however dogs of both sexes and all ages can develop the disease.
- High calcium and cholesterol: Veterinarians have noted that high cholesterol and calcium levels may contribute to or exacerbate corneal dystrophy.
Diagnosing Corneal Dystrophy in Dogs
After your veterinarian performs a preliminary eye examination on your dog, they may refer you to a veterinary ophthalmologist for more comprehensive diagnostics. The ophthalmologist will examine your dog's eye with a microscope and bright light that will allow them to see the abnormal buildup in the cornea. Your vet may perform eye pressure and tear production tests and check for corneal ulcers. These tests are often accompanied by blood analysis to rule out other ocular diseases.
Treatment & Prevention
Once your dog is diagnosed with corneal dystrophy, your veterinarian will prescribe a treatment plan. if necessary. If your dog requires treatment, it will usually begin with an antibiotic and then vary depending on the type and stage of dystrophy. Your vet may recommend changes in diet, and prescription eye drops, and in severe cases, surgery may be recommended.
The disease progresses slowly and doesn't always necessitate treatment. The secondary eye issues that the disease may cause are often more harmful than the dystrophy itself.
Because it is an inherited disease, you can't prevent corneal dystrophy. Regular monitoring of cholesterol and calcium blood levels and general protection from viruses and bacteria may help keep the disease from worsening. Dogs with a history of corneal dystrophy should not be bred.
Prognosis for Dogs With Corneal Dystrophy
Typically, the prognosis for dogs with corneal dystrophy is good but depends on the severity of the disease. Most dogs with corneal dystrophy never experience vision loss and lead normal, healthy lives.
Types of Corneal Dystrophy
- Epithelial corneal dystrophy - Epithelial corneal dystrophy affects the outermost layer of the cornea and usually doesn't cause symptoms.
- Stromal corneal dystrophy - Stromal corneal dystrophy affects the cornea's middle layer. This type of dystrophy can be caused by the accumulation of fat droplets in the cornea, and dogs are most likely to be diagnosed when young. Stromal cornea dystrophy usually doesn't cause pain or symptoms.
- Endothelial corneal dystrophy - Endothelial corneal dystrophy affects the cornea's innermost layer and tends to occur in middle-aged dogs. Although there are usually no symptoms at the onset, in advanced cases, fluid can accumulate on the edge of the cornea and spread over time, leading to ulcers and vision loss.
Will corneal dystrophy make my dog blind?
Most cases of corneal dystrophy will not lead to blindness. Still, if you notice clouding in your dog's eye, visit your vet for a definitive diagnosis and discuss possible treatment.
What's the difference between corneal dystrophy and cataracts?
Although both conditions cause clouding in the eye, cataracts affect the eye's lens and corneal dystrophy affects the cornea.
Is my dog's breed predisposed to corneal dystrophy?
There are dozens of breeds predisposed to corneal dystrophy. Talk to your vet to find out if your dog is at a heightened risk.
Shull, OR et al. Phenotypic Characterization of Corneal Endothelial Dystrophy in German Shorthaired and Wirehaired Pointers Using In Vivo Advanced Corneal Imaging and Histopathology. Cornea, 2018;37(1):88-94. Ophthalmology and Vision Science, School of Veterinary Medicine. doi:10.1097/ICO.0000000000001431
Leonard, BC et al. A Retrospective Study of Corneal Endothelial Dystrophy in Dogs (1991-2014). Cornea. 2021;40(5):578-583. National Library of Medicine. doi:10.1097/ICO.0000000000002488
Thomasy, SM et al. In Vivo Imaging of Corneal Endothelial Dystrophy in Boston Terriers: A Spontaneous, Canine Model for Fuchs' Endothelial Corneal Dystrophy. Invest Ophthalmol Vis Sci. 2016;57(9):OCT495-OCT503. Ophthalmology and Vision Science, School of Veterinary Medicine. doi:10.1167/iovs.15-18885