In the etiologic classification of cataracts, which category is the most common cause in dogs?

• A. Nutritional
• B. Toxin
• C. Inflammatory/infectious
• D. Hereditary

Answer: (D)

In dogs, cataracts are most often caused by inherited genetic changes. Many canine cataracts are congenital or appear early in life and show breed tendencies, reflecting mutations in genes that code for lens proteins or the developmental pathways that keep the lens clear. Because of these strong familial patterns, hereditary cataracts make up the largest share of cases when you classify cataracts by cause in dogs.

Nutritional cataracts are relatively uncommon in modern dogs with balanced diets. Toxin- or inflammatory/infectious cataracts can occur, but they typically arise secondary to other issues such as exposure to a harmful substance or uveitis, rather than as a primary, widespread cause in the canine population.