Some breeds—and particularly Standardbreds—may be more likely to develop cataracts. Those are the findings of a study published by researchers from Cornell University and the University of California, Davis.

Cataracts are the clouding of the normally clear lens in the center of the eye. They impair vision and can lead to total blindness. Congenital cataracts are present at birth, and juvenile cataracts develop early in a horse’s life. Most cataracts in horses develop later in life, however, often following trauma or inflammatory disease.

The Standardbred is an American breed best known as harness racers. They can compete at the trot or the pace.

To determine whether horses might inherit susceptibility to cataracts, researchers from Cornell University and the University of California, Davis (UCD) reviewed the records of 101 horses admitted to referral clinics at either institution for congenital and juvenile forms of the condition.

Standardbreds comprised 32.5 percent of congenital/juvenile cataract cases at Cornell, but only 10 percent of the total equine hospital population there. At UCD, 4.3 percent of cataract cases were in Standardbreds. There, the breed comprised only 1.3 percent of the equine hospital population.

The researchers conclude, “the over-representation of the Standardbred breed for congenital and juvenile cataracts…suggests an underlying genetic basis in the breed.” Therefore they call for further study.

Reference: “Breed predispositions to congenital and juvenile cataracts in horses at two academic institutions,” Equine Veterinary Journal, December 2023

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