To describe clinical features of dogs < 2 years old with rupture of the cranial cruciate ligament (CCL) and to evaluate breed, sex, and body weight as risk factors. Case-control study. 201 dogs < 2 years old with rupture of the CCL and 804 age-matched control dogs. Medical records were reviewed for breed, sex, and body weight, and results were compared with results of age-matched control dogs. Breed predisposition was detected for Neapolitan Mastiff, Akita, Saint Bernard, Rottweiler, Mastiff, Newfoundland, Chesapeake Bay Retriever, Labrador Retriever, and American Staffordshire Terrier. Increased risk was detected for neutered males and neutered females, compared with sexually intact males and sexually intact females, respectively. Differences in prevalence of rupture of the CCL were not detected between all males and females, sexually intact males and sexually intact females, or neutered males and neutered females. Body weights of dogs with ruptured CCL were significantly greater than those of control dogs. Several large breeds of dogs are predisposed to rupture of the CCL at a young age.
