OBJECTIVE To radiographically compare patellar ligament length (PLL) in dogs undergoing tibial plateau leveling osteotomy (TPLO) for unilateral cranial cruciate ligament rupture at preoperative, postoperative, and follow-up evaluations. ANIMALS 105 dogs that underwent TPLO for unilateral cranial cruciate ligament rupture at a referral veterinary hospital from October 1, 2008, through November 30, 2017. PROCEDURES Medical records were reviewed to obtain information on dog signalment, surgical procedure, and radiographically measured PLL at preoperative, postoperative, and follow-up evaluations. RESULTS Dogs undergoing TPLO had a shorter PLL at the postoperative and follow-up evaluations, compared with the PLL at the preoperative evaluation. Mean ± SD overall unadjusted PLL decreased significantly by 2.3 ± 3.4% between the preoperative and postoperative evaluation and by 2.8 ± 3.9% between the preoperative and follow-up evaluation. The PLL did not differ significantly between the postoperative and follow-up evaluation; mean PLL decreased by 0.4 ± 3.8% between the postoperative and follow-up evaluation. CONCLUSIONS AND CLINICAL RELEVANCE The PLL was shorter after TPLO in dogs, which was similar to changes observed for humans after high tibial osteotomy procedures. Further evaluation of clinical assessments, joint mobility, ultrasonographic assessments, and kinematic results are needed to determine the relevance of the PLL and whether a decrease in ligament length results in decreased mobility and persistent lameness in dogs, as has been reported for humans.