Abstract Objective The aim of this study was to assess the protective effect of transecting a partially ruptured cranial cruciate ligament (CCL) during tibial plateau levelling osteotomy (TPLO) surgery on postoperative patellar ligament thickness (PLT) and shortening. Study Design Dogs with partial CCL rupture that underwent a unilateral TPLO were included. The population was divided into two groups: remnant CCL transected (study group) and left in situ (control group). Preoperative and 6-week postoperative measurements of PLT, in three specific locations, and patellar ligament length (PLL) were collected. Risk factors for PLT and shortening were also included. Results Fifty-two dogs (56 stifles) with partial CCL rupture were retrospectively included. Twenty-nine stifles (51.8%) had the remnant CCL transected (study group) and 27 stifles (48.2%) had the remnant CCL left in situ (control group). Significant differences were found on PLT measurements between pre- and 6-week post-surgery for all three ligament locations with greatest difference at the middle region. Median PLL was significantly shorter 6-week post-surgery for both groups. No significant differences in PLT nor PLL were identified between procedures where the remnant was transected or not. Conclusion This study did not identify a protective effect of transecting the CCL remnant on PLT or patellar ligament shortening, contrary to other reports within the literature. Further investigation is needed in the form of prospective studies with higher number of cases to understand the clinical implications of patellar ligament thickening and shortening in dogs.