This study aims to evaluate the effect of the transversus abdominis plane (TAP) block on the blood cells and the inflammatory markers neutrophil- to- lymphocyte ratio (NLR), platelet- to- lymphocyte ratio (PLR), and systemic immune- inflammation index (SII) after the laparoscopic ovariectomy (LapOV) in dogs. 72 healthy bitches undergoing LapOV were randomly allocated to the no- TAP group of dogs under inhaled anesthesia (IA), the TAP- S group (IA and TAP with saline), and the TAP- B group (IA and TAP with bupivacaine). The NLR, PLR, and SII were calculated 1 h before ovariectomy (T0) and at 2-3 h (T1), 6-8 h (T2), and 20-24 h (T3) post- surgery. The number of dogs requiring postoperative analgesic rescue with buprenorphine and the doses administered in each group were recorded. Significant changes were observed in all groups’ postoperative NLR, PLR, and SII over time. Between groups, no differences were observed in any of the ratios at any control point (NLR at T0-T3: p = 0.17, 0.36, 0.80, and 0.95; PLR at T0-T3: p = 0.70, 0.62, 0.21, 0.87; SII at T0-T3: p = 0.29, 0.65, 0.09, and 0.34). A significantly lower number of dogs required analgesic rescue in the TAP-B group (p = 0.0001) and a lower number of doses were administered (p = 0.001). There is no difference in the inflammatory response measured through the complete blood- derived inflammatory markers after the LapOV in dogs when the postoperative pain is managed entirely with opioids or with the TAP block with bupivacaine. The hydrodissection associated with the TAP block technique does not increase the inflammatory response.© 2023. The Author(s).