The skin contraction phenomenon occurs due to the energy emitted by the surgical CO2 LASER affecting the collagen architecture and intracellular water content in tissues. The study aimed to assess how gender, age, breed, body-weight, CO2 LASER emission mode, and potency influence skin contraction following the incision. The study involved 80 dogs (N = 80) of both genders, multiple breeds, undergoing major surgery with CO2 LASER. Subjects were grouped based on LASER potency (12 or 15 Watts) and emission mode (Superpulse—SP or Continuous—CT): GSP12, GSP15, GCT12, and GCT15. A 10 mm incision was performed using the surgical CO2 LASER beam, consistently employing a focal point of 0.4 mm, positioned at a distance of 1 mm from the skin surface, and always maintained perpendicular to it, and resulting lengths measured with a digital caliper. Results were considered significant for p-value < 0.05. GSP12 showed minimal contraction, while GCT15 exhibited the most significant. Male subjects in GCT12, GCT15, and GSP12 experienced less contraction than females. Purebred dogs had greater contraction than mixed breeds. GSP12 individuals showed age-related contraction decrease (p < 0.01), with skin contracting by 0.09 mm per year. Weight and skin contraction trended towards significance (p = 0.06), with a 0.02 mm increase per unit weight. For a constant power of 12 W, the analysis of the relationship between the emission mode of the LASER beam and the final skin contraction (GSP12 vs. GCT12) revealed statistically significant differences (p < 0.01). This study suggests that the use of the Continuous mode of LASER emission, regardless of the power used, is associated with a higher level of final skin contraction.

Project approval registration number by the Research and Teaching Ethics Committee (CEIE),Faculty of Veterinary Medicine—University of Lisbon (FMV_ULisboa), Lisboa—Portugal, N/Refª 015/2022.