*4.4. Polymers Implantation*

An overview of the implantation sites is depicted in Figure 9. The lateral surface (LS) of the neck was used as the implant site. The animal evaluated here was used in the pilot study that preceded our previous research [22]. The animal received the PLA implant in different locations between the right and left LS, aiming to investigate whether there would be interference from the inflammatory process between the implants, and whether the difference in thickness of the subcutaneous tissue observed via ultrasound would interfere with the inflammatory process.

**Figure 9.** Schematic illustration showing the evaluation sites of a horse implanted with PLA.

Before implanting the biomaterial, six areas of approximately 8 cm2 on the LS (three on the left and three on the right) were shaved, and antisepsis was performed with 2% chlorhexidine digluconate and 70% ethyl alcohol. Subsequently, the animal was sedated with intravenous administration of xylazine hydrochloride (1 mg.kg−1). Afterward, local anesthetic infiltration was performed around each incision site with 2.0 mL of 2% lidocaine hydrochloride. A 2 cm horizontal incision was made using a #15 scalpel blade in the determined area on the LS. A space between the skin and cutaneous muscle was obtained by blunt divulsion and the polymer implanted. It is important to highlight that the divulsion was performed ventrally to the incision so that the skin suture did not interfere in the evaluations. Then, skin suture was performed in a simple interrupted pattern with nylon 0. Postoperative procedures consisted of cleaning the area using gauze and 0.9% saline solution and fly repellent ointment around the surgical wound once a day for 10 days. No analgesic and/or anti-inflammatory medication was provided during the experimental period. The stitches were removed on the 7th postoperative day. The same surgeon performed all surgical procedures.

## *4.5. Evaluation Methods*
