The purpose of this study was to perform a histological and biochemical evaluation of the influence of plasma rich in growth factors (PRGF) on muscle regeneration process after a surgically induced grade II muscle laceration. A randomized, single blind, controlled experimental research was conducted including twenty-one adult healthy sheep, randomly divided in three groups (n = 7). A grade II surgical section was performed in the biceps femoris muscle of both hindlimbs. After two days (basal time), intralesional infiltration of autologous PRGF or Saline solution was randomly administered in both hindlimbs. Treatment was repeated once a week. Animal groups were euthanized at 1 (T1), 2 (T2) or 4 (T4) weeks. Histological assessment showed that PRGF intralesional injection induced a significant decrease of inflammatory cells density, significant higher centrally nucleated fibers percentage and significantly smaller fibrotic areas compared to Saline-treated muscles at T1, T2 and T4. Also, lower vascular density, with lower capillaries cross-sectional area, in PRGF group compared to Saline was observed. Biochemical analysis revealed a significant higher expression level ofMYOD1,MYF5andMYOGgenes in PRGF groups at T1 compared to Saline treated muscles. At ultrastructural level, PRGF groups presented scarce edema and loss of connective tissue structure, as well as higher mitochondrial density adequately associated to the sarcomere unit in contrast to the Saline group. In conclusion, histological, biochemical, and ultrastructural results showed that PRGF treatment improved muscle regeneration process leading to more mature histological aspect in newly formed muscle tissue after a surgically induced grade II muscle injury.

This study performs an analysis that will enable the evaluation of the quality, durability, and structure of repaired cartilaginous extracellular matrix tissue using an autologous-based particulated autograft cartilage and platelet-rich plasma treatment (PACI + PRP). A single-blind controlled experiment was conducted on 28 sheep to evaluate the efficacy of the PACI + PRP treatment for cartilage defects. Full-thickness 8 mm diameter defects were created in the weight-bearing area of both knees. The right knees received PACI + PRP. The left knees were treated with Ringer’s lactate solution (RLS) or hyaluronic acid (HA) injections. Sheep were euthanized at 9- or 18-months post-surgery. An extensive immunohistochemical analysis was performed to assess collagen types (I, II, III, V, VI, IX, X, XI) and aggrecan positivity. A semiquantitative scoring system provided a detailed evaluation of immunostaining. Collagens and aggrecan scores in the PACI + PRP groups were similar to healthy cartilage. Significant differences were found in collagens associated with matrix maturity (II and V), degradation (IX), structure and mechanics (VI), and hypertrophy (X) between healthy cartilage and RLS- or HA-repaired cartilage. The PACI + PRP treatment advanced the repair cartilage process in chondral defects with mature hyaline cartilage and enhanced the structural and mechanical qualities with better consistent cartilage, less susceptible to degradation and without hypertrophic formation over time.

Background: This study measured serum biomarkers at baseline and during an ovariohysterectomy in healthy female Spanish greyhounds, aiming to enhance the objectivity of current methods for assessing acute postoperative pain in dogs. Methods: Blood samples from 20 Spanish greyhounds were collected before drug administration (T0‐baseline). Premedication included dexmedetomidine and methadone, followed by propofol and isoflurane. Four additional samples were taken: post‐second ovariectomy (T1‐PostOvary), 4 hours post‐premedication (T2‐PreRescue), 30 minutes post‐rescue methadone (T3‐PostRescue) and 24 hours post‐extubation (T4‐24H). Biomarkers were quantified via ELISA, and postoperative pain was assessed using the short‐form Glasgow scale (Glasgow‐SF). Data analysis included ANOVA, Friedman test and Spearman's correlation. Results: Glutamate ( p = 0.007; Kendall's W = 0.186) and calcitonin gene‐related peptide (CGRP) ( p = 0.001; = 0.324) peaked at T0‐baseline. Cortisol peaked at T3‐PostRescue ( p = 0.041; = 0.099). Glasgow‐SF scores increased postoperatively compared with T0‐baseline ( p = 0.001; Kendall's W = 0.612), without significant biomarker correlation. Limitations: Sample homogeneity may limit result generalisability and lack of acclimatisation may introduce bias, as initial stress could affect the synthesis of stress‐related biomarkers. Conclusions: Although glutamate, CGRP and cortisol levels fluctuated over time—with glutamate and CGRP peaking at T0‐baseline—none proved useful for assessing postoperative pain compared with conventional clinical parameters.