The use of antibiotics in farm animals is one of the main reasons for the development of resistant bacterial strains (e.g., zoonotic pathogens). Therefore, save alternatives are needed. Here, we examined how post-hatch application (day one to seven of life) of the probiotic Enterococcus faecium AL41 (EF) affects the development and tissue properties of the broiler pectoralis major muscle (PM). Expression of regulators, namely IGF-1, PAX7, and MYF5, was also investigated. At day 1 (n = 6), and days 5, 8, and 12 (n = 10), muscle samples were taken from control and EF supplemented chicks. From day 5 on, myonuclei number per fiber was elevated in EF chicks. Improved capillarization (from day 8), larger myofibers, increased body and PM weights (day 12) were found in the EF group. Part of our findings is explainable by higher intramuscular expression of IGF-1 and lower MYf5 expression in EF birds. In both groups IGF-1 expression decreases with age, thereby increasing the cellular myogenic potential. However, a strong increase in PAX7 expression and more PAX7-positive nuclei were found in EF chicks at day 12. We conclude that EF supplementation improves PM growth and health due to positive effects on bioavailability and fusion capacity of SATC progeny and better tissue perfusion.

This case report describes nodular dermatofibrosis in an 11-year-old female dog of the German Shepherd breed. Previously, at the age of 6 years (initial stage), a sample from a tumorous nodule on her back was removed. Histological examination of the sample from this period showed hyperplasia of cells with a lobular structure. Immunohistochemistry staining demonstrated focal positivity to pancytokeratin. In the terminal stage (at 11 years of age), clinical examination revealed apathy, uncoordinated movement of the hind limbs, obstipation, anorexia and occasional vomiting with progressive weight loss. Skin inspection found multiple skin ulcerating tumorous lesions localized in the sacral region of the back and intercostally, partly fluctuating around the size 4 cm in diameter. Necropsy revealed an intraabdominal tumour localized among intestinal loops. Nodular lesions were found also in the lung parenchyma, on the dorsal surface of the epiglottis, in the myocardium, the cortex and the medulla of the kidneys, the adrenal gland, and in the intestinal wall. Histological analysis showed systemic production of fibrous nodules and formation of fibrous tissue with atrophy of parenchyma tissue. However, no connection between dermatofibrosis and adenocarcinoma of the kidney was found in this case, which was supplemented with pancytokeratin antibody. CD3 + lymphocytes were observed mainly in the zone of cell proliferation and in the interface towards the fibrous layer. Macrophages were seen mainly in the transitional zone between cellular and fibrous part. This indicated participation of monitored immunocompetent cells in fibroblast degradation.