Oestrogen belongs to a group of steroid hormones that are mainly synthesised and secreted by the ovaries of mammals. It regulates the differentiation of the reproductive organs and the development and maintenance of the reproductive system. In addition, oestrogen exerts a variety of physiological functions in non-reproductive tissues and organs, including the cardiovascular system, the nervous system, the immune system and the musculoskeletal system. As the most important sex hormone in bitches, oestrogen plays a versatile role in maintaining the health of the musculoskeletal system. It acts via oestrogen receptors (ERa and ERb), which are expressed in bones, muscles, ligaments and tendons. It is known to have a protective effect on intervertebral discs by reducing apoptosis of disc cells, lowering oxidative stress and promoting the expression of antioxidant enzymes. Similar results have been found in women, where the decline in oestrogen levels during menopause accelerates intervertebral disc degeneration and protrusion (IVDD) and increases the risk of back pain, cranial cruciate ligament (CCL) tears, osteoporosis and sarcopenia. In dogs, premature oestrogen loss due to castration also predisposes to these conditions, emphasising the importance of an individual approach when deciding to castrate, particularly in breeds predisposed to IVDD or CCL rupture. To summarise, oestrogen plays a complex but primarily protective role in the musculoskeletal system of bitches: It preserves the disc structure, regulates muscle metabolism and stimulates collagen synthesis in the ligaments. Oestrogen deficiency increases the risk of disc protrusions, CCL ruptures and muscle weakness. These findings emphasise the importance of individual castration decisions and further research into possible hormonal interventions, similar to hormone replacement therapy in women.

Spinal arachnoid diverticulum is a fluid-filled dilation within the subarachnoid space that can result in compressive myelopathy, prompting investigation into optimal surgical management and outcomes. This retrospective study reviewed clinical records of dogs treated surgically between January 2021 and July 2025, including 11 cases that met the criteria of chronic progressive para- or tetraparesis, MRI-confirmed diagnosis, and use of a standardized surgical technique. All dogs underwent dorsal laminectomy followed by durotomy, durectomy, and microsurgical dissection of adhesions performed by the same surgeon, with optical magnification and specialized instruments to ensure consistency. The condition was more common in males, with French Bulldogs overrepresented (n = 6); lesions were thoracolumbar in small breeds and cervical in the single large-breed dog. Short-term outcomes, assessed one month postoperatively, showed neurological improvement in all but one dog. These findings suggest that the described microsurgical approach is feasible and associated with favorable short-term neurological recovery in most cases. However, the absence of long-term follow-up limits definitive conclusions, and further studies are needed to evaluate sustained outcomes.