The brain is one of the most vital organs in the body, and in dogs, it relies on an invisible yet powerful line of defense: the blood-brain barrier (BBB). This microscopic shield keeps harmful substances out while allowing essential nutrients to flow in, preserving the delicate balance of the central nervous system. But what happens when this protective barrier is compromised? A recent review by Dimitri Bassalo, Stephen G. Matthews, and Enrrico Bloise explores the crucial role of the BBB in canine health and disease, revealing its strengths, weaknesses, and the profound impact it has on neurological conditions in dogs.