A collar for mounting around the neck of an animal, such as a dog, the collar including i) a first part with an inside for receiving the head of the animal, the first part having a flared shape, such as the shape of a truncated cone, and including a peripheral flexible wall defining the flared shape, the wall extending between a first opening leading into the inside and an opposite second opening leading into the inside, and ii) a second part joined to the first part at the second opening, the second part defining a sleeve for extending around the neck, wherein the peripheral flexible wall including a recess extending towards the first opening and defining an enlargement of the second opening.