A device for measuring the angle of inclination between an incisor occlusal plane, defined by the contact surface between an animal's upper and lower dental arches, and two alternative reference planes, one passing through the center of the animal's incisor plane and the temporomandibular joints, the other passing through the center of the incisor plane and the eyes, wherein said device comprises: - an element of contact with the animal, - at least one first movable member revolvingly attached to said contact element around a first axis of rotation, - and at least one graduated scale located on said contact element, or on said first movable member for measuring their relative rotation, wherein said contact element comprises a locator plate sized to fit inside the animal's mouth, between the upper and lower dental arches, and to be aligned with said occlusal plane, with an abutment on either of the two sides; and wherein the device also comprises a second movable member revolvingly connected to said first movable member around a second axis of rotation, said first and second axes of rotation (L1, L2) being substantially orthogonal to one another so as to enable the alignment of both said first movable member and said second movable member with said reference planes at the center of the incisor plane and wherein said first axis of rotation is substantially aligned with said locator plate and with a longitudinal vertical plane passing through the center of the incisor plane and the midpoint between the animal's eyes, with said locator plate aligned with said occlusal plane, and wherein said second axis of rotation is substantially perpendicular to the first axis and passes through the point where a first intersecting line between the locator plate and the sagittal plane, and a second crosswise intersecting line between the locator plate and the abutment cross over, and consequently parallel to the first movable element and integrally connected thereto, and wherein said first movable member comprises a second graduated scale for measuring the relative rotation between said first and second movable members. - an element of contact with the animal, - at least one first movable member revolvingly attached to said contact element around a first axis of rotation, - and at least one graduated scale located on said contact element, or on said first movable member for measuring their relative rotation, and wherein the device also comprises a second movable member revolvingly connected to said first movable member around a second axis of rotation, said first and second axes of rotation (L1, L2) being substantially orthogonal to one another so as to enable the alignment of both said first movable member and said second movable member with said reference planes at the center of the incisor plane and wherein said first axis of rotation is substantially aligned with said locator plate and with a longitudinal vertical plane passing through the center of the incisor plane and the midpoint between the animal's eyes, with said locator plate aligned with said occlusal plane, and wherein said second axis of rotation is substantially perpendicular to the first axis and passes through the point where a first intersecting line between the locator plate and the sagittal plane, and a second crosswise intersecting line between the locator plate and the abutment cross over, and consequently parallel to the first movable element and integrally connected thereto, and wherein said first movable member comprises a second graduated scale for measuring the relative rotation between said first and second movable members.