A disability or decrease in an animal's ability to bear weight on a limb or a decrease in the normal mobility and function of a limb can be considered lameness. It is a clinical sign of a more severe disorder that results in a disturbance in the gait and the ability to move the body about, typically in response to pain, injury, or abnormal anatomy.
Canine lameness, or limping, can be caused by any underlying reason for a dog to have pain. Lameness can be extremely subtle or profound, affecting one limb or several limbs. It can be intermittent or constant, worse in the morning, worse at night, worse after rest, worse after or during exercise.
Lameness can occur in any dog without age, sex or breed predilection. Dogs show different signs pertaining to lameness in different limbs. For example, if only forelamb is involved, the head and neck move upward when the affected limb is placed on the ground and drops when the unaffected limb bears weight. In case of only one hind leg involved, pelvis drops when affected leg bears weight, rises when weight is lifted. And if both hind limbs are involved, forelimbs are carried lower to shift weight forward. In addition, lameness may become worse after strenuous activity or alleviate with rest.
Other signs and symptoms associated with lameness include:
Decreased range of motion
Loss of muscle mass (muscle atrophy)
Abnormal posture when standing, getting up, lying down, or sitting
Abnormal gait when walking, trotting, climbing stairs, or doing figure-eights
Nervous system signs — confusion, trembling, etc.
Bones and/or joints may be abnormal in size, shape
Grating sound with joint movement