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Disorder of the Gait in Dogs

Lameness 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.

Symptoms and Types

Lameness may involve one or more limbs and varies in severity from subtle pain or tenderness to an inbability to place any weight on the limb (i.e., carrying the leg). If only one forelimb 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. Meanwhile, if only one hind limb is involved, the 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:

• Pain
• 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

Causes

Forelimb lameness in still growing dogs that are less than 12 months of age

• Osteochondrosis of the shoulder — from a group of orthopedic diseases that occur in rapidly growing animals
• Shoulder dislocation or partial dislocation of congenital origin
• Osteochondrosis of the elbow
• Ununited anconeal process - a form of elbow dysplasia, an abnormality in the maturation of cells within a tissue
• Fragmented medial coronoid process - degeneration in the elbow
• Elbow incongruity - failure of the bones to grow at the same rate
• Avulsion (tear) or calcification of the flexor muscles of the elbow
• Asymmetric (uneven) growth of the radius and ulna (bones of the foreleg)
• Panosteitis — inflammation of the bones
• Hypertrophic osteodystrophy — a disease characterized by decreased blood flow to the part of the bone adjacent to the joint
• Trauma to the soft tissue, bone, or joint
• Infection – may be local or generalized (systemic)
• Nutritional imbalances
• Congenital abnormalities (present at birth)

Forelimb lameness in mature dogs that are older than 12 months of age

• Degenerative joint disease - progressive and permanent deterioration of joint cartilage
• Bicipital tenosynovitis - inflammation of the tendons of the biceps
• Calcification or mineralization of the supraspinatus or infraspinatus tendon – the rotator cuff muscles
• Contracture of the supraspinatus or infraspinatus muscle – shortening of the muscle's connective tissue due to scarring, paralysis, or spasms
• Soft-tissue or bone cancer – may be primary, or metastatic (cancer that has spread)
• Trauma to the soft tissue, bone, or joint
• Panosteitis – inflammation of the bones
• Polyarthropathies – arthritic and inflammatory diseases of the musculoskeletal system
• Polymyositis - inflammation of the muscle fibers
• Polyneuritis – widespread inflammation of the nerves

Hindlimb lameness in growing dogs that are less than 12 months of age

• Hip dysplasia - overgrowth of cells
• Avascular necrosis of the femoral head - Legg-Calvé-Perthes disease, where the ball of the thighbone in the hip doesn't get enough blood, causing the bone to die
• Osteochondritis of stifle - fragments of cartilage or bone have become loose within the knee joint
• Patella luxation - medial or lateral disorder, in which the kneecap dislocates or moves out of its normal location
• Osteochondritis of the hock - fragments of cartilage or bone have become loose within the hock, the joint of the hind leg
• Panosteitis – inflammation of the bones
• Hypertrophic osteodystrophy - a disease characterized by decreased blood flow to the part of the bone adjacent to the joint
• Trauma to the soft tissue, bone, or joint
• Infection – may be local, or generalized (systemic)
• Nutritional imbalances
• Congenital abnormalities (present at birth)

Hindlimb lameness in mature dogs that are greater than 12 months of age

• Degenerative joint disease - progressive and permanent deterioration of joint cartilage), secondary to hip dysplasia (abnormal formation of the hip joint)
• Cruciate ligament disease - the tearing of an important ligament in the knee joint
• Avulsion (tearing) of the long digital extensor tendon (the toe extender tendon)
• Soft-tissue or bone cancer – may be primary, or metastatic (cancer that has spread)
• Trauma to the soft tissue, bone, or joint
• Panosteitis – inflammation of the bones
• Polyarthropathies – arthritic and inflammatory diseases of the musculoskeletal system
• Polymyositis - inflammation of the muscle fibers
• Polyneuritis – widespread inflammation of the nerves

Risk Factors

• Breed (size)
• Overweight
• Frequent, strenuous activity

Diagnosis

Your veterinarian will perform a thorough physical exam on your pet, taking into account the background history of symptoms and possible incidents that might have led to this condition. Standard tests include a complete blood profile, a chemical blood profile, a complete blood count, and a urinalysis.

Because there are so many possible causes for lameness, your veterinarian will most likely use differential diagnosis. This process is guided by deeper inspection of the apparent outward symptoms, ruling out each of the more common causes until the correct disorder is settled upon and can be treated appropriately.

Your veterinarian will first try to differentiate between musculoskeletal, neurogenic and metabolic causes. The urinalysis may determine whether a muscle injury is reflected in the readings. Diagnostic imaging will include X-rays of the area of the lameness. Computed tomography (CT) scans and magnetic resonance imaging (MRI) will also be used when appropriate. Your doctor will also take samples of joint fluid for laboratory analysis, along with tissue and muscle samples in order to conduct a muscle and/or nerve biopsy to look for neuromuscular disease.