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| HIP & LEG PROBLEMS
A proper physical examination of your Bulldog is essential to determine the source of the problem. Because most joint and leg problems of growing dogs have some degree of lameness, a thorough lameness and gait examination are essential. For purposes of this discussion, lameness is defined as an alteration in the normal gait of the animal. When evaluating a lame dog, the veterinarian should examine the entire animal because the source of the lameness may not be orthopedic, but may involve other systems such as the neurologic system. The lameness should be localized to a specific area by gait analysis and palpation. At this point, further diagnostics, such as radiographs or joint taps, may be required to make the diagnosis. Occasionally, advanced diagnostics, such as computerized tomography, magnetic resonance imaging (MRI), nuclear scans, or advanced gait analysis may be required for diagnosis.
GENERAL CAUSES OF JOINT AND LEG PROBLEMS IN GROWING DOGS
The possible causes of lameness in young dogs may be divided into categories: congenital, developmental, traumatic, idiopathic, infectious, nutritional/metabolic, and neoplastic (Table 1). Congenital abnormalities are changes that are present at birth and therefore are usually seen in very young dogs. Developmental abnormalities occur during the growing stages of the dog’s life and often have a genetic basis. Traumatic injuries are common in young dogs due to their adventurous nature and playfulness. Idiopathic abnormalities have unknown causes or origins. Orthopedic conditions are frequently associated with nutritional imbalances, deficiencies, or excesses. Some metabolic conditions may be related to nutritional issues, or may involve other body systems. Infectious and neoplastic causes of lameness in growing dogs are uncommon.
CONGENITAL CAUSES OF JOINT AND LEG PROBLEMS IN GROWING DOGS
Forelimb
Congenital dislocation (luxation) of the shoulder is an uncommon cause of lameness in young dogs, but is usually seen in small breeds such as Toy Poodles, Chihuahuas, and Pomeranians.1 The dislocation is a result of inherited weakness to the supporting structures of the shoulder joint. The luxation is usually bilateral and the dog may only have mild lameness. Surgery may be performed, but some animals can learn to compensate quite well.
Congenital dislocation of the elbow is also a hereditary disease affecting mostly small breed dogs such as Pekingnese, Boston Terriers, Miniature Poodles, Pugs, Chihuahuas, Miniature Pinschers, Dachshunds, and Yorkshire Terriers. This disease has also been seen in larger breed dogs such as Bulldogs, Basset Hounds, Akitas, Shelties, and German Shepherd Dogs. The luxation is usually bilateral. Dogs have varying degrees of lameness, from essentially normal to non-weight bearing. This condition is caused by abnormal development of the elbow joint. Most dogs require aggressive, early treatment, such as surgery, to stabilize the joint and prevent other abnormalities, such as arthritis.
Failure of a limb to develop (limb agenesis) is a rare congenital defect in which the bones do not develop properly. The radius is one of the more commonly affected bones and its absence is apparent immediately after birth. Due to the severity and difficulty in treating this disease, amputation may be the treatment of choice.
Hind limb
Patellar (knee cap) dislocation is a common abnormality in toy, miniature, and some large breed dogs (Figure 1). Medial (toward the inner surface) and lateral (toward the outer surface) luxations occur, but medial luxation is most common. Patellar luxation is usually a congenital disorder that is thought to be caused by abnormal hip conformation and a shallow patellar groove. Clinical signs are typically an intermittent lameness and an abnormal hopping or skipping gait. Patellar luxations are graded on a scale of 1 to 4, depending on the severity of the luxation. Surgical treatment is recommended for symptomatic dogs to control pain, improve gait, and prevent secondary degenerative changes leading to arthritis. Interestingly, a significant percentage of patients with patellar luxation develop rupture of the cranial cruciate ligament. The combination of these conditions is much more serious than either one alone.
DEVELOPMENTAL CAUSES OF JOINT AND LEG PROBLEMS IN GROWING DOGS
Forelimb
Osteochondrosis (OC) is defined as a disturbance of the change of cartilage to bone. The cause of this disease is not completely understood, however, it is known to be a multifactorial disease process which includes genetic, nutritional, traumatic and vascular components. The abnormal area of cartilage is structurally and mechanically inferior to the surrounding cartilage and bone. The diseased cartilage will often detach as a flap. The condition is then called osteochondritis dissecans (OCD), which may cause joint abnormalities, including synovitis (inflammed joint fluid) joint swelling, arthritis, pain, and lameness.
Common sites of OCD in the forelimb are the head of the top part of the arm bone and the elbow joint between the arm and the forearm bone (medial humeral condyle).2,3 Radiographs are usually diagnostic for OCD (Figure 2). This disease is usually managed surgically and consists of removal of the flap and surgical removal of surrounding abnormal tissue. Surgical intervention typically has favorable results in the shoulder with about 90% of animals returning to acceptable function. Success rates for elbow OCD are less predictable.
Elbow dysplasia is an encompassing term used to describe a group of developmental abnormalities affecting the elbow joint of growing dogs. Included in this term are fragmented medial coronoid process (FCP), ununited anconeal proess (UAP), and OCD of the inside aspect of the elbow joint surface (Figures 3–5).4,5 Some also consider uneven (asynchronous) growth of the radius and ulna with elbow incongruity a form of elbow dysplasia. Elbow dysplasia is most commonly seen in large and giant breed dogs, especially in Bernese Mountain Dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers. Males are more commonly affected. Dogs with elbow dysplasia typically present around 5–8 months of age and it is commonly seen in both elbows. Diagnosis is based on clinical signs, signalment and radiographs. Computerized tomography is helpful in early cases of FCP. Depending on the specific condition, either medical or surgical treatments may be recommended. Medical therapy includes controlling lean body weight, controlled exercise, monitoring pain, and non-steroidal anti-inflammatory medications. Surgical therapy is aimed at removing any abnormal cartilage or bone and attempting to return the joint to more normal function. Arthroscopic removal may have advantages over an open arthrotomy, particularly regarding removal of FCP.
Hind Limb
Hip dysplasia (HD) is a common developmental defect with genetic and nutritional causes.6-9 HD is more common in large breed dogs, and nearly always involves both sides, although one side may be more severely affected. HD starts with slackness in the joint and partial disclocation of the hip joints (Figure 6). This creates abnormal forces on the joint leading to degeneration and arthritis over time. Clinical signs include gait changes and pain. A definitive diagnosis is made by radiographs. Early evaluation using PennHip* may give some indication whether or not a dog may develop hip dysplasia.8,10 Medical treatment includes weight loss or control, physical rehabilitation and controlled exercise, nonsteroidal anti-inflammatory medications, and disease-modifying osteoarthritis agents, such as glucosamine and chondroitin sulfate. Surgical techniques in immature dogs include fusing the pubic bone of the pelvis, triple pelvic osteotomy (Figure 7), and removal of the head of the thigh bone (femoral head and neck ostectomy [FHO]).9,11 Surgical procedures in older dogs with secondary osteoarthritis are limited to salvage procedures, including total hip replacement and FHO.9
Legg-Calve-Perthe disease is seen in small and miniature dogs. The exact cause is unknown; however, genetic and traumatic causes have been implicated. The disease progresses to necrosis or degeneration of the femoral head. The animal is usually lame, often after minor trauma. Radiographs are diagnostic, showing the abnormal femoral head. Treatment is usually performed by removing the femoral head, a procedure called femoral head and neck ostectomy. Prognosis for function after surgery is very good.
OCD is also occasionally seen in the hind leg. Common sites include the knee joint and the hock joint.12,13 OCD of the knee is most commonly seen in large breed dogs such as Great Danes, Labrador and Golden Retrievers, Newfoundlands, and German Shepherd Dogs; it may also be seen in Akitas, Chow Chows, Boxers, Bull Terriers, Mastiffs, and Samoyeds. Diagnosis is by clinical signs of chronic hind limb lameness which worsens after exercise, and seeing the lesion on radiographs. Surgical treatment involves removing the abnormal cartilage and the surrounding tissue. Dogs with stifle OCD may be predisposed to rupture of the cranial cruciate ligament in the future. OCD of the hock joint is also seen in the large breeds, but especially so in Rottweilers. One study indicated no difference in long-term outcome between medical treatment and surgical removal of the cartilage flap in hock OCD, but arthroscopic removal may offer some advantages over traditional surgical removal. In general, stifle OCD has a better prognosis than hock OCD.
Traumatic Causes of Joint AND Leg Problems in Growing Dogs
Forelimb
Fractures, dislocated joints, tendon and ligament sprains and strains, and muscle damage occur frequently in young dogs. Numerous fractures of the canine forelimb may occur (Figure 8).14,15 Many dogs with forelimb fractures often have other concurrent trauma, such as chest injuries, that must be addressed. Unique to young dogs are Salter-Harris fractures, which are fractures of the area of the bone that is growing (ie, the growth plate or physis) in skeletally immature dogs. Growth plate fractures usually heal very well, but the growth plate usually closes prematurely, resulting in limb shortening, and in the case of the radius and ulna, uneven growth, limb deformities, and partial dislocation of the elbow and carpal joints.16 Growth plate fractures should be reduced and stabilized as soon as possible for the best outcome.
Fractures of the digits (toes) are fairly common in young dogs that get their foot caught in fences or gates, or have them stepped on. Most heal reasonably well with splinting and rest, but occasionally surgery is necessary. Soft tissue injuries in growing dogs occur, but should only be diagnosed after ruling out other more serious injuries.
Hind limb
Rupture of the cranial cruciate ligament (CrCL) is a major cause of degenerative joint disease in the knee and is one of the most common injuries seen in the dog (Figure 9). Generally, rupture of the CrCL is a degenerative condition in middle-aged to older dogs. Fortunately, this condition is uncommon in young dogs, with the exception of Rottweilers. If a cruciate rupture occurs in other breeds of young dogs, it is usually secondary to trauma, such as sudden hyperextension of the knee. Occasionally, there is a fracture of the origin or insertion site of the cruciate ligament. Common breeds affected with the degenerative form of CrCL are the Akita, Labrador Retriever, Mastiff, Rottweiler, Staffordshire Terrier, English Bulldog, Boxer, St Bernard, Chesapeake Bay Retriever, Giant Schnauzer, and Bouvier des Flanders. Dogs with “post-legged” conformation are often affected, possibly because of abnormal forces acting on the ligament. Diagnosis is based on clinical signs including joint pain, joint swelling, a firm swelling on the inside of the joint, the presence of a clicking sensation of the joint, and abnormal motion of the knee during manipulation (drawer sign). Surgical treatment is recommended in dogs with CrCL rupture because of the development of arthritis and the possibility of torn knee cartilage. There are several accepted techniques to stabilize the CrCL, the most recent of which is the tibial plateau leveling osteotomy.
Idiopathic Causes of Joint AND Leg Problems in Growing Dogs
Two common idiopathic causes of lameness in the forelimb and hind limb are panosteitis and hypertrophic osteodystrophy (HOD).12,17,18 These two diseases are labeled as idiopathic because their causes are unknown at this time. However, rapidly growing dogs receiving high amounts of energy and calcium appear to be predisposed to both conditions.
Panosteitis is fairly common and can affect the midportion of any of the long bones (femur, humerus, etc).12,18 It has been reported in many breeds and in particular, German Shepherd Dogs and Basset Hounds. It has been suggested that panosteitis is associated with viral or bacterial infections, stress, metabolic abnormalities, vascular abnormalities, allergic or immune-mediated diseases, parasitism, and possibly genetic causes. The lameness may shift to other legs and the dog usually shows pain when the affected long bones are examined. Radiographs may show patchy areas of increased density on the affected bones. Panosteitis is a self-limiting disease that typically lasts several days to weeks. Animals are usually given supportive care for pain.
Hypertrophic osteodystrophy is not a common disease, but is seen in large and giant breed dogs, especially Great Danes.17 The disease is characterized by inflammation and actual death of bone tissue with secondary microfractures of the bone around the growth plate. It is most common in the radius and ulna, and is also seen in the tibia and fibula. The ends of the affected long bones are painful; the dog may have a high fever and stop eating and drinking. Diagnosis is made by clinical signs and radiographs. This disease may be self-limiting, lasting several days to months. Unlike panosteitis, severe cases can have a poor prognosis with systemic concurrent illness and long term affects on the growth plates, with premature closure of the growth plates and angular limb deformities. Some severely affected dogs may have to be euthanized.
INFECTIOUS CAUSES OF JOINT AND LEG PROBLEMS IN GROWING DOGS
Infectious causes of lameness of the young dog are not very common. Septic arthritis and osteomyelitis can occur in neonatal puppies with severe systemic infections; however, this is uncommon. Young dogs can develop septic arthritis and osteomyelitis with bite wounds, penetrating wounds, and trauma. Tick borne diseases such as Lyme disease, Rocky Mountain Spotted Fever, and Ehrlichiosis, may cause lameness in young dogs, but these diseases are more commonly seen in mature dogs. Fungal diseases, such as blastomycosis, histoplasmosis, and coccidiodiomycosis are seen in some parts of the country where these agents are common.
NUTRITIONAL AND METABOLIC CAUSES OF JOINT AND LEG PROBLEMS IN GROWING DOGS
Many studies have evaluated the affects of nutrition on skeletal development in dogs. Diseases such as OCD and HD are affected by the type and amount of diet fed to growing dogs.6 In general, dogs are more apt to develop these conditions when fed free choice, and when fed diets high in energy and calcium. In fact, several studies have demonstrated that there is a lower incidence of arthritis and other joint related problems when puppies are fed 75% of what they would consume if food was available free choice. Perhaps the best prevention is to breed the best to the best and hope for the best, restrict the amount of food fed to puppies, and feed a commercially available diet formulated for growing large and giant breeds of dogs.
With the advent of well-formulated commercially available diets, diseases such as nutritional secondary hyperparathyroidism (from low calcium, high phosphorous, or inadequate vitamin D in the diet) leading to weak bones, skeletal deformities and pathologic fractures are rarely seen. These diseases typically occur when feeding puppies a diet composed mostly of meat.
Neoplastic Causes of Joint and Leg Problems in Growing Dogs
Neoplasia in young growing dogs is rare. Osteosarcoma has been reported in dogs as young as 6 months of age and affects primarily large and giant breeds. Diagnosis is made by clinical signs, radiographs, and biopsy (microscopic examination) of the area. This cancer is typically seen in sites that are “away from the elbow or toward the knee”. Treatment consists of amputation, chemotherapy, and radiation.
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