Degenerative Joint Diseases

• Degenerative Joint Disease

  Pathological condition involving the degeneration of joints
• Degenerative Joint Diseases

  • Wobbler Syndrome (Horses, dogs)
  • Hip Dysplasia (Dogs)
  • Degeneration/herniation of inter-vertebral disks
  • Osteochondrosis (cows, pigs, chickens)
  • Spondylosis (Bulls, dogs)
  • Arthropathies (All species)
• Cervical Vertebral Stenotic Myelopathy (CVSM)

  Significant condition in horses involving spinal cord compression and ataxia
• Cervical Vertebral Instability

  1. Young horses

  2. Dynamic narrowing of the vertebral canal

  3. Spinal cord compression during neck bending (ventroflexion)

  4. Affects C3-C5 vertebrae
• Cervical Static Stenosis

  1. Older horses

  2. Ligamentum flavum hypertrophy

  3. Dorsal narrowing of the vertebral canal at C5-C7 without requiring neck movement

  4. Affects C5-C7 vertebrae
• CVSM in horses

  • Involves two distinct syndromes with age-specific characteristics
  • Both cause spinal cord compression and resulting in ataxia
• Clinical Signs of CVSM

  • Incoordination and locomotor disturbances
  • Primary degenerative changes in vertebral joints lead to canal narrowing and myelomalacia
• Cervical Spondylomyelopathy

  Abnormalities in the cervical vertebrae causing chronic compression, myelomalacia and gait deficits in dogs
• Cervical Spondylomyelopathy in dogs

  • Most commonly seen in Dobermans, Great Danes and other large breeds
  • Male dogs may be more commonly affected
  • Age of onset is variable, from weeks to years
  • Compression and malacia generally occur at C6-C7
• Intervertebral Disk

  • Except for the atlas (C1) and the axis (C2), all vertebral bodies are united by intervertebral disks
  • Disks have an external fibrous ring (annulus fibrosus) and a central soft tissue (nucleus pulposus)
• Types of Intervertebral Disk Diseases

  • Disk Herniation (prolapse)
  • Disk Explosion
  • Cartilage Embolism
• Disk Herniation (Prolapse)

  • Dorsal protrusion of the nucleus pulposus into the spinal canal causing compressive myelomalacia
  • Degenerated disk material frequently mineralizes
• Fibrocartilagenous Embolism

  Embolism of the nucleus pulposus into spinal meningeal vessels, causing ischemic myelopathy and acute spinal deficits
• Spondylosis


  • Chronic degenerative disease affecting the vertebral joints
  • Lesions include degeneration of intervertebral disks, periosteal stimulation, osteophyte formation, bridging between vertebrae and ankylosis
• Spondylosis


  • Most commonly seen in old bulls, sows and dogs
  • Abnormal mobility of intervertebral joints has been proposed as the primary problem
• Animals affected by Spondylosis

  • Bulls
  • Sows
  • Dogs
• Hip Dysplasia

  • Important clinical problem in dogs and humans (>females)
  • Canine form affects mainly large and giant breeds
  • Thought to be closely related to genetic (polygenic) and environmental factors such as nutrition and rapid growth
• Hip Dysplasia in dogs

  • Affected dogs are normal at birth but radiographic changes can be detected as early as seven weeks
  • Begins with edema and hemorrhage in the teres ligament followed by coxofemoral subluxation
  • Injury to the joint induces fibrillation, eburnation and osteophytes
• Hip Dysplasia also causes degenerative joint disease (DJD) in the pelvic bone
• Hip Dysplasia


  Condition affecting mainly large and giant dog breeds, thought to be related to genetic and environmental factors like nutrition and rapid growth
• Progression of Hip Dysplasia

  1. Edema and hemorrhage in teres ligament

  2. Coxofemoral subluxation

  3. Injury to joint induces fibrillation, eburnation and osteophytes
• Hip Dysplasia


  • Macerated femur showing osteophytes around femoral head and shiny, polished subchondral bone (eburnation)
• Degenerative Joint Disease (DJD)


  Caused by hip dysplasia, leads to changes in pelvic bone
• Pathogenesis of Hip Dysplasia

  • Reduced pelvic muscle mass causes instability and abnormal joint movement
  • Intrinsic defect in hip joint leads to secondary DJD
• Osteoarthropathy/Osteoarthritis/Osteoarthrosis

  Heterogeneous group of non-specific degenerative joint diseases affecting primarily appendicular joints of older animals and humans
• Osteoarthropathy


  • Numerous osteophytes in stifle joint of old animal, may be clinical or incidental finding
• Causes of Osteoarthropathy

  Genetic selection, abnormal skeleton conformation, rich diets, hard floors
• Equine Degenerative Joint Disease

  Important conditions include Ringbone, Spavin, Navicular Disease
• Ringbone


  • Deformation and osteophyte formation in interphalangeal joints, likely from mechanical trauma
• Osteochondrosis/Dyschondroplasia

  Heterogenous group of degenerative joint diseases initiated by abnormal cartilage growth/maturation, affecting cartilage of growth plate and articular epiphyseal complex
• Osteochondrosis


  • Affects dogs, pigs, horses, poultry
  • Changes in dysplastic cartilage not spectacular, but secondary joint/bone changes readily visible
• Etiology of Osteochondrosis

  Unclear, but genetic, biomechanical abnormalities, and toxicosis proposed
• Osteochondrosis


  • Large fissures and partial collapsed articular cartilage in humerus head
• Pathogenesis of Osteochondrosis

  1. Problems with vascular supply to growth plate

  2. Poor capillary penetration causes hypoxia and cartilage retention
• Osteochondrosis

  • Irregular articular cartilage width, abnormal cartilage retention as islands in trabecular bone

  
• Osteochondritis Dissecans (Equine)


  Important joint disease affecting distal femur and tibia of young-adult horses, similar pathogenesis to porcine dyschondroplasia
• Osteochondritis Dissecans

  • Focal loss of cartilage with piece dissected from articular surface
• Tibial Dyschondroplasia (Poultry)


  Important bone disease of rapidly growing broilers, related to failure of capillary invasion into proliferating cartilage
• Tibial Dyschondroplasia


  • Abnormal thickening and retention of cartilage in tibias, can become necrotic
• Degenerative joint diseases like tibial dyschondroplasia are "man-made" due to selection for rapid growth