Diseases of the Musculoskeletal System

1. Diseases of the Musculoskeletal System Casey Conway & Jeannie Stall, R.V.T. Credits: A. Summers ClipArt vet.upenn.edu Justanimal.com

2. The Musculoskeletal System • Movement and shape in animals • System of pulleys • Disruption: • Trauma • Degenerative dz • Inflammation • Poor conformation • Neoplasia

3. Long-Bone Fractures 75% occur from HBC Indirect violence, bone dz., repeated stress Open or closed Simple or comminuted Stable or unstable Quickly assess patient, tx shock, etc. Stabilize (bandages,etc), care when moving

4. Long-Bone Fractures • Clin. Signs • Hx Trauma, Pain, Lameness, swelling • Dx • X-rays, 2 views , opposite limb • Tx – reduction and fixation asap if stable • Splints, casts, intramedullary pins, bone plates , external fixators

5. Fractures

6. Cruciate Ligament Injury • Anterior and posterior cruciate ligament • Stabilize the stifle joint • Rupture of the cranial cruciate ligament possibly the most common injury to the stifle of the dog and major cause of DJD • May rupture, or may tear • Middle-age, obese, inactive, or athletic

7. Cruciate Ligament Injury • Clinical Signs • Non-wt bearing on rear leg – pain • Tibia rotates internally when bears wt • If recent – swelling • Acute with onset • Dx - Cranial drawer movement • Tibial compression test • X-rays

8. Cruciate Ligament Injury Tx – Surgical stabilization of the stifle joint Damaged tissue must be removed Restricted exercise post-op then gradually increase exercise Watch opposite stifle for rupture/dz Nsaid therapy for arthritis/DJD in sx joint

9. Patellar Luxations • Medial Luxation • Toy, min, large breeds • Traumatic luxations – any breed • Lateral Luxation • Toy, min breeds • Large giant breeds • Palpation and x-rays • Surgical correction and extensive rehab.

10. Hip Dysplasia-- “Ball & Socket” • Acetabular- most cases (Socket) • Excessive slope of the dorsal rim of the acetabulum, failure of the femoral head to press correctly into the developing cup (damage to the dorsal rim), painful, unstable joint. • Femoral ( Ball) • Femoral neck is shortened, dec. coverage by acetabular rim. Joint lacks support from acet., damage and instability.

11. Hip Dysplasia • Clinical Signs • Vary with age. Young 5-8 mo. Mature w/chronic dz • Difficulty rising, stiffness that goes away • Pain on palpation of dorsal pelvic area • Lameness, waddling gait, young reluct. to stand • Dx – x-rays! • OFA 7 grades • OFA Cert. 2yr– under anesthesia

12. Hip Dysplasia • Tx –Conservative • Moderate exercise • Wt control • Nsaids, steroids • Nutriceuticals ( Glucosamine/Chondroitin) • Surgical • FHO (Femoral Head Ostectomy) • Total hip replacement • Pelvic osteotomy

13. Hip Dysplasia

14. L-C-P Disease (Avascular Necrosis) a.k.a.-- Legg-Calve-Perthes dz. Small-breed dogs, unknown cause Femoral head and neck necrosis X-rays, surgical removal of femoral head and neck Early, active use of limb post-op Genetic predisposition may exist Animals may have both hips involved

15. Osteochondrosis Dissecans Degeneration or necrosis of bone and cartilage followed by reossification Lameness in lg-breed dogs (3-18mo) X-rays Rest and wt control Surgically remove the cartilage flap/mice May have a hereditary component

16. Osteochondrosis Dissecans

17. Panosteitis • Intermittent lameness – shift from leg to leg • Med to lg breed dog – German Shep • Cause unknown, viral – self- limiting • Clincal signs: Anorexia, fever, wt. loss, reluctance to move • Dx: Pain on deep palp., X-rays • Tx: Analgesic, Anti-inflammatory drugs • Recur, not seen over 2 yr old

18. Luxations Secondary to trauma, tearing of joint capsule and round ligament X-rays, closed reduction, open reduction Slings: hip=Ehmer shoulder=Velpeau to stabilize joint then limit exercise Surgery may be necessary Osteoarthritis may develop in that joint

20. Inflammatory Myopathies • Bacterial myositis, rarely occurring • After bite wound or surgical procedure • Staphylococcus and Clostridia spp. • Protozoalmyositis • Cysts form within the muscle of toxoplasmosis + cats, • rupture or immune response results in clin. signs of muscle hyperesthesia • (hypersensitivity to stimulation)

21. Immune-Mediated Myopathies • Polymyositis – dogs and cats, weakness, hyperesthesia, fever, megaesophagus, muscle atrophy. Dx: Biopsy Tx: Pred. • Masticatory muscle myositis - muscle contains special fiber that has antigenic properties possibly shared with bact. Infections elsewhere may incite an immune response that affects these fibers. Swollen, painful, atrophy and fibrose. Glucocorticoids.

22. Tumors of Bone • Dogs: 8000 cases/ yr - 85-90% involve osteosarcoma • 90% of all animals dx with bone cancer die despite treatment • Primary bone cancer in cats is less common • 90% of bone cancers in cats are osteosarcomas • Survival rates after amputation appear to be better for cats than those for dogs

23. Tumors of the Bone • Clinical signs: Lameness, wt. loss, pain, swelling • Dx: x-rays, biopsy, chest x-rays (metastasis) • Tx: Amputation, follow-up with medication. • Radiation therapy for pain control • No recommended drug therapies exist for cats • Bone cancer is fatal • 12 mo with aggressive trt. • Drug therapy is expensive

24. Tumors of the Bone

25. Subsolar Bruising (Corns) • Trauma to the sole w/subsequent hemorrhage between the sensitive and insensitive soles • Acute onset of lameness • Bruises are often bilateral • Sole pain is evident with hoof testers • See the bruise • Proper shoeing/trimming – Nsaids Prevented by proper foot care

26. Hoof Abscess • Acute, severe lameness • Foreign body penetration into the hoof – bact • Heat in foot, coronary band • +/- palmar digital pulse • +/- fetlock and pastern swelling • Localized pain with hoof testers • Dx: visualize draining tract • Sometimes x-ray

27. Hoof Abscess Tx: Localize pain and pare out abscess Epsom salt soaks +/- drawing agent (Ichthammol) Abx usually not indicated, unless kept in dirty unsanitary conditions Be aware of tetanus !! Routine prophylaxis via annual vaccinations

28. Navicular Syndrome • QH, TB, Warmblood • 6-8 yr, older • Inflammation and erosion of navicular bone • Clinical signs: chronic, bilateral lameness • Lameness may be intermittent • Pointing, pain over frog with testers • Dx: • nerve blocks • X-rays

29. Navicular Syndrome • Tx: Nsaids (Non-steroidal anti-inflammatory drugs) -can cause gastric ulceration • Correct hoof imbalance & maintain proper hoof care • Support heels • Surgery

30. Thrush • Bacterial infection of sulci of frog • Wet, dirty conditions, feet not properly maintained • Foul-smelling black discharge • Usually not lame unless severe • Clean feet, remove necrotic tissue • Apply topical astringents • Easily prevented, daily management

31. Fractures Pastern Chip Fractures Proximal Sesamoid Fracture Athletic performance X-rays Surgery / arthroscopic repair Extensive recovery

32. Bucked Shins • New bone production on the cannon bone • 2 yo TB – sudden onset of hard training • Tearing of periosteum – new bone deposition • Forelimbs, bilateral, lameness • Hard, warm, painful swelling on dorsal aspect of cannon • REST, Nsaids, decrease high-speed training • Prevent by modifying training regimen

33. Laminitis Inflammation, avascular necrosis of the sensitive laminae of the hoof Grazing lush pastures Grain overload Metritis/retained placenta Excessive weight bearing on alternate (supportive) limb

34. Laminitis • Occurs when an insult causes blood to bypass dermal laminae via shunts • Possibly due to endotoxins • Extreme vasoconstriction, lack of blood supply causes sensitive laminae to die • Sensitive laminae separate from insensitive laminae and the coffin bone rotates away from the hoof wall, because of the pull of the deep digital flexor tendon.

35. Laminitis

36. Laminitis • Clinical Signs • Bounding pulses in the palmar digital arteries • Hooves may feel warm • “Saw-horse” stance • Pain over toe with testers • Dx: Lateral x-rays • May show rotation of the coffin bone

37. Laminitis • Treatment • Correct underlying/predisposing factors • Bute for pain • Banamine to bind endotoxins • Cold water hose • Shoeing with proper padding • Elevate heels • Deep bedding • Isoxuprine • Acepromazine for vasodilation • Nitroglycerine around coronary bands

38. Laminitis in Sheep and Goats Lush pastures and high-concentrate feeds Systemic illness can predispose C/S: Lameness, warm feet, recumbent DX: C/S, x-rays Tx: Nsaids, tx primary underlying cause Can be prevented Slowly increase feed and or turnout time

39. White Muscle Disease • Nutritional Muscular Dystrophy • Lack of selenium in the diet • Antioxidant, protects cell membranes from damage by free radicals • Cardiac form: dyspnea, recumbancy, tachycardia • Skeletal muscle form: stiff gait, muscle tremors while standing, hunched appearance, dysphagia

40. White Muscle Disease • Dx: • Lab results and whole-blood selenium concentrations from herd • Tx: • Injection of vit E/selenium • Avoid stress/exertion • Many areas of US are selenium deficient – can supplement – but careful not to create toxicity

41. Hip dysplasia--bilateral