2. DISEASES OF THE MUSCULOSKELETAL SYSTEM
PART 3
Chapter 7

3. LEGG-CALVE-PERTHES DISEASE aka AVASCULAR NECROSIS of the FEMORAL HEAD
YOUNG, SMALL BREEED DOGS
Noninflammatory necrosis of the femoral head and neck. Unknown cause, thought to be vascular compression with hormone activity.

4. LEGG-CALVE-PERTHES DISEASE
Not sure if it just develops or due to trauma. Loss of blood flow which results in necrosis.
Considered a developmental disorder but could also occur due to trauma

5. LEGG-CALVE-PERTHES DISEASE
Clinical signs
Pain in the hip
Atrophy of the muscles of the affected limb
Gradual onset of lameness
Chewing at the hip and flank area
Usually young dogs 5-8months
Treatment consist of surgery!
Atrophy: muscle becomes much smaller.

6. LEGG-CALVE-PERTHES DISEASE: TREATMENT
Remove the head of the femur and part of the neck, depending how bad it is.
FEMORAL HEAD AND NECK EXCISION (FHNE) aka FEMORAL HEAD OSTECTOMY (FHO)

7. LEGG-CALVE-PERTHES DISEASE: TREATMENT
CLIENT INFO
Post-operative treatment requires early and active use of the limb as soon as 2 weeks after surgery
Exercise and passive range-of-motion exercises should be done daily
Animals may have both hips involved – surgeon is likely to separate procedures by 8-10 weeks
Therapy for patients: hydrotherapy

8. DEGENERATIVE DISORDERS: OSTEOCHONDROSIS DISSECANS
OCD
Disease of the cartilage that can affect multiple joints

9. OSTEOCHONDROSIS DISSECANS
Bone does not fully grow (ossify) which results in thickened articular cartilage- because normally cartilage should turn into bone. This causes cracks in the articular cartilage and is very painful (cartilage is more prone to injury)
FAILURE OF THE LOWER LAYERS OF ARTICULAR CARTILAGE TO MATURE INTO
BONE RESULTS IN THICKENED CARTILAGE THAT IS PRONE TO INJURY

10. OSTEOCHONDROSIS DISSECANS
Failure of the articular cartilage to become cemented to underlying bone, together with constant trauma during exercise, results in formation of a non-healing flap or joint mouse
This disorder can occur in several joints
Shoulder
Stifle
Hock
Elbow
CLINICAL SIGNS
Lameness in young, large breed dogs
Seen more in the scapulohumeral joint: shoulder. Believed to be hereditary.
The cartilage flap is what causes the bones to rub together causing pain.
A joint mouse is a loose piece of cartilage or bone tissue that floats freely through the joint

11. OSTEOCHONDROSIS DISSECANS
CARTILAGE FLAP OF THE SCAPULOHUMERAL
JOINT WHICH IS THE MOST COMMON LOCATION

12. DIAGNOSIS

13. OSTEOCHONDRITIS DISSECANS
Joint mouse is a fragment that roams freely within the joint.
JOINT MOUSE IN THE STIFLE JOINT

14. OSTEOCHONDROSIS DISSECANS: TREATMENT
SURGICAL REMOVAL OF THE FLAP OR JOINT MOUSE via ARTHROSCOPY
ALMOST IMMEDIATE RETURN TO NORMAL FUNCTION
The surgery to remove the flap or joint mouse
This is common in large breeds. If p is lame then surgery may need to be done. Crate rest and weight control are an option in early stages, but once completely lame, surgery is best.
Less likely to return.

15. INFLAMMATORY CONDITIONS: PANOSTEITIS
Inflammation of the medullary marrow of long bones: Ulna, humerus, radius, femur and tibia seemed to be the most affected bones.
Suspect: viral infections, genetics, metabolic disease, or hormonal issues (really the cause is unknown)
LARGE, MEDIUM BREEDS AT A YOUNG AGE 6-8 MONTHS
CAUSE: UNKNOWN, BUT THERE ARE MANY SUSPECTED CONTRIBUTORS

16. PANOSTEITIS INFLAMMATION IN THE MARROW
PELVIS
LESIONS OF PANOSTEITIS
FEMUR
INFLAMMATION IN THE MARROW
CAVITIES OF LONG BONES THAT LEADS
TO PAIN, INTERMIITENT LAMENESS, AND FEVER
Anorexia
Wt. loss
Reluctant to move
Signs are usually acute, not associated with trauma. P will sometimes shift back and fourth on each limb. Most common in German Shepherds.
Causes medullary cavity to become inflamed (looks much larger on radiographs)

17. PANOSTEITIS INCREASED MEDULLARY OPACITY Affects bone marrow.
Medullary: inner portion of the bone
Opacity: the bone looks larger

18. TREATMENT OF PANOSTEITIS INCLUDES NSAIDS AND CAGE REST
THIS DISEASE IS SELF-LIMITING AND HAS A GOOD PROGNOSIS!

19. TRAUMA: LUXATIONS
Luxation's involve tearing of the joint capsule and round ligament (joint is out of its normal position).
HX OF TRAUMA, ACUTE LAMENESS, NON WEIGHT BEARING, POSSIBLE
SWELLING OVER THE AFFECTED JOINT

20. COXOFEMORAL LUXATIONS
Craniodorsal: leg will look shortened, stifle will rotate outwards and the hock will rotate inwards.
Craniocaudal: rare. Stifle rotates inward and hock rotates outwards.
Ventral: rare. Limb looks longer.
CRANIODORSAL LUXATION IS THE
MOST COMMON TYPE

21. LUXATIONS
TREATMENT
Closed reduction: femoral head is replaced back into the acetabulum under anesthesia
Open reduction: femoral head is surgically replaced into the acetabulum and the soft tissue structures are used to secure the reduction.
Radiographs will be done to rule out fractures. With closed reduction, the femoral head can pop back out of place. With an open and closed reduction, a sling will need to be used to hold the limb in place for 7-10 days.
Closed reduction coxofemoral luxation (DOVE) video

22. STABILIZING REDUCED LUXATIONS
Ehmer sling: canine (DOVE) video
THE EHMER SLING IS USED AFTER CLOSED AND OPENED REDUCTION OF THE LUXATED
HIP JOINT; THE DOG SHOULD BE CONFINED FOR 7-10 DAYS

23. ELBOW LUXATION
IT IS CRITICAL TO ALWAYS PERFORM 2 RADIOGRAPHS THAT ARE AT 90∘TO EACH OTHER
THESE ARE CALLED ORTHOGONAL VIEWS
THIS IS TRUE FOR ALL RADIOGRAPHS & NOT ONLY ORTHOPEDICS
Orthogonal refers to having two views to look at it.

24. STABILIZING REDUCED LUXATIONS
THIS VELPEAU SLING IS USED TO PREVENT WEIGHT BEARING ON THE FORELIMB

25. NEOPLASIA OF THE BONE MOST COMMON IN LARGE BREED
MALE DOGS OLDER THAN 7 YRS OF
AGE
85-90% involve osteosarcoma

26. NEOPLASIA 85%-90% OF BONE CANCER IN DOGS IS OSTEOSARCOMA
Osteosarcoma is a type of cancer that produces immature bone. It is the most common type of cancer that arises in bones, and it is usually found at the end of long bones
85%-90% OF BONE CANCER IN DOGS IS OSTEOSARCOMA
THE DISTAL RADIUS IS THE MOST COMMON LOCATION

27. NEOPLASIA: DIAGNOSIS RADIOGRAPHS AND BIOPSY SHOULD BE PERFORMED TO
OSTEOLYSIS
PROLIFERATION
OF BONE
PERIOSTEAL REACTION
Osteolysis: destruction of bone structure.
Proliferation: bone grows (cancer).
Periosteal reaction: Bone growth due to cancer cells
RADIOGRAPHS AND BIOPSY SHOULD BE PERFORMED TO
CONFIRM DIAGNOSIS

28. NEOPLASIA
We did chest rads on any older animals prior to surgery.
METASTASIS OF OSTEOSARCOMA TO THE LUNGS; THERE IS USUALLY ALREADY
SOME MICROSCOPIC SPREAD OF TUMOR BY THE TIME IT IS DIAGNOSED

29. NEOPLASIA
Sadly, with cancer, even with removal and chemotherapy, if it has spread, they will die from it.
Forequater amputation (DOVE)
AMPUTATION OF THE AFFECTED LIMB ALONG WITH CHEMOTHERAPY IS A COMMON TREATMENT PLAN
SURVIVAL TIME IS ~12 MONTHS EVEN WITH AGGRESSIVE THERAPY

30. MYOPATHIES MYOPATHIES are diseases that affect the muscle
Inflammatory (bacterial, protozoal)
Immune-mediated
Acquired (secondary to other diseases)
Diagnosis is usually made by muscle biopsy and treatment directed toward the primary cause
Inflammatory: after a bite wound or after contaminated surgical procedure (can lead to muscle sensitivity)
Immune-mediated: Polymyositis (inflammation of muscles)
Acquired: feline disease due to low potassium levels

31. IMMUNE-MEDIATED MYOPATHIES: MASTICATORY MUSCLE MYOSITIS (aka atrophic myositis, eosinophilic myositis)
Involves muscles of mastication
Affects their chewing. Trismus: lock jaw
Myositis means inflammation of the muscles that you use to move your body
CLINICAL SIGNS INCLUDE: ELEVATED 3RD EYELIDS, ATROPHY OF THE JAW
MUSCLES, AND INABILITY TO OPEN THE MOUTH (TRISMUS)

32. The treatment of choice is glucocorticoids (steroids).
IMMUNE-MEDIATED MYOPATHIES: MASTICATORY MUSCLE MYOSITIS (aka atrophic myositis, eosinophilic myositis)
The muscles of mastication contain a special type of fiber (2M) that has antigenic properties possibly shared with bacteria.
The treatment of choice is glucocorticoids (steroids).
Has the same antigenic properties as bacteria, so that’s why there is a reaction. Jaw becomes swollen and painful.

33. ACQUIRED MYOPATHIES: FELINE POLYMYOPATHY
HYPOKALEMIA:
CERVICAL VENTROFLEXION OF THE NECK, PERIODIC WEAKNESS, AND MUSCLE PAIN
TREATMENT: Potassium supplementation, diet change
Hypokalemia: low potassium levels in the blood.
Chronic kidney disease, Excessive diarrhea or vomiting, Genetics, although this usually only affects Burmese cats, Unbalanced diet, Excessive urination