Ch 69 Dysplasia, Dysostoses, HOD, Panosteitis, capital epiphysis, aseptic necrosis + metabolic

Question 1

What are the 2 broad categories of constitutional bone and cartilage diseases?

Answer 1

• Osteochondrodysplasias (developmental disorder of chondro-osseous tissue characterised by abnormal endochondral and/or intramembranous ossification
• Dysostoses (Malformation of individual bones, diseases of mesenchymal bone formation)

Question 2

List the two broad categories of dwarfism and some of their respective causes

Answer 2

Proportional - Endocrine, metabolic, polysystemic diseases
Disproportionate - Osteochondrodysplasias and nutritional diseases

Question 3

What hormones should be tested as a part of a work up of dwarfism?

Answer 3

T4 and TSH
GH
IGF-1

Question 4

What are the main classifications of growth retardation?

Answer 4

Osteochondrodysplasia
Endocrinopathy (GH, T4, DM)
Congenital disorders of cell metabolism (lipid/glycogen storage disease)
Nutritional deficiency
Chronic inflammation (immunodeficiency, intestinal parasites)
Congenital or acquired major organ failure or insufficiency

Question 5

What are the only genetic tests available for osteochondrodysplasia?

Answer 5

Mucopolysaccharidosis
Osteogenesis imperfecta

Question 6

What are dystoses?
What are the 2 broad categories?

Answer 6

Dystoses are a group of bone dysmorphologies characterised by the abnormal development of individual bones or parts of bones
- Failure of mesenchymal bone model (anlagen) to form
- Failure f model to transform into cartilage
- Or failure of cartilage to transform into bone

Broad categories:
- Axial (hemivertebrae, block vertebrae etc)
- Appendicular

Question 7

What are the reported forms of appendicular dystoses?

Answer 7

• Amelia = absense of one or more limbs
• Hemimelia = Complete or partial absense of one of more bones
• Dimelia = duplications of part or all of a limb
• Ectrodactyly = Digital cleft extending between metacarpal bones
• Polydactyly = Presense of one or more extra digits
• Syndactyly = Lack of differentiation between 2 or more digits

Question 8

How is hemimelia further classified?

Answer 8

• Terminal - If all or some of the bones distal oto a point are absent
• Intercalary - Bones proximal and distal to the absent bone are present
• Transverse - Complete absense of one or more bones across the limbs width
• Longitudinal - Bones along the preaxial (medial) or postaxial (lateral) side of the limb

Question 9

In what breeds is polydactyly inherited?

Answer 9

St Bernards and Collies (recessive)
Cats (dominant)

Question 10

How can syndactyly be further classified?

Answer 10

Simple = Interconnection consists of skin and fibrous tissue only
Complex = Both soft tissues and bones are fuses
Complete = Digits fused throughout entire length
Incomplete = Only partial fusion
Complicated complex syndactyly = Asscoaited with other defects
Uncomplicated complex syndactyly = No other defects

Question 11

What is hypertrophic osteodystrophy (metaphyseal osteopathy)?

between 2 and 6 months of age

Answer 11

A developmental bone disease of young, rapidly growing dogs causing a zone of disrupted trabeculae in the metaphysis immediatedly adjacent to the physis

aetiology of metaphyseal osteopathy remains unknown > possible genetic predisposition, immune-mediated disease as affected dogs have a cytokine profile
similar to that of children with autoinflammatory bone conditions

Histopathology: symmetrical, suppurative sterile osteomyelitis, periosteal proliferation and increase in osteoclast numbers

Question 12

metaphyseal osteopathy
What breeds are overrepresented?

Answer 12

Breeds: Weimeraners, Great Danes, Chesapeake Bay Retrievers, Irish Setters, Boxers, GSDs, Goldens, Labs

Question 13

Differential diagnosis includes

Answer 13

• secondary nutritional hyperparathyroidism,
• septic polyarthritis,
• trauma,
• retained cartilaginous cores,
• hypertrophic osteopathy

Question 14

What bones are most commonly effected by HOD?
What are the classical radiographic signs?

Answer 14

Most commonly distal radius, ulna or tibia
Radiographic signs:
- Lucent line the the metaphysis parallel to narrow area of increased radiodensity immediately adjacent to the physis
- Enlargement of metaphysis “flare”
- Irregular widening of growth plate

Double physis

Question 15

What factors have been shown to effect outcome of Weimeraners with HOD?

Answer 15

Treatment with corticosteroids more successful than NSAIDs (100% vs 45.5% remission within 48hr)
Those with effetive litter-mates are more likely to relapse

• Optimal treatment has not been determined
• Outcome is generally good; however, relapse episodes can be seen until growth plate closure

Question 16

Presenting signs and clinical outcome in
dogs with metaphyseal osteopathy: 39
cases (2009–2018)
Robertson 2023

Answer 16

retrospective review
more males
pyrexia (34 of 39), lethargy (32 of 39), pain (30 of 39), and being non-ambulatory (17 of 39)
several require hospitalisation for Tx
relapse in 8/25 cases before reaching skeletal maturity
4/25 developed future immune-mediated conditions

Question 17

panosteotis

Answer 17

• self-limiting inflammatory disease of the bone marrow of long bones.
• between 5 and 12 months of age; however, age can vary from 2 months to 5 years

Question 18

What small breed dogs have been overrepresented with panosteitis?

Answer 18

Miniature Schnauzers and Scottish Terriers

Question 19

What is thought the be the pathogenesis of panosteitis?

Answer 19

Vascular congestion and increased intramedullary pressure of 25 - 54mmHg (Normal 6-24), potentially due to protein accumulation

origin of panosteitis is poorly understood

Question 20

What is the ratio of forelimb to hindlimb involvement for panosteitis?
What are the typical radiographic signs?

Answer 20

4:1 FL:HL (ulna 42%, radius 25%, humerus 14%, femur 11%, tibia 8%)
Increased medullay opacity with granular pattern or with loss of normal trabecular pattern
Periosteal bone formation (laminar or smooth)
radiographs may be normal in early dz

Question 21

What unique treatment has been reported for panosteitis?

Answer 21

Benzopyron - a proteolytic substance
Resulted in normalisation of intramedullar pressure and remission within days

Question 22

What is craniomandibular osteopathy?
What breeds are overrepresented?

Answer 22

• Unilateral or bilateral symmetric irregular osseous proliferation of mostly the mandibles and/or tympanic bullae.
• Temporal bones or other skull or long bones may also be affected.
• Osteoclastic resorption of lamellar bone, followed by the presense of primitive bone that expands beyond the periosteum
• Normal bone marrow is replaced by a highly vascular fibrous-type stroma.
• borders of the lesions are invaded by inflammatory cells, and adjacent connective tissue and muscle fibers are destroyed

Breeds: Cairn Terriers, WHWT, Scottish Terriers

younger than 6 months highest risk, Most <12 months

Question 23

CS of caniomandibular osteopathy

Answer 23

difficulty eating
inability to open the mouth
salivation,
weight loss, inappetence to anorexia
enlargement or irregularity of the mandibles
enlargement/fusion of the angular processes of the mandible and tympanic bulla

Craniomandibular osteopathy of the ulnas with secondary bilateral valgus deformity has been reported in a West Highland White Terrier

Question 24

What is the outcome of surgical treatment of CMO?

Answer 24

Lesions usually recur within 3 weeks, not generally recommended

Bilateral rostral mandibulectomy has been used as a salvage procedure

Over time, lesions usually regress either completely or patially > may become self-limiting when the dog is approximately 11 to 13 months of age

Question 25

Retained Ulnar Cartilaginous Core

Answer 25

- cones of growth plate cartilage that project from the distal ulnar growth plate into the distal metaphysis - consist of viable hypertrophic chondrocytes - represent failure of the growth plate cartilage to convert to metaphyseal bone. - predominantly in large to giant, immature dogs antebrachial deformity: reduced ulnar length growth, cranial bowing of the radius, rotation and valgus deviation of the manus, and subluxation of the carpal and elbow joints may be seen

Question 26

Legg-Calve-Perthes disease

Answer 26

- avascular necrosis of the femoral head - noninflammatory local ischemia with subsequent deformation of the femoral head and neck - necrosis of the trabeculae of the femoral head > loading of the affected hip causes collapse of the epiphyseal subchondral bone - epiphysis and metaphysis revascularize, and new bone is formed > femoral head will be partially or completely malformed | A flexed ventrodorsal view of the hip joint (frog view)

Question 27

What breeds are predisposed to Legg-Calve-Perthes disease? How often is it bilateral?

Answer 27

Toy breeds (Min Poodles) and WHWT and Manchester Terriers - Bilateral in 12 - 16.5%

Question 28

Legg-Calve-Perthes disease

Answer 28

cause not well understood proposed: - anatomic conformation, - increased intracapsular pressure, - infarction of the femoral head, - hormonal influences - hereditary factors Tx: surgical treatment (femoral head and neck excision or total hip replacement) is the preferred

Question 29

What animals are overrepresented for slipped capital physis? How often is it bilateral? possible contributing factors (4):

Answer 29

Male, neutered overweight cats with delayed physeal closure Bilateral 24 - 38% - genetics, - obesity, - endocrine imbalances, - neutering and sex

Question 30

Slipped Capital Femoral Epiphysis

Answer 30

- slow progressive displacement of the proximal femoral metaphysis from the capital femoral epiphysis through the growth plate - Growth plate changes = loss of the normal columnar arrangement of chondrocytes, chondrodyte clusters, physeal clefts, and thickened growth plates (whether these changes are the cause or the effect) - Physeal widening = first radiological signs, the dysplastic physis is then no longer able to resist mechanical stress > resorption and sclerosis of the femoral neck may be seen | Tx: FHO/THR

Question 31

What are multiple cartilaginous exostoses? How do they differ in dogs and cats?

Answer 31

- Benign bone disease characterised by multiple cartilage capped bone protuberances arising from surfaces of any bone developed by endochondral ossification - exostoses develop via endochondral ossification, originating from growth plate chondrocytes that are displaced outside the growth plate - Dogs - Young, growing puppies during endochondral ossification, tend to stop when fully grown, found in the metaphyseal portion of the bone - Cats - Develop after skeletal maturity *can undergo malignant transformation to chondrosarcoma or osteosarcoma*

Question 32

What is the hypothesised cause of multiple cartilaginous exostoses? | familial tendencies have been reported

Answer 32

Failure of the perichondrial ring of Lacroix (peripheral constraint of the growth plate)

Question 33

CS, imaging, DDX (6) and Tx for multiple cartilaginous exostoses

Answer 33

- Clinical signs associated with larger lesions range from interference with motion to pain and clinical signs secondary to tendon, ligament, vessel, and spinal cord compression. - most frequently affects vertebra, ribs, and long bones - CT: large, irregular soft tissue and mineral-attenuating masses - Continued growth of the exostosis after the animal matures is highly suggestive of a malignant transformation Differential diagnoses: - osteomyelitis, - neoplasia, - disseminated idiopathic skeletal hyperostosis, - hypervitaminosis A, - skeletal coccidioidomycosis - bone cyst. Tx: - Surgical excision may be required to combat pain, restore function, or improve cosmesis - periodic radiographic monitoring recommended if not needed to be removed

Question 34

Swimmer Syndrome

Answer 34

- Clinical signs are apparent in the first 1 to 2 weeks of birth - cause of the decreased muscle tone is unknown, but environmental conditions such as confinement in an area with poor traction and genetics may be involved - if treatment is instituted within the first 3 to 4 weeks of birth, the prognosis can be good. - Treatment recommendations include application of hobbles and physical rehabilitation.

Question 35

Puppy Carpal Laxity Syndrome

Answer 35

- carpal hyperextension or carpal hypoextension - unilateral or bilateral. - present between 6 and 16 weeks of age - Conservative treatment: exercise, splinting, and change to an adult diet are sufficient for most mild cases - study of 43 puppies, 65.11% recovered within 2 weeks

Question 36

What is the normal standing carpal angle in puppies? What surgical options are there for puppy carpal laxity syndrome if conservative management fails?

Answer 36

Normal Angle 180-190 degrees Surgical options: - Tenotomy - Arthrodesis

Question 37

Metabolic bone diseases (7)

Answer 37

- primary hyperparathyroidism, - nutritional or renal secondary hyperparathyroidism, - hypovitaminosis D (rickets), - hypervitaminosis D, - hypovitaminosis A, - hypervitaminosis A - hypovitaminosis E Dogs and cats with generalized osteopenia, brittle bones, pathologic fractures, limb deformities, and/or excessive new bone formation (hypervitaminosis A) should be evaluated for metabolic bone disease. Treatment is aimed at correction of the underlying abnormality

Question 38

What is hypertrophic osteopathy? | maries dz

Answer 38

Periosteal reaction of the distal extremities result of increased peripheral blood flow and vascular congestion in the periosteum due to neuronal stimulation from usually pulmonary neoplasia (primary or metastatic) > secondary manifestation of a primary condition possibly mediated by vagal - distal extremities and long bones - bilaterally symmetrical lesions and involve all four distal limbs - 6 months to 15 years, mean 8.7 years - clinical signs of hypertrophic osteopathy regress rapidly after surgical removal of the primary thoracic lesion - lameness, skin over the distal joints and extremities appears firm and taut - rads: palisade bone formation - Early in the disease, soft tissue swelling of the extremities with little to no bone production Differential diagnoses - osteomyelitis, - degenerative joint disease, - neoplasia, - hypertrophic osteodystrophy, - hypervitaminosis A (feline), - multiple cartilaginous exostosis - panosteitis tx: managing the primary problem and usually consists of surgical resection of the mass tumor recurrence or metastasis may occur, and the osteopathy can return

Question 39

What is disseminated idiopathic skeletal hyperostoses?

Answer 39

DISH - Spinal and extraspinal manifestations of heavy bone formation, most commonly along ventral longitudinal ligament Boxers overrepresented ddx spondylosis deformans, multiple cartilaginous exostosis, hypervitaminosis A (cats), IVDD - Severely affected patients may have difficulty moving - extraspinal hyperostosis at any site of ligament and tendon attachments - some asymtomatic - tx: variable, spinal decompression if indicated, prognosis depends on the size and location of the lesions

Question 40

4 out 5 criteria is thought to be sufficient for a diagnosis of disseminated idiopathic skeletal hyperostosis:

Answer 40

(1) continuous or “flowing” calcification and ossification of at least three contiguous vertebral bodies (2) relative preservation of intervertebral disc width in involved areas (3) periarticular osteophytes surrounding the zygapophyseal joints; (4) formation of pseudoarthrosis between the bases of spinous processes (5) periarticular osteophytes of axial and peripheral skeleton

Question 41

Bone cyst | prognosis is good to excellent in most cases

Answer 41

Simple bone cysts - fluid-filled cavities, lined by fibrous connective tissue - callus formation may be evident in areas of injury or fracture. - monostotic (involving only one bone) or polyostotic (involving more than one bone). - metaphyseal venous obstruction with secondary osteolysis has been proposed Subchondral cysts - adjacent to a synovial membrane insertion - associated with osteochondrosis. cause discomfort only when they are fairly large. Bone cysts are often found in the extremities, but any bone can be involved Radiographs: expansile, locally aggressive lucent lesion with little or no periosteal reaction. Check all bones. scrutinized for pathologic fractures fine needle aspirates or biopsy Tx: conservative (if static, asymptomatic) vs drainage, curettage, placement of cancellous bone graft, radiation treatment, excision, fixation.

Question 42

What are the three main classifications of bone cysts? What breed is predisposed to polyostotic cysts?

Answer 42

Cystic (simple unicameral) Aneurysmal Subchondral Dobermans predisposed to polyostotic cysts

Question 43

What breeds are overrepresented for acute caudal myopathy? | limp tail

Answer 43

Pointers Labrador Retrievers - recent hunting or swimming - tail is often flaccid, Nociception is present - differential diagnosis neurolgical dz, pelvic disease (fracture, neoplasia), prostatic disease - spontaneously recover within a few days to weeks

Question 44

What is the surgical option for recurrent iliopsoas injury?

Answer 44

Tenomyectomy - acute and chronic pelvic limb lameness - shortened stride, - positive iliopsoas muscle maneuver test (hip joint in flexion, simultaneous internal rotation and extension of the affected limb) pain lesser trochanter - Concurrent orthopedic and neurologic diseases such as hip dysplasia, cranial cruciate ligament injury, lumbosacral disease common - Ultrasonography - conservative (rest, pyhsio, nsaid)