Test 3- Bone Flashcards
1
Q
In addition to provide mechanical support and protecting key organs from traumatic injury bone plays an important role
A
In addition to provide mechanical support and protecting key organs from traumatic injury bone plays an important role in Ca homeostasis.
2
Q
“Bones are
A
Bones are dynamic organs undergoing constant remodeling throughout life”
3
Q
Are Diseases of bone diganosed a lot?
A
Diseases of bone are often under-diagnosed
4
Q
Bone is a specialized
A
Bone is a specialized connective tissue consisting of cells embedded within a gel-like substance that becomes mineralized
5
Q
Bone has the property of
A
Bone has the property of marked rigidity and strength whilst retaining some degree of elasticity
6
Q
To accommodate changes related to mechanical stresses and demands on calcium homeostasis bones are
A
To accommodate changes related to mechanical stresses and demands on calcium homeostasis bones are in a dynamic state of growth and resorption throughout life.
7
Q
Like other types of connective tissue bone is composed of
A
Like other types of connective tissue bone is composed of cells and an organic extracellular matrix containing primarily glycoproteins and collagen fibersthis matrix is known as osteoid. Osteoid rapidly undergoes mineralization (by deposition of inorganic salts, mainly calcium hydroapatite (CHAP) crystals, to form bone.
8
Q
The bone matrix also contains a variety of
A
The bone matrix also contains a variety of growth factors which probably play an important role in bone development, modeling and remodeling.
9
Q
Cellular elements of bone
A
• Osteoblasts- produce osteoid, immature cells of bone
- Osteocytes- mature cells of bone
- Lining cells (inactive osteoblasts)
• Osteoclasts- multinucleated cells that reabsorb bone- maintain Ca + metabolism
10
Q
A
pinkish- osteoid
large mulitnucleated cells- osteoclasts that liberate ca into the blood
11
Q
There are two types of bone based on the degree of maturity…
A
- Woven bone: Immature bone present during fetal development and in the early stages of bone repair. Collagen fibers in woven bone are randomly arranged adopting a crisscross (woven) pattern microscopically.
- Lamellar bone: Mature bone. Collagen fibers are arranged in a parallel pattern.
according to the stage of maturation bone(cortical or canellous) could be either woven or lamelluar
12
Q
During fetal life bone formation occurs in 2 ways, both of which involve replacement of connective tissue by bone:
A
- Intramembranous ossification – Occurs within “membranes” of condensed primitive mesenchymal tissue flat bones of the skull ONLY
- Endochondral ossification – Occurs in the majority of bones of the skeleton (limbs, vertebral column, pelvis, base of the skull). Bone develops from a cartilaginous model (hyaline cartilage) that is subsequently replaced by osseous tissue present in the so called ossification centers.
13
Q
epiphyseal plates
A
Endochondral ossification occurs in the ossification centers of immature bones and in the growth plates (epiphyseal plates) of developing bones.
14
Q
Once the growth plates are closed (mature animal),
A
Once the growth plates are closed (mature animal), no further longitudinal growth (resulting in increase length) can occur.
15
Q
A
growth plate
Bottom- begining of mystephosis- spoongy bone
Top- resistin cartilage- chondro cysts are isolated
Proliferative(p) layer
16
Q
Chondrodysplasia
A
Chondrodysplasia (Chondrodysplasia fetalis or disproportionate dwarfism)
Breed-associated, usually hereditary conditions that occur in dogs, cattle and sheep. Membranous appositional growth is normal but interstitial growth of cartilage is abnormal resulting in premature close of growth plates and decrease length of long bones (affects bones that form by endochondral ossification).
Most common in beef breeds (Angus, Hereford). In Dexter cattle, homozygote animals for the Dexter phenotype (Dexter “bulldog” dwarfism) are severely deformed and are usually aborted before 7 months of gestation (lethal form of chondrodysplasia).
17
Q
“Dexter bulldog
A
“Dexter bulldog” – Congenital lethal Chondrodysplasia
Inherited condition of Dexter cattle.
Affected calves are often aborted and exhibit disproportionate dwarfism,
short vertebral column, marked micromelia (shortening of the limbs),
large head with short muzzle, protruding
tongue and large abdominal hernia
18
Q
Chondrodystrophic dog breeds exhibit
A
Chondrodystrophic dog breeds exhibit localized chondrodysplasias involving specific bones.
Daschumonds- Micromelic achondroplasia(very short limbs)
Other brachicephalic chondrodystrophic dog breeds are Bulldogs and Boxers
Basset hound
19
Q
Cervico-vertebral stenotic myelopathy (Wobbler‟s syndrome)
A
- This a localized skeletal dysplasia most common in horses and large breed dog
- It can also be classified as a degenerative joint disease which affects the axial skeleton.
- The syndrome results in dynamic or static compression of the cervical spinal cord (SC) by abnormal cervical vertebrae.
- In the dynamic form sc compression occurs when the neck is flexed; in the static form sc compression occurs no matter what position the neck is in.
Wobbler’s in horses and large breed dogs
20
Q
A
Cervical vertebral stenotic myelopathy
in Doberman
“ski-slope lesions”
21
Q
A
Wobbler Syndrome, horse
static- severe compression of the cervical canal
22
Q
Osteopetrosis
A
Osteopetrosis (petros: rock)
Inherited disease caused by osteoclast failure to reabsorb the primary spongiosa. This failure results in an increased bone density and lack of medullary (bone marrow) spaces.
23
Q
Metaphyseal Dysplasia
A
Osteopetrosis is an heritable condition also known as “Metaphyseal Dysplasia” results in diffuse osteosclerosis (↑ bone density).
Since there is no space for the hematopoietic tissues of the bone marrow to grow, affected animals often present aplastic anemia. Affected bones have an increased susceptibility to fracture. Reported mainly in dogs, sheep, cattle and horses.
- Aplastic anemia
24
Q
A
Osteopetrosis
25
Congential Cortical hyperostosis of pigs
Autosomal recessive inherited condition in pigs.
• Limbs (**primarily the forelimbs)** appear swollen due to excessive deposition of radiating trabeculae on the periostal surface, and blockage of the local lymphatic circulation.
Most affected pigs are born dead or die within hours- lame animals that can not stand
This abnormality has been compared to Caffey‟s disease (infantile cortical hyperostosis) observed in children and monkeys.
26
Localized malformations
Localized malformations
* Limbs (appendicular skeleton)
* Amelia: Absence of a limb(s|)
* Hemimelia: Absence of the distal half of a limb
* Polymelia: Supernumerary limbs
* Phocomelia: Abscense of the proximal portion(s) of a limb(s)
* Micromelia: Abnormally small or short limb(s)
* Syndactylia: Fusion of the digits
* Polydactylia: Supernumerary digits
* Others...
27
Amelia:
Absence of a limb(s|)
28
Hemimelia:
Absence of the distal half of a limb
29
Polymelia:
Supernumerary limbs
30
Phocomelia:
Abscense of the proximal portion(s) of a limb(s)
31
Micromelia:
Abnormally small or short limb(s)
32
Syndactylia:
Fusion of the digits
33
Polydactylia:
Supernumerary digits
34
Lordosis:
Ventral deviation of the vertebral column
35
Kyphosis:
Dorsal deviation of the vertebral column
36
Scoliosis:
Lateral deviation of the vertebral column
37
Kyphoscoliosis:
Dorso-lateral deviation of the vertebral column
38
Dorsal deviation of the spinal column- kyphosis
39
Angular limb deformities
Angular limb deformities – Relatively common in young animals and specially important in horses. In many cases (not all) the origin of the deformity can be traced to an asymmetric lesion in an active growth plate. Characterized by twisting of the bone: lateral (outward) deviation (valgus deformity) or medial (inward deviation (varus deformity) of one or more limbs distal to the affected growth plate or joint. Present at birth or may develop later in life. Causes may include:
- Malposition in utero
- Joint laxity
- Hypothyroidism (congenital goiter)
- Trauma (ischemia or reduced blood supply) - Malnutrition
- Impaired endochondral ossification
40
Carpal Valgus, foal.
41
Metabolic Bone Diseases
• Also referred as osteodystrophies
Result from disturbed bone growth, modeling or remodeling due to either nutritional or hormonal imbalance.
MBD is characterized by failure of production of bone matrix, its mineralization or its maintenance.
42
Metabolic Bone Diseases Etiology
_Nutritional:_ Vitamins C, D, Ca, P, Protein
_Hormonal:_ Parathyroid (PTH), Thyroid (calcitonin),
gonads (estrogens), adrenal problems (corticosteroids).
Disuse: Physical inactivity
Toxic: Lead and fluoride poisoning, hypervitaminosis A etc.
43
Can metabolic bone diseases have more than one etiology?
In a particular individual metabolic bone diseases can have more than one etiology. In addition, different forms of metabolic bone disease (osteodystrophies) can coexist in the same individual.
44
In domestic animals metabolic bone disease caused by nutritional deficiency
In domestic animals metabolic bone disease caused by nutritional deficiency is often caused by deficiency of more than one nutrient.
45
Osteoporosis
Characterized by osteopenia (↓ in the amount of bone tissue). “ there is a ↓ amount of bone but the bone that is present is normal. _Grossly there is a reduction in the thickness of the cortical bone and a ↓ number of trabeculae in the cancellous bone._
46
Osteoporosis Etiology
1. Nutritional
* *Starvation(MOST COMMON)**, Cu deficiency, Vitamin C deficiency.
2. Aging
In humans peak bone mass occurs around the age of 30; there after resorption outpaces bone formation.
3. Disuse
47
Goat, osteoporosis/ osteopenia – Cornell Serous atrophy of bone marrow -Starvation
48
From McGavin: Sheep Osteopenia/ osteoporosis
49
Heifer – starvation Serous atrophy of BM Fat, Cornell Files
osteoporosis- MIGHT BE, but it's hard to diagnosis
50
Rickets
Metabolic bone disease of a complex etiology affecting **young growing animals.**
The basic pathogenesis involves defective calcification of osteoid and defective endochondral ossification.
Etiology is multifactorial but _typically involves vitamin D or phosphorous deficiency._
• **Exposure to sunlight (s**olar ultraviolet radiation is also important).
51
Gross Lesions in Rickets
o Irregular thickening of growth plates with tongues of uncalcified
cartilage extending into the metaphysis
o Widening of growth plates enlarged ends of long bones; **enlargement of costochondral junctions (“rachitic rosary”)**; weight-bearing long bones may become bowed
o Hemorrhages beneath the articular cartilage or in growth plates o Pathological fractures may occur
o At necropsy ribs bend rather than snap
52
Rickets. Dog from India
53
Osteodystrophic (growth- arrest) lines –Rickets-Foal
54
Chicken: Rachitic rosary
55
Osteomalacia
**A disease of grown (adult) animals (closed growth plates).**
Similar pathogenesis to rickets: failure in the mineralization of
osteoid primarily due to vitamin D or P deficiency.
Unmineralized osteoid is resistant to osteoclastic resorption and accumulates in the bone.
Affected animals may exhibit bone pain (shifting lameness), pathologic fractures and deformities such as kyphosis, lordosis and scoliosis.
_Collapse of articular surfaces may occur._
56
Fibrous Osteodystrophy
(osteodystrophia fibrosa; osteitis fibrosa cystica)
Relatively common metabolic bone disease characterized by _extensive bone resorption and replacement by fibrous connective tissue and poorly mineralized immature bone._
* The disease is the result of persistent elevations of _plasma PTH levels (hyperparathyroidism)._
* More common in horses, pigs, dogs and cats. Also seen in reptiles and New World Monkeys.
57
Fibrous Osteodystrophy Mechanism:
Primary Hyperparathyroidism-
Fibrous Osteodystrophy (Basic mechanism: ↓Ca; ↑P= ↑PTH)
Due to primary or secondary hyperparathyroidism.
_Primary Hyperparathyroidism:_
- Usually associated with **functional parathyroid adenomas in dogs.**
- Affected animals exhibit marked hypercalcemia and hypophosphatemia.
- Lesions may include FO; Thyroid C-cell hyperplasia; hypercalcemic nephropathy (nephrocalcinosis) and metastatic mineralization in soft tissues.
58
Secondary Hyperparathyroidism(MORE COMMON)
**1. Nutritional:** Dietary deficiency of Ca; excess dietary P, or deficiency of Vitamin D. In most cases nutritional secondary hyperparathyroidism is the result of ↓Ca or ↑ P in the diet and, with the exception of horses, affects young growing animals.
**2. Renal:** Complex etiology but P retention due to l_oss of glomerular function_ and the inadequate synthesis of 1, 25 _Dihydroxyvitamin D_ (1,25, dihydroxy cholecalciferol, _calcitriol)_ by the kidney play a mayor role.
_Renal osteodystrophy occurs more commonly in the dog._ Bones, especially those of the head become swollen and are firm rather than hard, maxilla and mandible are usually affected. The mandibles may become quite pliable (“rubber jaw”). Teeth are often mobile and malpositioned within the swollen gums and alveolar bone.
59
Fibrous osteodystrophy, Horse. Loss of bone and replacement by fibrous connective tissue.
"Bran disease or Big head"
60
“Rubber jaw” – _Renal Osteodystrophy_, dog Cornell files.
61
Fibrous osteodystrophy
teeth become burried
62
Shih-Tzu, Renal osteodystrophy, Cornell files.
63
fibrous osteodystrophy
teeth are embedded in the proliferative tissue
64
Fibrous Osteodystrophy
- metabolic bone disease characterized by extensive bone resorption and replacement by fibrous connective tissue and poorly mineralized immature bone.
- the result of persistent elevations of plasma PTH levels **(hyperparathyroidism**).
- Primary( rare, but can see in dogs with tumors) or secondary( more common- nutritional)
- Secondary (most common) can be:
• Nutritional (low Ca or high P diets) or Renal
65
Toxic Osteodystrophies
**_Lead poisoning:_** Lead interferes with osteoclastic activity. Subtle bone lesions leads to Increase bone density (osteosclerosis) _in the metaphysis leads to “lead line”- near the growth plate_ in a young animal or the episeal plate in a mature animal- LEAD INHIBITS OSTEOCLAST REABSORPTION
**_Fluoride toxicosis:_** Occurs in herbivores mainly cattle and sheep. Affects the normal metabolism of bone and **teeth** primarily in growing animals. **Ameloblasts(produce enamel) and odontoblasts(produce dentin)** are markedly sensitive to excess fluoride and the result are **soft dark-brown discolored teeth that wear down easily** (defective enamel and dentine - odontodystrophy). Bones exhibit periosteal hyperostosis.- fluoride may be present in underground water
**_Hypervitaminosis A:_** The most well know syndrome is observed in **cats** that consume high quantities of **bovine livers** (high vitamin A content) for a long period of time leads to _deforming cervical ankylosing(fixation) spondylosis._ The disease is more common in Australia and Uruguay. Affected cats develop osteophyte formation around the joints of the **cervical vertebrae,** shoulder and elbow. (also known as cervical ankylosing spondylosis or disseminating ankylosing osteoarthropathy).
66
Bone Reaction to Injury
_Necrosis:_ Osteonecrosis or Osteosis. In animals bone ischemia is usually associated with trauma but may also occur in inflammatory and neoplastic bone diseases. Necrotic bone appears paler.
• _Microscopically:_ Cell death with loss of osteocytes from their lacunae.- empty lacunae
67
Outcome of osteonecrosis
- Influenced by the size and extent of necrosis and by the extend and strength of collateral circulation and local repair mechanisms.
- Complete resorption and replacement of necrotic bone may occur
- Formation of a _“sequestrum”_ A piece of necrotic bone isolated from the remaining viable bone.
- Attempts to wall off a sequestrum will result in the formation of a layer of granulation tissue and reactive bone known as an “involucrum”
68
Foal, focal osteomyelitis with sequestrum(toward the bottom of the picture). Cornell Files
in a young animal
sequestrum will result in the formation of a layer of granulation tissue and reactive bone know as an "involucrum"
69
Bone Fractures
_Traumatic:_ Normal bone broken by excessive force
_Pathologic:_ Abnormal bone broken by minimal trauma or normal weight bearing
Complete or Incomplete
Closed (simple) or Open (compound- poor prognosis because of the exposure to the outside world)
_Comminuted-_ fracture that results in mulitple bone fragments
_Avulsed:_ Caused by the pull of a ligament/muscle tendon at its insertion into bone.
_Microfracture/ infraction:_ fracturing of trabeculae without external deformation of cortical bone--- more on the microscopic level
70
Cornell, _Pathologic fracture_, Osteosarcoma, dog
VERY COMMON IN DOGS
71
Fracture Repair
72
Healed humeral fracture, feedlot steer, UCVM, OI
73
Complications associated with bone fractures
- Bone necrosis and formation of a sequestrum
- Nonunion fracture pseudoarthrosis (false joint) formation
- Osteomyelitis (compound fractures)
- Cachexia( wild animals)
74
Pig – vertebral abscess resulted in fracture of the vertebral body and focal compression of the spinal cord, common sequel of **tail biting.** AVC
can cause intendtion of the spinal cord
75
rib fractures are difficult
76
Aseptic inflammation
rauma may cause osteoperiostitis with formation of exostosis (osteophytes).
77
Infection
Local or systemic (hematogenous route)
78
Osteomyelitis
Most common in young farm animals as the result of bacteremia or septicemia
79
Omphalophlebitis
Omphalophlebitis is a common source of osteomyelitis in neonates
80
In piglets Osteomyelitis often localizes in
In piglets the infection often localizes in vertebral bodies
81
Osteomyelitis also tends to localize in
Infection also tends to localize in metaphyses of long bones due to the microanatomy of vessels.
82
Blood vessel from the bone marrow come close to the growth plate and turn very softly
bacteria can colonize easier
83
Physitis has extended to the periosteum and metacarpal phalangeal joint, foal
osteomylitis- change in the color of the bone- have a rim of inflammation/congestion; in the area of the growth plate
84
Embolic osteomyelitis, foal. Note Area of bone necrosis (arrow).
lesions cloase to epiphysisal growth plate
sequestrium- necrosis and inflammation
bacteria that can cause this: E. coli, salmonella(espesically in foals),
85
Bovine Actinomycosis, “lumpy jaw”, UCVM
pyogranolomatous osteomylitis
Etiological agent- actinomyces bovis
engorgment of the mandible
Involvment of the mandbile and maybe maxilla
86
Chronic pyogranulomatous osteomyelitis – Actinomycosis
lesions in the mouth or a bad tooth- can be portal of entry
87
Pyogranulomatous Osteomyelitis, Actinomycosis
sulfur granules- characterisitized by large bacterial colonies surrounded by neutrophils and on outside- macrophages, lymphocytes
88
Splendore Hoeppli- eosinophilic filaments that surround the bacteria- represents the antigens/antibody complexes
89
**Gram positive bacteria**, Actinomyces bovis, UCVM, OI
MOSTLY BONE
90
“Lumpy Jaw” (Actinomycosis) – cow.
Actinomyces bovis. Note osteolysis of the macerated and bleached bone specimen- bone remodeling
91
Chronic pyogranulomatous Osteomyelitis
Nocardia spp. was identified by culture and PCR
92
Hypertrophic pulmonary osteoarthropathy or osteopathy.
BONE DISEASE OF UNCLEAR ETIOLOGY
* Sporadically reported in humans (“Marie’s Disease”) and domestic animals, specially dogs.
* Usually observed in individuals with an intra-thoracic space- occupying mass (tumor, abscess).
**Characterized by painful swelling of limbs** caused by periosteal bone proliferation (hyperostosis) in long bones.
Bone changes can regress if the space-occupying lesion in the thoracic cavity is removed.
93
Hypertrophic pulmonary osteoarthropathy or osteopathy is also occasionally observed.
In young dogs with **rhabdomyosarcomas(skeletal muscle malignant tumors)** of the urinary bladder and mares with ovarian tumors.
bone proliferation along the periosteium
94
Canine craniomandibular osteopathy (“Lion Jaw”)
BONE DISEASE OF UNCLEAR ETIOLOGY
* **Proliferative disorder** confined to the bones of the skull, especially **the mandibles**, **occipital and temporal bones**
* Most Common in West Highland White Terriers were a genetic etiology is suspected.
* Usually recognized at 4-7 months of age
* Affected dogs may exhibit discomfort when chewing or inability to open the mouth to eat.
95
Canine craniomandibular osteopathy (“Lion Jaw”)
West Highland White Terrier
96
Bone Neoplasia
Primary tumors are more common than secondary tumors(metistatic)
Primarily observed in dogs and to a lesser extent cats
Tumors of bone and cartilage cell-lines are the most common
In dogs most tumors of bone are malignant- osteosarcoma and chondrosarcoma
I_n horses, cattle and other domestic animals benign tumors of bone are more common than malignant ones_
97
Primary Bone Neoplasms
Osteoma- benign tumor of bone
Ossifying fibroma- can be seen in young horses- in the cranial portion of the manidle
Osteosarcoma
Chondroma
Chondrosarcoma
Multilobular tumor of bone- tumor in dogs; located in the skull- locally aggressive; grows slowly but because of location - it can supress the brain and cause death
98
Osteoma, maxilla, Sheep-McGavin
**we don't see a lot of primary bone tumors in LA**
99
Osteosarcoma
_Most common primary bone tumor in dogs and cats_
Highest incidence in Large breeds like St. Bernard, Great Dane, Irish Setter, Boxer, Doberman, Rottweiler and Labrador Retrievers
Mean age of affected dogs is 7.5 years but dogs less than 2 years old can be affected
Most common in male dogs
100
In the dog osteosarcoma has
a relatively specific site predilection:
In the dog osteosarcoma has
a relatively specific site predilection:
“Close to the knee and away from the elbow”
101
## Footnote
Osteosarcoma, 11 y- Female Rottweiller,
poor prognosis
102
Osteosarcoma, 2 year-old Poodle, Atlantic Veterinary College
stifle joint
103
Chondrosarcoma
Accounts for approximately 10% of primary bone tumors in the dog
Rare in other domestic animals
**In all species it involves flat bones (ribs, nasal turbinates and pelvis) more often than long bones**
104
Chondrosarcoma, skull, dog -McGavin
Example of chondrosarcoma in a long bone- humerus of a mastiff
105
Chondrosarcoma, rib, cat, McGavin
106
Chondrosarcoma, humerus
107
Chondrosarcoma, humerus
108
Articulations or joints are formed when
Articulations or joints are formed when two or more bones are united by fibrous, elastic or cartilaginous tissues or by a combination of these tissues
109
Types of Joints
1. _Fibrous joints (synarthroses):_ Bones are united by fibrous tissue. a. E.g., sutures: cranial bones
b. syndesmosis: tibial-fibular joint
c. gomphoses: Teeth and alveolar bone
2. _Cartilaginous joints (Amphiarthroses):_ Bones are united by hyaline cartilage (e.g., costochondral joints) or fibrocartilage (pelvic and mandibular symphyses, intervertebral joints).
3. **_Synovial Joints (True joints or Diarthroses):_** Unite two bone ends covered by hyaline articular cartilage and an articular capsule surrounds a cavity filled with synovial fluid.
110
Joint reaction to injury
Most common joint lesions in domestic animals involve synovial (diarthrodial) joints
• Injury to articular cartilage results in erosion/fibrillation(fraying- loss of cartilage and extracellular matrix), eburnation( all of the articular cartilage is gone!- exposure of the subchronal bone and has a shiny apperance) or “Joint mice” formation
111
On left- normal
on right- abnormal
left center- erosion of the bone
right/right center- complete loss of articular cartilage
112
**Osteophyte formation(lumps)** may be a sequel of chronic joint injury- this will help with formation of new bone(bone spurs)
articular cartilage looks granular, it's discolored. There is erosion here
113
**Villous hypertrophy/ hyperplasia** of the synovial membrane is other manifestation of chronic joint injury
femoral head- loss of articular cartilage; exposure of subchondral bone- characterized by erosion of bone
114
Pannus formation
another possible sequel to chronic joint injury
115
Pannus
Pannus is a fibrovascular (granulation) and histiocytic tissue that develops within the synovial membrane at its junction with the periosteum and cartilage margins (transitional zone) and can spread over the articular surfaces as a velvety membrane.
Inflammatory cells within the pannus along with collagenases from synovial fibroblasts may further damage the articular cartilage and lead to ankylosis (fixation) of the joint.
116
Pannus formation
117
End-stage Joint
Generic term to describe a joint with severe chronic injury.
Affected joints exhibit variable degrees of damage to the articular cartilage, deformation, osteophyte and pannus formation, capsular fibrosis, synovial villous hypertrophy/ hyperplasia and occasional ankylosis (fixation, immobility).
118
Osteochondrosis (Dyschondroplasia)
_Developmental Joint Diseases:_
**MOST COMMON CAUSE OF LAMENESS IN YOUNG ANIMALS**
Characterized by abnormal growth and maturation of the articular cartilage
Severe degenerative joint disease is a common sequel
**It is the most common cause of lameness in domestic animals, especially _swine, horses_, poultry and large breed dogs**
Pathogenesis is multifactorial but poorly understood
Whatever the underlying causes **ischemic damage** to the growing cartilage seems to play a significant role
In rapidly growing pigs the incidence may reach close to 100%
119
Osteochondritis Dissecans (OCD)
Osteochondritis Dissecans (OCD) specific form of osteochondrosis
Specific form of osteochondrosis characterized by the separation of a piece (flap) of articular cartilage from the subchondral bone.
_In dogs lesions are more common in young fast-growing males of large and giant breeds and affect primarily the shoulder and elbow joints._ Lesions in the elbow joint form part of the “elbow dysplasia syndrome” which also includes ununited anconeal process and fragmented (or ununited) medial coronoid process of the ulna; important orthopedic conditions in young dogs.
120
OCD is an important disease in
OCD is an important disease of horses and a common cause of lameness in young animals.
121
In horses OCD lesions can be\_\_\_
common affected sites?
In horses OCD lesions can be widespread but the stifle, hock and fetlock joints are commonly affected sites.
122
OCD lesions in dogs. SHOULDER COMMONLY AFFECTEDHumeral head
123
OCD lesions in dogs. Humeral head
deformaty in the bone
124
Stifle joint in a horse
areas of ulceration
125
humerus of a pig OCD or osteochondritis dissencants
126
127
OCD lesion, distal femur, lateral ridge, horse
erosion and ulceration with exposure of the underlying subchondrol bone
128
OCD lesion, distal femur, lateral ridge, horse, UCVM – 2009
Note abnormal growth of the articular cartilage and subchondral bone resulting in deformation of the trocheal groove and ridges, OI.
129
Osteochondrosis, Pig, femoral head
130
**normal** femoral head, pig
131
Osteochondrosis dissenticans, pigs, UCVM, OI
132
Hip Dysplasia
Very important orthopedic disease in **large breed dogs**(German Shepards espesically) – occasionally seen in other species
**Characterized by a lack of conformity between the femoral head and the acetabulum leads to subluxation which leads to DJD.**
Polygenic mode of inheritance has been postulated in dogs but environmental factors as nutrition and rapid growth plays a significant role
Joint laxity (instability) is an early finding
133
Femur (femoral head) –Dog with hip Dysplasia
134
subchondral bone is gone
135
DJD –Hip Joint, Aged German Shepherd
erosion of the articular cartilage
136
Intervertebral Disk Disease
Occurs in all dog breeds as part of the aging process
There are differences between IDD in chondrodystrophic(Dashunds etc, these are pre-diposed) and non- chondrodystrophic breeds regarding the age of onset and the nature of the degenerative changes
IDD is one of the most common causes of paresis in the dog
137
Hansen’s type I (B) - DASHSUNDS- Disk Extrusion
type II (A)- MORE COMMON IN NON- CHRONDODYSTROPIC DISEASES- Protrusion- associated with aging
138
IDD - Dog-
Hanesne's Type II- as seen in older dogs
139
Spondylosis (spondylosis deformans, ankylosing spondylosis (itis)
“ Common degenerative disease of the vertebral column **characterized by the formation of osteophytes(bone spurs)** at the ventral and lateral margins of vertebral bodies adjacent to vertebral spaces” –JKP- G Maxie, Ed-2007
_The initial lesion appears to be degenerative changes in the ventral annulus fibrosus-_ this results in fixation of the joints
140
Spondylosis is most common
Spondylosis is most common in **old bulls**, pigs (sows and boars) and dogs
assoicated with increased age
141
Spondylosis
_Lesions are seen in almost every bull past the middle age and is especially common in those used for artificial insemination._
Usually an incidental finding but may cause mild to severe clinical signs (posterior weakness, ataxia or even paralysis).
142
Spondylosis deformans, 20 year-old donkey, TAMU
143
Ankylosing spondylosis – aged bull, Cornell Show and Tell, Dr. King Macerated and bleached bone specimen.
Osteophytes (“bone spurs”).
144
31 year-old gelding In thin body condition
(395 kg). Loosing weight.
In addition to swayback this horse had severe degenerative joint disease. Poor tail tone and mild proprioceptive deficits in the hind limbs were noticed on examination
Lumbar segment of vertebral colon, _Intervertebral disk disease (IDD)_ Leading to sub-luxation of L3-L4; formation of oseteophytes
spondylosis
Close up of the lesions in the medial condyle of the right humerus
lordosis(ventral deviation of the spinal column)
145
Degenerative Joint Disease –Synovial Joints (osteoarthritis/ osteoarthrosis)
_Primary DJD:_ No apparent predisposing cause. **Generally observed in older animals** (age-related DJD).
_Secondary DJD:_ Associated with an **underlying abnormality** in the joint or its supporting structures which leads to premature degeneration of the articular cartilage (e.g.: hip dysplasia in dogs, trauma, inflammation)- atheletes
146
Ringbone:
Degenerative disease in horses affecting the inter-phalangeal joints **(Secondary DJD**)
chronic trauma to the joints
common in horses used in rodeo or polo events
147
Common in horses used in rodeo events or Polo chronic trauma. The result of abrupt stops, turns and twists
Ring bone
148
Inflammatory Joint Disease
Osteomylitis
Route of Infection:
**Most common in farm animals,** specially the young where its a common sequel to neonatal bacteremia Non-infectious arthritis occur most often in dogs and
cats and have an immune- mediated etiology.
149
Common bacteria isolated from septic arthritis
Trueperella (Arcanobacterium) pyogenes – cattle and swine
Erysipelothrix rhusiopathiae – swine, sheep, birds
E. coli – calves, piglets
Streptococcus suis – pigs 2-10 weeks old
Haemophilus suis and parasuis - 5-12 weeks old pigs
Mycoplasma hyorrhinis –pigs 3-1o w
Mycoplasma hyosynoviae – pigs more than 10 weeks old
Histophilus somni - cattle
Mycoplasma bovis - cattle
Borrelia burgdorferi (Lyme disease), humans and dogs
150
Viral arthritis
_Caprine Arthritis-Encephalitis (CAE):_ is a slowly progressive disease of goats caused by a retrovirus. The virus also produces a respiratory and neurologic syndrome. **Joint lesions are characterized by a lymphocytic hyperplastic synovitis with the formation of carpa_l hygromas._**
The hygromas are chronic lesions that appear as flattened cystic fluid-filled subcutaneous distensions over the cranial carpus. Usually there is no communication with the carpal joint or tendon sheath.
A high prevalence of hygromas and lameness in a goat herd is a characteristic feature of CAE.
151
Non-infectious arthritis
Occur most often in dogs and cats and affect multiple joints (polyarthritis)
Have an immune-mediated etiology (rheumatoid-like arthritis)
The inflammation is in response to persistence of antigen in the synovial membrane of affected joints, likely the sequel of previous infection, or to the deposition in the synovium of immune complexes derived from inflammatory lesions elsewhere.
Erosive and non-erosive forms are described
**NOT AS COMMON**
152
Malignant Neoplasms of Joints
* Arise from the synovial membrane
* Uncommon in dogs and very rare in other species
* Two types: BOTH RARE
* _Synovial cell sarcoma:_ malignant tumors arising from synovial fibrocyte
origin
• _Histiocytic sarcoma:_ malignant tumors arising from cells of histiocytic phenotype, possible dendritic (Langerhans) cells present in the synovium.
