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105 Cards in this Set

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woven bone
immature bone, present during fetal development or early stages of repair; collagen fibers are randomly distributed and have crisscross pattern
lamellar bone
mature bone present in normal adult stages; collagen fibers are perfectly arranged in parallel pattern
compact/cortical bone
dense walls of diaphysis; high density; concentric layers of bone tissue with channel in the center for blood vessels, lymphatic vessels, and nerves longitudinally traverse the bone (haversian system)
cancellous/trabecular
spongy bone of medullary cavity; 3-d lattice of interlacing spicules or trabeculae; spaces between spicules is bone marrow
osteoblasts
produce osteoid (bone matrix); activity is dependent on stimuli such as PTH, vitamins C and D; eventually become surrounded by mineralized bone matrix and become osteocytes
osteocytes
reside in bone lacunae and are actively involved in mineral resorption (osteocytic osteolysis) under stimulation of PTH, vitamin D, calcitonin, etc
osteoclasts
multinucleated from same cells that give rise to monocytes and macrophages; actively involved in resorption/lysis of bone (osteocytic osteolysis); found along osseous surface undergoing resorption, where they produce concavities called Howship's lacunae; stimuli include PTH, vitamin D, calcitonin (neg feedback), PG2a, osteoblast-derived factor, etc
3 pools of calcium - how is movement controlled between these?
1. bone calcium - 99% of body's Ca
2. intracellular
3. extracellular (smallest amt)
Movement controlled in intestine, bones, kidneys, hormones (PTH, calcitonin, vitamin D)
Calcium:Phosphorus ratio - effect of changing this
If low (hypocalcemia) or if ratio is simply changed, Ca is transferred from bones to extracellular pool
osteopenia
loss of skeletal mass or "too little bone." remaining bone may or may not have normal composition
intramembranous/appositional ossification
primarily in flat bones and along periosteal surfaces of long bones; proliferation of mesenchymal CT forming a flat membrane which is replaced by mature bone
endochondral ossification
longitudinal growth of long bone, and other bones with growth plates; growth cartilage is replaced by bone; good vascular supply is necessary; occurs in ossification centers of immature bone and growth plates/epiphyseal plates of developing bone
chondrodysplasia
generalized malformation; defective endochondral ossification that results in short-legged dwarfism. common in cattle and dogs. membranous/appositional ossification is normal but endochondral ossification is impaired; lethal/non-lethal forms. Domed head, prominent eyes, and anemia also common.
dyschondroplasia
acquired lesion in which cartilage necroses; not synonymous with chondrodysplasia
osteopetrosis
inherited, generalized malformation. defective osteoclasts fail to reabsorb and remodel the fetal bone (primary spongiosa). increased bone density results with concurrent reduction of medullary spaces. aplastic anemia often follows. dogs/pigs/sheep/horses/cattle/humans. on cut surface, appear diffusely solid but have greater likelihood of fracture.
congenital cortical hyperostosis of pigs
affects long bones; exaggerated periosteal/appositional growth; limbs appar swollen because of excessive trabecula on periosteal surface and edematous blockage of lymphatics. most piglets are born dead or die within hours. joints are normal.
exostosis, endostosis, hyperostosis
ex: new bone grows on outside of bone - small portion
end: new bone grows inside
hyper: new bone grows on entire length of bone (not including joints)
amelia, hemimelia, phocomelia, peromelia
a - absence of limbs
hemi - absense of distal half of limbs
phoco - absence of proximal portion portions
pero - absence of distal portions of limbs
micromelia, syndactylia, polydactylia
micro - small limbs
syn - fusion of digits
poly - supernumerary digits
lordosis, kyphosis, scoliosis, kyphoscoliosis
lord - ventral deviation of spine
kyp - dorsal deviation
scoliosis - lateral deviation
kyposcolio - dorsolateral deviation
angular limb deformity
common in horses; lateral deviation of distal portion of one or more limbs. may be present at birth or develop later in life. causes: malposition in utero, joint laxity, hypoparathyroidism (congenital goiter), trauma (ischemia/reduced blood supply), malnutrition, defective endochondral ossification
osteoporosis
bone atrophy; negative balance between bone formation and resorption leading to reduction in bone mass; bone that is present is normal; reduction in thickness of cortical bone and reduced number of trabeculae of cancellous bone; medullary cavity appears enlarged with increased fragility/fractures (but not soft)
causes of osteoporosis (8)
starvation, parasitism, chronic wasting disease, deficiencies of copper/calcium, hyperadrenocorticism, prolongud use of steroids, physical inactivity, senility
rickets
softening of bone in young/growing animals; deficient calcification of osteoid and cartilagenous matrixes (endochondral ossification); areas of end. oss. appear swollen in humans (costochondral joints) and growth plants are abnormally wide - chondrocytes proliferate during growth but never mature and degenerate so cartilage is retained and accumulates in bone.
causes of rickets
insufficient vitamin D or phosphorus; common in animal houses with poor sunlight
osteomalacia
softening of bones in grown animals; same as rickets; growth plates have already closed; unmineralized osteoid is resistant to osteoclasts so it accumulates in bones - they become soft and deformed; fractures are common
osteodystrophia fibrosa/fibrous osteodystrophy/bran disease
metabolic disease; increased osteoclastic resorption of bone and replacement with CT; results from prolonged PTH secretion (from primary or secondary hyper-parathyroidism); cranio-facial bones are more commonly affected; teeth may become loose and soft
causes of osteodystrophia fibrosa
may be due to diets rich in phosphorus and low in calcium; in dogs may be due to chronic renal disease
renal osteodystrophy
inability of kidneys to excrete P; high plasma P and low Ca stimulate PTH which removes Ca from bone and increases Ca absorption in the GI; animals are also unable to activate vitamin D3 in kidneys
primary hyperparathyroidism
active parathyroid adenomas - rare in domestic animals
secondary hyperparathyroidism
nutritional or renal; reduced concentration of calcium in plasma with relative increase in Phosphorus; excessive secretion of PTH promotes osteoclastic activity; bones become soft (especially of head) and prone to fractures; impt in horses (bran dz), dogs (rubber jaw), cats (renal osteodystrophy), captive primates and reptiles, sporadic in farm animals
nutritional - low-Ca/high P diet
renal - failure to eliminate P in urine (hyperphosphatemia results)
lead poisoning
interferes with osteoclastic activity; lesions subtle - increased bone density in metaphysis (osteoclasts have typical acid-fast inclusions)
osteofluorosis
from chronic ingestion of fluorides in water, plants, rocks, etc in some regions. affects only herbivores; flurosis interferes with normal metabolism of bones and teeth, especially in fetusus and growing animals - bones become thickened due to excessive periosteal ossification; produces rickets-like lesions and softenening of teeth (odontofluorosis - soft, black teeth with excessive wear and tear of occlusal surfaces) concentration must reach 2500ppm in bones to cause a problem.
hypervitaminosis A
toxic osteodystrophy in cats (somewhat in calves and piglets); cats fed livers of grazing cows or any feed with excessive vit A; periosteal surfaces become rough causing deforming cervical spondylosis; vertebrae have abundant exostosis and can fuse causing vertebral ankylosis; vitamin A may stimulate osteoblastic activity
bone necrosis - gross/histo findings
gross: softening, discoloration
micro: empty lacunae, resorption
possible sequelae to bone injury (4)
1.necrosis --> resorption --> woven bone --> mature bone
2.necrosis --> resorption --> woven bone --> scar
3.necrosis --> sequestrum (no resorption)
4. necrosis --> resorption --> inflammation --> proliferation (exostosis)
sequestrum
involucrum
bone proliferation
sequestrum - piece of necrotic bone isolated from remaining viable bone
involucrum - dense collar of bone surrounding a sequestrum
bone proliferation - exostosis, enostosis, hyperostosis (chronic periosteal injury leads to bone proliferation)
aseptic bone necrosis
rare in domestics - aseptic necrosis of femoral head is important in dogs; results from bone ischemia; empty lacunae with little inflammation
pathway of bone reaction to fracture
fracture > hematomas > necrosis > resorption > periosteal/mesenchymal proliferation > cartilage > woven bone > lamellar bone > callus
osteitis
osteomyelitis
periosteitis
panosteitis
osteitis - inflamm of bone
osteomyelitis - inflamm of bone due to pyogenic infection
periosteitis - inflamm of periosteum
panosteitis - inflamm of all parts of bone
lumpy jaw
bacterial osteomyelitis caused by Actinomyces bovis; penetrates thru injured oral mucosa and causes chronic pyogranulomatous osteomyelitis; mandible becomes swollen, deformed, produces a fistula with purulent exudate containing sulfer granules; macerated jaw shows exostosis; microscopically - confluent pyogranulomas with aggregates of bacteria called club colonies. test/slaughter infected animals.
hematogenous osteomyelitis
common in farm animals following bacteremia/septicemia (frequently: salmonella, A. pyogenes, S. aureus, etc); omphalophlebitis (infection of umbilical cord) is common source of bacterial embolisms in neonates - these lodge primarily in epiphysial vessels of long bones (70% of foals with joint ill have septic osteomyelitis)
also common in vertebrae (spondylitis) in pigs from tail biting - can cause spinal meningitis or weaken the bone causing fractures. ventral bodies of vertebrae appear swollen and have mucopurulent exudates on cut surfaces (spinal abcesses).
mycotic osteomyelitis
caused by Blastomyces dermatitides, Coccidoides immitis, and Cryptococcus neoformans; these disseminate thru the blood and lymph to many tissues, including bones. causes a chronic granulomatous osteomyelitis with exostosis.
viral osteitis - common causes?
uncommon in domestics; canine hepatitis-1, canine morbillivirus (distemper), feline leukemia virus, bovine virus diarrhea (lesions in other organs more important)
bone dz of unknown etiology
hypertrophic/pulmonary osteoarthropathy (marie's dz in humans); unclear pathogenesis but accompanied by intrathoracic space-occupying mass (tumor or abscess); change of blood flow in extremities may be underlying mechanism of periosteal exostosis, or pulmonary anastomoses (arterioles/venules) allow circulating megakaryocytes to bypass lung and reach periosteal surface to induce growth. tumors of urinary bladder and ovaries also associated with hypertrophic pulmonary osteoarthropathy.bone changes are always bilaterally symetrical with multiple focal to coalescing osteophytes that affect appendicular skeleton.
craniomandibular osteopathy/lion jaw
localized bone dz, unknown etiology in dogs (west highland terriers and scottish terriers); lesions affect only the head, bilaterally symmetrical, self-limiting; swelling of temporo-maxillary region; proliferative changes in bones causing bony bridging on periosteal surface
fribrous joints (synarthrosis)
cartilagenous (amphiarthrosis)
synovial (diarthrosis)
fibrous - joints united by fibrous tissue; 3 types: sutures, syndesmosis/tibia-fibula, and gomphosis/tooth
cartilagenous - joints united by hyaline cartilage (costochondral) or fibrocartilage (pelvic, mandibular symphysis)
synovial - 2 bone ends united by articular cartilage and surrounded by a capsule; appendicular skeleton and vertebral joints (most impt bone dz affect synovial joints)
PM exam of synovial joints
articular cartilage should be smooth and moist, glistening with a bluish color; it is formed by type II collagen and proteoglycans, lacks blood vessels, poor capacity for regeneration; necrosis of cartilage (chondromalacia) remains unrepaired
synovial fossae
bilateral depressions not covered by cartilage; function is unknown but may be for lubrication; appear in first few months of life and may be mistaken for an articular lesion
synovial fluid
clear, viscous, colorless to slightly yellow produced by synoviocytes; low cellularity and low protein content; functions to reduce friction and nourish articular cartilagenous; increases during most synovial diseases - synovial effusion; fluid becomes turbid in inflammatory joint dz because of increase in protein content and leukocytes
articular capsule
thick sack of connective tissue covering entire joint and providing stability; thin synovial membrane lies internally to line the capsule; may become thickened due to fibrosis and deposition of exudate
synovial membrane and synoviocytes
thin membrane with discrete villi lined by specialized cells called synoviocytes; 2 types of synoviocytes - A phagocytic activity, B produce fluid
viral osteitis - common causes?
uncommon in domestics; canine hepatitis-1, canine morbillivirus (distemper), feline leukemia virus, bovine virus diarrhea (lesions in other organs more important)
bone dz of unknown etiology
hypertrophic/pulmonary osteoarthropathy (marie's dz in humans); unclear pathogenesis but accompanied by intrathoracic space-occupying mass (tumor or abscess); change of blood flow in extremities may be underlying mechanism of periosteal exostosis, or pulmonary anastomoses (arterioles/venules) allow circulating megakaryocytes to bypass lung and reach periosteal surface to induce growth. tumors of urinary bladder and ovaries also associated with hypertrophic pulmonary osteoarthropathy.bone changes are always bilaterally symetrical with multiple focal to coalescing osteophytes that affect appendicular skeleton.
craniomandibular osteopathy/lion jaw
localized bone dz, unknown etiology in dogs (west highland terriers and scottish terriers); lesions affect only the head, bilaterally symmetrical, self-limiting; swelling of temporo-maxillary region; proliferative changes in bones causing bony bridging on periosteal surface
fribrous joints (synarthrosis)
cartilagenous (amphiarthrosis)
synovial (diarthrosis)
fibrous - joints united by fibrous tissue; 3 types: sutures, syndesmosis/tibia-fibula, and gomphosis/tooth
cartilagenous - joints united by hyaline cartilage (costochondral) or fibrocartilage (pelvic, mandibular symphysis)
synovial - 2 bone ends united by articular cartilage and surrounded by a capsule; appendicular skeleton and vertebral joints (most impt bone dz affect synovial joints)
PM exam of synovial joints
articular cartilage should be smooth and moist, glistening with a bluish color; it is formed by type II collagen and proteoglycans, lacks blood vessels, poor capacity for regeneration; necrosis of cartilage (chondromalacia) remains unrepaired
synovial fossae
bilateral depressions not covered by cartilage; function is unknown but may be for lubrication; appear in first few months of life and may be mistaken for an articular lesion
synovial fluid
clear, viscous, colorless to slightly yellow produced by synoviocytes; low cellularity and low protein content; functions to reduce friction and nourish articular cartilagenous; increases during most synovial diseases - synovial effusion; fluid becomes turbid in inflammatory joint dz because of increase in protein content and leukocytes
articular capsule
thick sack of connective tissue covering entire joint and providing stability; thin synovial membrane lies internally to line the capsule; may become thickened due to fibrosis and deposition of exudate
synovial membrane and synoviocytes
thin membrane with discrete villi lined by specialized cells called synoviocytes; 2 types of synoviocytes - A phagocytic activity, B produce fluid
viral osteitis - common causes?
uncommon in domestics; canine hepatitis-1, canine morbillivirus (distemper), feline leukemia virus, bovine virus diarrhea (lesions in other organs more important)
bone dz of unknown etiology
hypertrophic/pulmonary osteoarthropathy (marie's dz in humans); unclear pathogenesis but accompanied by intrathoracic space-occupying mass (tumor or abscess); change of blood flow in extremities may be underlying mechanism of periosteal exostosis, or pulmonary anastomoses (arterioles/venules) allow circulating megakaryocytes to bypass lung and reach periosteal surface to induce growth. tumors of urinary bladder and ovaries also associated with hypertrophic pulmonary osteoarthropathy.bone changes are always bilaterally symetrical with multiple focal to coalescing osteophytes that affect appendicular skeleton.
craniomandibular osteopathy/lion jaw
localized bone dz, unknown etiology in dogs (west highland terriers and scottish terriers); lesions affect only the head, bilaterally symmetrical, self-limiting; swelling of temporo-maxillary region; proliferative changes in bones causing bony bridging on periosteal surface
fribrous joints (synarthrosis)
cartilagenous (amphiarthrosis)
synovial (diarthrosis)
fibrous - joints united by fibrous tissue; 3 types: sutures, syndesmosis/tibia-fibula, and gomphosis/tooth
cartilagenous - joints united by hyaline cartilage (costochondral) or fibrocartilage (pelvic, mandibular symphysis)
synovial - 2 bone ends united by articular cartilage and surrounded by a capsule; appendicular skeleton and vertebral joints (most impt bone dz affect synovial joints)
PM exam of synovial joints
articular cartilage should be smooth and moist, glistening with a bluish color; it is formed by type II collagen and proteoglycans, lacks blood vessels, poor capacity for regeneration; necrosis of cartilage (chondromalacia) remains unrepaired
synovial fossae
bilateral depressions not covered by cartilage; function is unknown but may be for lubrication; appear in first few months of life and may be mistaken for an articular lesion
synovial fluid
clear, viscous, colorless to slightly yellow produced by synoviocytes; low cellularity and low protein content; functions to reduce friction and nourish articular cartilagenous; increases during most synovial diseases - synovial effusion; fluid becomes turbid in inflammatory joint dz because of increase in protein content and leukocytes
articular capsule
thick sack of connective tissue covering entire joint and providing stability; thin synovial membrane lies internally to line the capsule; may become thickened due to fibrosis and deposition of exudate
synovial membrane and synoviocytes
thin membrane with discrete villi lined by specialized cells called synoviocytes; 2 types of synoviocytes - A phagocytic activity, B produce fluid
cervical vertebral stenotic myelopathy
aka cervicospinal arthropathy/equine sensory ataxia/wobbler syndrome; compression of the spinal cord causing ataxia.primary degenerative change affecting vertebral joints that eventually causes narrowing of the vertebral canal and myelomalacia; clinical signs - incoordination and locomotion disturbances
cervical vertebral instability
pathologic syndrome of stenotic myelopathy in foals (8-15mo); during ventroflexion, instability of C3-C5 causes narrowing of vertebral canal and compression of spinal cord; articular facets of vertebrae may show fibrillation, eburnation, osteophyte formation; may be due to rapid growth, nutrition/genetics, etc
cervical static stenosis
pathologic syndrome of stenotic myelopathy in older horses (1-4yr); hypertrophy of ligamentum flavum causes dorsal narrowing of vertebral canal at C5-C7; static type of compression - doesn't require ventroflexion; may be from hereditary, nutritional, environmental, malformation, articular subluxation
cervical spondylomyelopathies
aka wobbler syndrome in dogs/cervical spondylopathy/cervical vertebral instability/caudal cervical vertebral malformation; similar pathogenesis to those affecting horses; abnormalities in C6-C7 cause chronic compression, myomalacia, and gait deficits; common in dobermans, great danes, other large breeds; abnormalities in spinal cord are typical but those in vertebrae may be hard to evaluate during PM exam
intervertebral disk disease - dorsal protrusion (prolapse)
chondrodystrophoid dogs; annulus fibrosus degenerates and allows dorsal protrusion of nucleus pulposus into spinal canal causing compressive myelomalacia; degenerated disk material mineralizes; onset usually 3-6yr; thoracolumbar and to lesser extent cervical regions; disk material is present in spinal canal and localized
intervertebral disk dz - disk explosion
disk suddenly disintegrates and herniates into spinal canal due to severe compressive trauma to spinal column such as HBC
intervertebral disk dz - embolism of nucleus pulposus
embolus in spinal cord; no gross lesions but microscopic examination of spinal cord reveals fibrocartilagenous material in spinal arteries or veins; this necrotizing myelopathy occurs in dogs, horses, cats, pigs, humans
ankylosing spondylosis
aka spondylosis deformans/ankylosing spondylitis; old bulls/sows/dogs; degeneration of intervertebral disks, periosteal stimulation, osteophytes (on ventral and lateral vertebral bodies), bridging between vertebrae, and ankylosis. abnormal mobility of intervertebral joints is primary cause.
hip dysplasia/acetabular dysplasia
dogs-large and giant breeds, humans; genetic and environmental (nutrition, rapid growth) causes; normal at birth, changes detectable on x-ray at 7 weeks; starts with edema/hemorrhage in the teres ligament followed by coxofemoral subluxation; joint shows fibrillation, eburnation, microfractures of acetabulum, thickening of capsule, formation of osteophytes; articular surface becomes flat in severe cases; dysplasia may be due to reduced pelvic muscle mass, causing instability and abnormal mvmt of the joint; may also be due to intrinsic defect leading to secondary degenerative joint dz
arthropathies
osteoarthritis, osteoarthrosis. nonspecific group of degenerative joint dz affecting appendicular skeleton
osteochondrosis/dyschondroplasia
heterogenous group of degenerative joint dz initiated by abnormal growth or maturation of cartilage (cartilage dysplasia); affects cartilage of metaphyseal growth plate and articular epiphyseal cartilage complex of growing bone; retention of cartilage due to excessive accumulation of hypertrophied chondrocytes; proliferation of cartilage probably exceeds proliferation of vessels required to mineralize the cartilage; dogs/pigs/horses/poultry most affected; secondary changes in the joints are noticeable - eburnation, cartilage collapse, end-stage joint; geetic, biomechanic, and toxicoses may be causes - farms with rapidly growing pigs have 100% rate; many joints are affected in the same animal; in severe cases entire articular cartilage collapses into subchondral bone producing large fissures
osteochondrosis dissecans (OCD)
specific form of osteochondrosis; separation of piece of articular cartilage from subchondral bone; dissected flap of cartilage becomes a joint mouse; most common in med-sized dogs in males; usually shoulders and elbows; in horses distal tibia is most commonly affected but shoulders and hips also affected
infectious arthritis
septic joint inflammation (fibrinous or suppurative) most commonly seen in farm animals; rare in dogs/cats; pathogens: bacteria, mycoplasma, chlamydia, viruses; usually involves many joints; may also involve serosal surfaces (meninges, periotenum, pleura, pericardium, endocardium, heart valves, aqueous humor, vitreous body of eye, omphalitis (in newborns)
ports of entry of infectious arthritis
hematogenous (bacteria, septicemia); spread from contagious infections (osteomyelitis, ulcerative dermatitis)
arcanobacterium arthritis
purulent in cattle/swine
erysipelothrix rhusiopathiae arthritis
swine/sheep/birds, acute septicemic, results in death due to vasculitis and thrombosis, survivors may develop chronic form with arthritis and endocarditis
E. coli arthritis
coliform - newborn calves surviving E. coli septicemia/bacteremia. port of entry - umbilicus, pharynx, intestine
streptococus suis arthritis
pigs 2-10 weeks old; septicemia with acute death or bacteremia with subsequent meningitis and polyarthritis
hemophilus suis or parasuis arthritis
glasser's dz; occurs after stress in pigs 5-12 weeks old; polyarthritis, polyserositis
mycoplasma hyorrhinis or hyosynoviae arthritis
pigs 3-10wks (hyorrhinis) or 10+wks (hysynoviae); slow progressive polyarthritis (serositis only in hyorrhinis)
hemophilus somnus arthritis
cattle; septicemia/abortion/pneumonia; seein in animals dying of Thromboembolic Meningoencephalitis (TEME)
mycoplasma bovis arthritis
cattle - pneumonia, septicemia, arthritis
borrelia burgforferi arthritis
spirochetal infection transmitted by ticks to dogs/humans
caprine arthritis-encephalitis (CAE)
viral arthritis; slow, progressive arthritis caused by a retrovirus; joint lesions have lymphocytic hyperplasia synovitis with carpal hyogromas (cysts containing sero-sanguinolent or gelatinous fluid) found over anterior carpus
bursitis, examples
inflammation of synovial bursae; bursae are located around tendons vulnerable to friction-injury; undergo inflammation in response to injury or hematogenous infections
examples: fistulous withers (T2), poll evil (atlanto-occipital) - bursae develop pyogranulomatous inflammation and exudate escapes to skin (fistula); caused by Onchocerca cervicalis and Actinomyces bovis, and Brucella abortus, and trauma;
example: carpal bursitis referred to as carpal hyogromas in ruminants with Brucellosis and goats with CAE
erosive arthritis
non-infectious, immune-mediated; rheumatoid-like arthritis is rare but occurs in dogs; lameness, swelling of joints, anorexia, fever; affects small/toy breeds; lesions are bilateral and only affect appendicular skeleton; IgG/IgM immune complexes, complement, and lysosomal enzymes are to blame; chronic proliferative lympho-plamacytic synovitis with pannus formation and fibrosis; must distinguish from lupus erythematosus
non-erosive arthritis
non-infectious; seen in dogs and cats; caused by depostion of immune complexes in synovial membrane associated with chronic diseases involving kidney, heart, chronic metritis, etc
laminitis
metabolic arthritis; inflammation of the hoof laminae; affects horses and cattle; acute or chronic; may be due to nutritional, histamine, endotoxin, traumatic; reduced vascular perfusion in lamina (P3), with congestion, edema, and separation of the laminae (acute cases), hyperplasia of laminae, rotation of P3, penetration of sole by P3, osteomyelitis in chronic cases
gout
metabolic arthritis cause; depostion of urates in membranes; common in poultry, reptiles, humans (lack of uricase);
articular gout - chronic condition of "normal" animals fed large amts of protein or in chickens with genetic impairment in kidney to secrete uric acid resulting in depositioin of uric acid in synovial capsules;
visceral gout - primary kidney failure resulting in deposition of uric acid in kidney, heart, other viscera
osteoma
horse/cattle; smooth, solitary, monstotic nodules formed by intramembranous ossification (cancellous > compact) found in the skull
osteochondromas multiple cartilagenous exostoses
cartilage-capped bony protuberances that stop growing when rest of skeleton does; may either be multiple polyostotic tumors or dysplasia affecting growth of cartilage; common in dogs/horses; appear grossly as multiple bony nodules near growth plates
chondroma
benign tumor arising from cartilage; common in dogs/cats/sheep affecting bones and ribs
osteosarcoma/osteogenic sarcoma
mot common skeletal neoplasm of dogs and cats (80% of all tumors); most common in large breeds around 7.5years; tumors arise from osteoid-producing cells but some cells may differentiate into cartilage or CT (osteoblastic, fibroblastic, chondroblastic, or mixed type); usually involve long bones; tumors can be osteolytic or osteosclerotic; frequently metastasize to other organs (lung esp)
chondrosarcomas
rare tumors arising from malignant chondrocytes; tumoral cells produce cartilagenous matrix but never produce osteoid; frequently seen in dogs/sheep, pelvis, nasal cavity, sternum, ribs are common sites
synovioma/synovial sarcoma
rare tumors arising from synovial cells