Pathology of Bone Pt 2

Question 1

What is the issues that you can see with lead toxicity? What are some causes of lead toxicity in cattle? Can you diagnose via radiograph? What is seem>

Answer 1

• Lead tox-> interferes with osteoclast
◦ Bone lesions can be subtle, increased density (focal area of osteosclerosis in the meaphysis) -> Lead line
◦ Lead causes neurological problems as well
‣ Cows will lick lead ( in gas from tractors ect) and it causes neuronal necrosis/ encephalopathies
◦ Radiologists can make diagnosis via radiographs sometimes.

Question 2

What is seen in this image indicated by the white arrows? What is its cause?

Answer 2

This is a lead line due to increased bone density (osteosclerosis) in the metaphysis. This is due to lead toxicity

Question 3

What is Hypervitaminosis A? What can It cause? Where is it seen frequently in the world?

Answer 3

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 -> deforming cervical spondylosis. The disease is more common in Australia and Uruguay.

Question 4

What happens to cats that are affected with hypervitaminosis A? What clinical signs can you see?

Answer 4

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).

Signs: Can cause lameness, neurologic signs, compression of nerves.

Question 5

What cats are most susceptible to hypervitaminosis A?

Answer 5

Cats that eat fresh beef liver, or alot of beef liver. • Happens where farmers kill animals in field and give the fresh liver to cats. Fresh liver has high levels of vitamin A.

Question 6

What is ankylosis?

Answer 6

Fixation of a joint

Question 7

What occurs in hypervitaminosis A, that causes cervical
ankylosing spondylosis?

Answer 7

◦ Degenerative changes in the cervical vertebrae produce osteophytes ( nodules of new bone) on the periosteal surface and it fixes the vertebra with the one ahead of it. It also will affect the foramina this is why you will see lameness

Question 8

What is occuring in this image? What causes it?

Answer 8

Cervical ankylosing spondylosis - Cat
Cause: Hypervitaminosis A

Question 9

What is osteonecrosis or osteosis? What is it a result of? What do you see microscopically? What is seen grossly?

Answer 9

• Necrosis (Osteonecrosis or Osteosis), the result of ischemic injury. Osteonecrosis is often the result of trauma but may also occur in inflammatory and neoplastic bone disease. Necrotic bone appears paler.

• Microscopically: Cell death with loss of osteocytes from their lacunae.
• any process that could cause impaired vascular supply can cause ischemic necrosis.

Question 10

What are the outcomes of osteonecrosis? What is it influenced by? How can the negative outcome be remedied?

Answer 10

• 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 if there is a good area of blood supply around the bone. Osteo-proginator cells.
• Formation of a “sequestrum” -> A piece of necrotic bone isolated from the remaining viable bone.
Surgical removal of the sequestrum is what needed sometimes to allow for healing. Presence of the sequestrum can cause continued lameness / cause bone to wall off the sequestrum by forming a layer of granulation tissue and an involucrum ( reactive bone)

Question 11

What is the area circled in purple? What is the area circled in green?

Answer 11

Green -> involucrum

Purple -> sequestrum

Question 12

Why is bone inflammation called osteomyelitis? What do you see grossly in these cases? What does a sequestrum look like?

Answer 12

• Whenever you have inflammation of the bone, it is not only the bone so you will also have involvement of the marrow, which is why it called osteomyelitis. The area of bone looks brittle, pale, and as of you can remove a section of it (because you can). Sometimes you can see the body makes grey granulation tissue causing an involucrum

Question 13

What are the kind of bone fractures? What does each mean?

Answer 13

• Traumatic: Normal bone broken by excessive force
• Pathologic: Abnormal bone broken by minimal trauma or normal weight bearing
• Complete or Incomplete ( bone fissure vs. complete fracture)
• Closed (simple) (no open skin, soft tissue is intact) or Open (compound) (open wound, tissue not intact ( more susceptible to secondary infection. )
• Comminuted: Broken into small pieces.
• Avulsed: Caused by the pull of a ligament/muscle tendon at its insertion into bone. ( piece of bone coming out with tendon or ligament due to trauma)
• Microfracture/ infraction: fracturing of trabeculae without external deformation of cortical bone. ( minor very small, osteoporosis can cause micro fracture)

Question 14

What is occuring in this image? What kind of fracture is this?Why? What is the typical cause of this in pigs? What are other causes of this? What are the clinical signs? What is the pathogenesis?

Answer 14

• This is a pathologic fracture
◦ Rickets, osteomalacia, weakened bone, tumor etc.
◦ This happens a lot in pigs, can be fine then pigs were fighting and you find one laying down later and cant get up.
‣ The cause is usually a vertebral abscess resulting in fracture of the vertebral body and focal compression of the spinal cord.
‣ Focal area of suppurative (osteomyelitis vertebral osteomyelacia) , inflammation in the vertebrae. Neutrophils produce cytokines and this will destroy the surrounding tissues . Infection in tail will travel via blood vessels and can cause abscess in the vertebrae.
◦ This can cause focal area of compression of the spinal cord and neurologic signs

Question 15

What is seen in this image? What is the cause? What kind of fracture is seen? What animal is it common in? What are typical clinical signs?

Answer 15

• Osteosarcoma- Relatively common in dogs, can produce alot of damage. These animals can become acutely lame, due to pathologic fracture

Question 16

What is the mechanism/ steps of a complete fracture repair? When are you more able to heal well from a fracture? When is it worse? What is important when intervening surgically for fractures, and what is needed to occure for optimal outcome?

Answer 16

• Bone has great healing capability in children/ younger individuals.
• Harder when older.
• Image far left:
◦ Complete fracture: creates complete hematoma . Hematoma produces meshwork to facilitate the arrival of fibroblasts and neovascularization. Hematoma is important to start healing process. Macrophages and other immune cells will come to clean up necrotic debris as well as secrete cytokines that will result in the activation of osteoproginator cells. These cells will then become osteoblasts and lay woven bone. Some of these cells also produce cartilage and this bone and cartilage will make up the callus in these areas of repair. These areas will eventually become bone. As long as you repair correctly and all bone fragments are opposed correctly + cleanly then you can have complete repair of a fracture. If proper stability is not maintained, less o2 and less neovascularization and less osteo proginator cells. More fibroblasts which will produce connective tissue since fibroblasts are more resistant to hypoxia. Needs to be non mobile to heal perfectly.

Question 17

In a fracture that is not stabilized appropriately, why would you see more fibroblasts than osteoproginator cells?

Answer 17

If proper stability is not maintained, less o2 and less neovascularization and less osteo proginator cells. More fibroblasts which will produce connective tissue since fibroblasts are more resistant to hypoxia. Needs to be non mobile to heal perfectly.

Question 18

What is present in this image? why is it healed the way it is? Will it get better with time?

Answer 18

• healing wasn’t perfect, so since their was not stability of the fracture ( ribs are highly mobile area) their is cartilage / connective tissue in this area.
• you can even see this years later.

Question 19

What is occuring in this image?

Answer 19

Nonunion fracture -> caused
pseudoarthrosis (false joint) formation

Question 20

What are complications associated with bone fractures?

Answer 20

• Bone necrosis and formation of a sequestrum -> osteonecrosis.
• Nonunion fracture -> pseudoarthrosis (false joint) formation (healed primarily with connective tissue, cavity can be formed and even develop synovial fluid)
• Osteomyelitis (compound fractures) ( high possibility with prolonged lack of vet care can happen)
• Cachexia (if you have a fracture, you cant catch food and you can have nutritional deficiency. )

Question 21

What is aseptic inflamation? What can it cause?

Answer 21

• Aseptic inflammation -> trauma may cause osteoperiostitis with formation of exostosis (osteophytes). Osteophytes are nodules of bone usually on the periosteal surface of the bone.
• Infection: Local or systemic (hematogenous route).

Question 22

What is the term for bone inflammation?

Answer 22

Osteitis/ Osteomyelitis

Question 23

What can cause inflammation in the bone?

Answer 23

• Aseptic inflammation -> trauma may cause
osteoperiostitis with formation of exostosis
(osteophytes).

• Infection: Local or systemic (hematogenous route)

Question 24

Who is osteomyelitis most common in? What is it a result of ? What is a common source? Where does the infection usually localize in piglets? Where else are common places to find these lesions?

Answer 24

• Most common in young farm animals as the result of bacteremia or septicemia
• Omphalophlebitis (umbilical infections) is a common source of osteomyelitis in neonates
• In piglets the infection often localizes in vertebral bodies
• Infection also tends to localize in metaphyses of long bones due to the microanatomy of vessels.

Question 25

Where is osteomyelitis usually seen in long bones? Why in this area? What are other things you can see with an infection coming from this area?

Answer 25

• Osteomyelitis in long bones are usually seen right by the growth plate in the metaphysis. This is because the vessel in that area turns sharply, because of this the blood flow slows down and is thinner ( more leaky) so the bacteria can actually exit the blood stream and proliferate in these areas.
• Can even cause fistulous tracts that lead to the skin.
• Can cause suppurative arthritis.

Question 26

What is seen in this image?

Answer 26

• Image on left: severe case of osteomyelitis and necrosis (growth plate almost gone) red ring around growth plate indicates acute inflammation)

Question 27

What can be seen in this image?

Answer 27

Pale areas of necrosis with reddish ring of inflammation around it.

Question 28

What is the usual starting point of osteomyelitis that ends up at the metaphysis of long bones? What are bacteria that can cause this? What is important about investigating the cause via necropsy?

Answer 28

• These lesions usually start by hematological spread and end up in the metaphysis.
• Salmonella (important in foals), Ecoli, Klebsiella, Acinobacterium, can cause these lesions. You always have to culture these to come up with diagnosis.

Question 29

What bacteria is important to remember in regards to foals who have long bone osteomyelitis?

Answer 29

• Salmonella (important in foals)

Question 30

What is the condition seen in this image?

Answer 30

Bovine Actinomycosis, “lumpy jaw”

Question 31

What is the pathogenesis of Bovine Actinomycosis?

Answer 31

• Pathogenesis -> produced by actiomysis bovis which is present in the environment. Animals can have lesions in the oral cavity which can penetrate into the mandible and become this chronic focal suppurative, pyogranulomatous osteomyelitis. They present with a large nodular mandible with presence of fistulous tracks that are draining on the surface with ulceration, and alopecia.

Question 32

What kind of inflamation will you see in the lesions of patients with Bovine Actinomycosis? Where are the lesions typically found?

Answer 32

• Suppurative inflammation of the mandible in cattle.
• Mostly on mandible but can also occur in the maxilla.

Question 33

What is occuring in this image?

Answer 33

Bovine Actinomycosis, (“lumpy jaw”), - involvement of left maxilla

Question 34

What is the cause of this case of Actinomycosis? What changes grossly? What is an morphologic diagnosis for this image?

Answer 34

• Suppurative, pyogranulomatous exudate in this cross section of the maxilla. Effacement of normal nasal cavity/ maxillary sinus. Alot of fibrosis, severe bone damage. You can see their is plant in the gingiva of this animal so the haylage is what caused impaction of the gum, causing osteomyelitis of the maxilla.

Question 35

What is seen in this image?

Answer 35

microscopic view of a sulfur granule

• Sulfur granular are usually yellowish and very small (mm) then you can see the image on the left when you look at sulfur granules microscopically
• Bacteria: staph aureus, actinobacillus (wooden tongue) , actimyces ( actinomycosis)

Question 36

What is seen in this image?

Answer 36

Splendore Hoppli: Immunoglobbulin antibody complex around bacterial complex. You will see a lot of neutrophils/ macrophages surrounding these colonies

Question 37

What is seen in this image? What kind of bacteria is this?

Answer 37

Gram positive bacteria, Actinomyces bovis

Question 38

What is seen in this image? What is the cause?

Answer 38

“Lumpy Jaw” (Actinomycosis) – cow. Actinomyces bovis.osteolysis of the macerated and bleached bone specimen

Areas of bone lysis and bone proliferation in these bones as you can see in the image on the left. This is why the jaw seems enlarged, and has these holes all over the mandible of this cow. This condition also has fistulous tracts that proliferate through bone and can come out at surface of skin and leak suppurative discharge.

Question 39

What is hypertrophic pulmonary osteoarthropathy / osteopathy? Who is it reported in? What are the clinical signs? Can this condition be reversed?

Answer 39

Hypertrophic pulmonary osteoarthropathy or osteopathy.

• Sporadically reported in humans (“Marie’s Disease”) and
domestic animals, especially dogs.sometimes in mares with ovarian tumor

• Usually observed in individuals with an intra-thoracic space-
occupying mass (tumor, abscess).

• Characterized by painful swelling of limbs caused by periosteal
bone proliferation (periostitis, hyperostosis) in long bones.

• Bone changes can regress if the space-occupying lesion in the
thoracic cavity is removed.

Question 40

What can be seen in this image?

Answer 40

Hypertrophic pulmonary osteoarthropathy or osteopathy

Question 41

What can be seen in this image?

Answer 41

Hypertrophic pulmonary osteoarthropathy or osteopathy

periosteal bone proliferation (periostitis, hyperostosis) in long bones.

Question 42

What other causes are there for Hypertrophic pulmonary osteoarthropathy or osteopathy?

Answer 42

The disease is also occasionally observed In young dogs with rhabdomyosarcomas of the urinary bladder and mares with ovarian tumors.

Question 43

What is Canine craniomandibular osteopathy (“Lion Jaw”)? What bones are typically affected?

Answer 43

Proliferative disorder confined to the bones of the skull, especially the mandibles, occipital and temporal bones

Question 44

What breeds are most common for Canine craniomandibular osteopathy (“Lion Jaw”)? What age do usually recognize it? Is it infectious? What are clinical signs?

Answer 44

Most Common in West Highland White Terriers where a genetic etiology is suspected (also reported in several other breeds)

• Usually recognized at 4-7 months of age
• Possible infectious agent suspected but not proven

• Affected dogs may exhibit discomfort when chewing or inability to open their mouth to eat.
◦ Clinical signs when young, enlargement of mandible, pain in mouth, pain eating, ect.

Question 45

What is occuring in this image?

Answer 45

Canine craniomandibular osteopathy (“Lion Jaw”)

Question 46

What condition is this breed predisposed to?

Answer 46

Canine craniomandibular osteopathy (“Lion Jaw”)

Question 47

What kind of tumors of bone are more common? Primary or secondary? Are they seen more in dogs or cats?

Answer 47

• Primary tumors are more common than secondary tumors
• Primarily observed in dogs and to a lesser extend cats
• Frequency of tumors by species: Dogs >Cats> other animals ( large animals mostly benign. )

Question 48

When discussing bone neoplasia, what are the most common cell lines affected?

Answer 48

Tumors of bone and cartilage cell-lines are the most common

Question 49

In dogs are most bone neoplasia benign or malignant? What about in horses, cows, and other domestic animals?

Answer 49

• In dogs most tumors of bone are malignant

• In horses, cattle and other domestic animals benign tumors of
bone are more common than malignant ones

Question 50

What are the primary bone neoplasms?

Answer 50

• Osteoma
• Ossifying fibroma
• Osteosarcoma
• Chondroma
• Chondrosarcoma’
• Multilobular tumor of bone

Question 51

What primary bone neoplasm is seen in this image?

Answer 51

• Osteoma

Question 52

What is the most common primary tumor of dogs and cats? What dog breeds have the highest incidences? What is the mean age affected? What sex is it most common in?

Answer 52

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

Question 53

Where are the common predilection sites of osteosarcomas?

Answer 53

• Close to the knee away from the elbow

Question 54

What is seen in this image?

Answer 54

Osteosarcoma

Question 55

What animals are more prone to ossifying fibromas?

Answer 55

• Ossifying fibroma are more common in the mandibles of horses.

Question 56

What is seen in this image?

Answer 56

Osteosarcoma

Question 57

What is a chondrosarcoma? What percent of primary bone tumors in dogs is it? Is it in other domestic animals? Where is it usually found?

Answer 57

• 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

Question 58

What is seen in this image?

Answer 58

Chondrosarcoma, skull, dog -McGavin
Image on the Left: Dog was definitely experiencing significant clinical signs (neurological) due to the degree of compression of the brain. Area is locally invasive, not well demarcated, indicates malignant tumor (chondrosarcoma). Growing into the sinuses as well. If you were seeing this in person you can see some shiny tissue since the tumor is made of cartilage.

Question 59

What is seen in this image?

Answer 59

Chondrosarcoma, rib, cat

Image on right: Cat rib -> seen that it is locally invasive/ infiltrative and extensive. Marked effacement/ destruction of the rib
( chondrosarcoma)

Question 60

Is it difficult to determine the difference between an osteosarcoma and a chondrosarcoma grossly? How can you?

Answer 60

• Osteosarcoma: More bone proliferation then cartilage but can have cartilage.
• Chondrosarcoma: More cartilage proliferation than bone. Can have bone proliferation though.
• Sometimes hard to distinguish between these two cancers due to the similarities.