Pathology of Bone - Part 2 Flashcards
Lead poisoning: Lead interferes with _______ activity.
Subtle bone lesions –> Increase bone _____ (_______) in the _______ –> “_____ line”
osteoclastic, density, osteosclerosis, metaphysis, lead
Associate lead with neurological problems. Animals, especially cattle, can get into oil from tractors, old batteries (lead apparently is sweet) –> neurologic necrosis/encepalopathy.
Metaphyseal osteosclerosis, lamb,
Lead poisoning. From Jubb, Kennedy &
Palmer’s pathology of Domestic Animals-
Grant Maxie ed., 2007
After the exposure to lead, there is a focal area of osteosclerosis. This line can be recognized by radiologists because they see this line of increased bone density which is characteristic of lead toxicity.
Hypervitaminosis A: The most well known syndrome is observed in ____ that consume high quantities of ____ ____ (high vitamin __ content) for a ____ period of time –> deforming ______ ______.
cats, bovine livers, A, long, cervical spondylosis
Bone lesions produced as a result.
Spondylosis is degeneration of vertebral bodies. In this case, cats that are suffering from hypervitaminosis A or Vitamin A toxicity can develop cervical spongilosis. Can produce lameness, neurological signs, compression of nerves in the area –> lamness.
Seen primarily in Austraila and Urugauy, but can also be seen here, where animals are slaughtered away from major cities. Killed in field, feed liver to cats –> unfortunately, excessive amounts of vitamin A in fresh liver produces changes in bone.
This disease is more common in Australia and Uruguay
Hypervitaminosis A
Cats affected by Hypervitaminosis A develop ______ formation around the ___ of the _____ vertebrae, _____ and ____.
osteophyte, joints, cervical, shoulder, elbow
Hypervitaminosis A is also known as?
ankylosing spondylosis or disseminating ankylosing osteoarthropathy).
Label this image
Ankylosis = fixation of a joint. Called this because degenerative changes you will see in cervical vertebrae results in production of osteofites. Nodules of new bone that are formed on the periosteal surface of the vertebra. Extends to adjacent vertebrae and produces fixation of vertebrae. Involve foramina where spinal nerves exit –> neurological issues.
Necrosis (Osteonecrosis or _____), means ______ ______ and is the result of ______ injury.
, Osteosis, bone necrosis, ischemic
Osteonecrosis is often the result of _____ but may also occur in _____ and _____ bone disease. Necrotic bone appears ____.
trauma, inflammatory, neoplastic, paler
In cases of osteonecrosis or osteosis, microscopically you will see cell ____ with loss of ______ from their ____.
death, osteocytes, lacunae
What is the outcome of osteonecrosis?
- Depends on the quality of the collateral circulation. 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 collateral circulation is well preserved/salvageable.
- If collateral circulation is not well preserved/salvageable –> Formation of a “sequestrum” –> A piece of necrotic bone isolated from the remaining viable bone. E.g. in horses –> surgeons must remove the necrotic bone to stimulate proliferation of adjacent bone aka healing.
Attempts to wall off a sequestrum will result in the formation of a layer of ______ tissue and _____ bone known as an “______”.
granulation, reactive, involucrum
Foal, focal osteomyelitis (inflammation of bone - used b/c inflammation of bone marrow in addition to the bone itself) with sequestrum.
Distal end of a long bone.
Granular type of appearance; bottom is pale in comparison to top. Body makes an attempt to surround area of necrosis to initiate repair –> proliferation of granular tissue (light brown region above pale part). This tissue is called the involucrum.
A traumatic bone fracture occurs when a _______/_______ bone is broken by ______ _____.
normal/healthy, excessive force
A pathologic bone fracture is when an _______ bone is broken by _____ trauma or ____ weight bearing.
abnormal, minimal, normal
Can also be seen in animals with bone tumors. Neoplasm in bone –> weakens bone –> minor trauma –> pathological fracture.
Complete or Incomplete is a type of?
bone fracture
Complete separation = complete transection of a bone
Closed (simple) or Open (compound) is a type of?
Bone fracture
Closed = fracture of the bone but soft tissue around it, including the skin, is intact.
Open = severe trauma –> pieces of bone rupture through the skin.
- prognosis is more complicated because susceptible to secondary bacterial infection b/c bone marrow is exposed, severe damage of soft tissue.
Comminuted is a type of
bone fracture
Bone breaks into several small fragments. E.g. race horse -> does not end well.
Avulsed bone fractures are caused by the pull of a _____/muscle _______ at its _____ into bone
ligament, tendon, insertion
Tendons of muscle attached to periosteal surface. In seevere traum, pulling of area –> bone comes out with part of the tendon.
Microfracture/ infraction bone fractures occure due to fracturing of _____ without ______ deformation of _______ bone.
trabeculae, external, cortical
Osteodystrophies can result in microfracture (compressive fractures of vertbrae with osteoperosis; weight bearing –> fracture of trabeculae of cancellous bone which is an example of microfracture).
Morphological diagnosis?
Pig – vertebral abscess resulted in fracture of the vertebral body
and focal compression of the spinal cord, common sequel of tail
biting.
Pig was doing well, fed them, very excited/fighting for food. All of a sudden, find one of the pigs laying down on floor unable to stand with posterior paralysis. This is the typical presentation. When do autopsy, find presence of vertebral abscess. Suppurative inflammation –> Suppurative osteomyelitis/ Vertebral osteomyelitis. Loss of bone here.
Morpholoical Diagnosis = vertebral abscess OR focal suppurative vertebral osetomyelitis.
In pigs, this is a common sequel of tail biting. Infection in tail travels through blood vessels into vetrebrae –> abscess production
Cornell, Dr. King’s show & Tell. Pathologic fracture,
Osteosarcoma, dog
Relatively common in dogs (malignant).
One of the presentations is that the animals may become acutely lame b/c you may have a pathological fracture.
Bone becomes weak due to proliferative tumor.
Fracture repair
Bone usually has a very good healing capability, especially in younger individuals. With age, when get a fracture, it is more complicated (from 70s onward).
Read this part in your reference book
Whenever you have a complete fracture of a long bone, immediately after fracture you see the formation of a hematoma aka large blood clot. Hematoma builds a meshwork to facilitate the arrival of fibroblasts and new blood vessels. Also have MQ, some inflammatory cells trying to reabsorb necrotic debris, etc. that will result in osteoprogenitor cells that you see in the endiosteum and periosteum. Later on, more than a week later, you will see osteoprog → osteo blasts → build woven bone → repair starts. These osteoprog can also build cartilage. With time, this cartilage is completely replaced by bone and may have complete healing of fracture. Also important to maintain stability of fracture so that the healing process happens well. More mobility = less proper vascularization in the area. Instead of having lots of osteprog -→ more fibroblasts to produce more CT because more resistant to hypoxia.
Healed fracture
In addition to an adequate blood supply, stability of bone fragments is of prime importance in fracture repair
Focal area completely replaced by bone.
May see even after years that there is a nodular change in ribs because healing was not achieve properly.
What are complications associated with bone
fractures?
- Bone necrosis (severe fracture → severe damage to blood vessels → focal areas of hemorrhage and areas of severe hypoxia → not achieve complete vascular degeneration in those areas → formation of a sequestrum (depending on location, surgically have to remove necrotic area to stimulate healthy bone proliferation and repair.
- Nonunion fracture → pseudoarthrosis (false joint) formation. Seen sometimes in wildlife.
- Osteomyelitis (compound fractures) → pieces of bone come out of skin and it took awhile for animal to go to et → develop osteomyeltiis. Even with antibiotic treatment → severe issues
- Cachexia; especally in wildlife, if tehy have fractures/lesions, unable to feed themselves.
non union fracture that healed primarily with CT.
With time, there is the formation of a cavity in this area that can be lined with synovial membranes.
Can move these areas around.
Inflammation of the bone is also called?
Osteitis/ Osteomyelitis
Inflammation of the bone is also associated with inflammation of the bone marrow, hence why we should use ostemyelitis.
Aseptic inflammation –> trauma may cause ______ with formation of exostosis (_______).
osteoperiostitis, osteophytes (nodules containing bone that are located usually on periosteal surface of the bone).
The more common cause of osteitis is bacterial infection.
Infection: Local or systemic (hematogenous route)
Noenatal infection → sepsis
Bacteria circulating in the blood, can localize in the bone, and produce osteomyelitis. When we get neonatal cases in farm animals, during post mortem exam split seveal long bones to detect presence of osteomyelitis.
most lesions of osteomyleiic in young animals is in the metaphysis immmediately underneath the growth plate. Why? B/c blood vessels coming from diaphysis come all the way close to the physis, turn around in a hsarp angle. B/c of angle, slowing down of blood in thia area, blood vessels are very thin, facilitate change of nutrients with growth plates, etc. so a bit leaky; Bacteria circulating in the blood has ability to come out into areasw → proliferate → osteomyeltisi → prliferate → suppurative (neutrophilic inflammation) exudate. Looks pale grossly, formation of cavities containing puss.
Starts in metahysis, can spread to adjacent tissues, drain into the skin (fistulus tracks) b/c all of the proteolytic enzyes produced by neutrophils produced destruction of tissue. Inflammatory process from the bone extends into joints → supurative arhtriit.s. Foals with osteomyleitis can produce polyarthririst (swollen, large, carpal joints).
Physitis has extended to the periosteum
and metacarpal phalangeal joint, foal
Primarily in young individuals (see growth plate hence why we know young). See focal area of pallor surrounded by red ring representing acute inflammation. Growth plate in this case is primarily gone.
Embolic osteomyelitis, foal. Note
Area of bone necrosis (arrow)
See growth plate. Look in metaphysis immediately undeer growth plate, look for pale discoloration. See a small white dot = necrosis that is demarcated by reddish rim of inflammatory cells.
Salmonella, e.coli can produce these types of lesions. Must culture to come up with diagnosis. Salmonella is important, especialy in foals.
Bovine Actinomycosis, “lumpy jaw”,
suppurative inflammation of mandible in cattle.
Lesions in oral cavity → bacteria penetreate into mandible →
Present with large mandible that is nodular. Presence of fistulus tracks draining onto surface of skin → alopecia.
Bovine Actinomycosis, (“lumpy jaw”), - involvement of left
maxilla UCVM
Suppurative exudate is very characteristic of this.
Chronic pyogranulomatous osteomyelitis –
Actinomycosis, UCVM, OI
Markedly large
Presence of supurative exudate
Defacement of normal architecture of nasal cavity. Bacteria produce chronic supurative and pyogranulomatous inflammation. Priliferation of neutrophils, MQ, multi nucleated giant cells, fibrosis, severe bone damage → all seen in actinomyosis
Actinomyosis
Gram positive, filamentous bacteria
Port of entry = usually this organism enters through local lesions in the oral cavity that allows the bacteria to penetrate in between the teeth ang gum -→ osteomyolitis. This is a chronic conditionn resulting in pyogranulomatous inflammation. Neutrophils with viable numbers of MQ, multinucleated giant cells → destroys the bones. Lesions located in jaw and maxilla.
What can be seen here?
Pyogranulomatous
Osteomyelitis, Actinomycosis → Affects hard tissue like the bone.
neutrophils, MQ
What can be seen here?
Splendore Hoeppli
Dark pruple = bacteria colony
Splenodre hoeppli = position of Ab/Ig complex. Characteristic of Actino
Sulfur granules is an important feature of this disease.
What can be seen here?
Gram stain of lesions: Gram positive bacteria, Actinomyces bovis, UCVM, OI
Filamentous
What can be seen here
“Lumpy Jaw” (Actinomycosis) – cow.
Actinomyces bovis. Note osteolysis of the macerated and bleached bone specimen
Macerate this bone, this is how it will look. Produces severe damage of bone. Bone lysis in lesions and bone proliferation occurring simultaneously. Suppurative exudate can be seen on the surface.
The disease is also occasionally observed. In young dogs with rhabdomyosarcomas of the urinary bladder and mares with
ovarian tumors.
Radius, ulna, metacarpals; newly produced bone on the surface of the periosteum. This is a characteristic lesion of this disease.
Bladder? Text caroline
What condition may this dog breed have?
West Highland White Terrier
Lion Jaw
Animals usually have to be euthanized if lesions are so severe taht tehy can not eat.
Canine craniomandibular osteopathy (“Lion Jaw”)
Osteofites of new bone seen on periosteal surface.
Occipital bone, tympanic bulla can also be affected
What can be seen here?
Osteoma, maxilla,
Sheep-McGavin
Enlargement of maxilla; is not infiltrating outside area; osteoma
Can see a bot = chronic rhinitis in sheep; live in sinuses. CAn live in molar area and produce meningitis?
In the dog osteosarcoma has a relatively specific site predilection:
“Close to the knee and away from the elbow”
Predilection sites: practically from every bone in the body, but when you divde axial = cervical columbn or appendicular
appendicular is more common
Humerus = 15%
distal radius and ulna = 28%
What can be seen here?
Osteosarcoma, 11 y-old
Female Rottweiller
Distal radius, ulna
Eventually dog became very lame → clinical signs → euthanized
Osteosarcoma, 11 y-old
Female Rottweiller
Presence of proliferative lesion in radius and ulna
Producing osteod
Areas of loss of densitty can be seen sometimes too.
Animals rarely survive more than 1 year. Prognosis is not good. Usually remove the leg. Need to make sure tumor has not metastaized. Eventually die of metatastic disease.
What can be seen here
Osteosarcoma, 2 year-old Poodle, Atlantic Veterinary College,
Lesion in distal femur
Proliferative lesion around bone infiltrates into medullary cavity.
Difficult to see very much because malignant tumors do not have clear boundaries.
nodular proliferation is hard. Osteoblasts producing osteod can also is soft so can also find this here. ?
Need to do histology to determine is osteosarcoma or fibrosarcoma.
Waht can be seen here
Chondrosarcoma, skull, dog
Lesion is not benign; compressing underlying brain. Severe neurological signs.
tumor appears to be also ifiltrating the frontal sinus; not confined to particular area.
In this area see shiny tissue representing cartilage; arising in flat bone so very likely we are dealing with chondrosarcoma (can have areas of bone prolfieration) osteosarcoma can have areas of cartilage. Based on knowing that you can diagnose which tumor type it is
Chondrosarcoma, rib, cat, Zachary (ed.),
Pathologic Basis of Veterinary Disease, 2017
