Patters of Disease: Synovial Joints & CNS

Question 1

Arthritis

Answer 1

lesions in articular cartilage in addition to inflammation of the synovial membrane.

Question 2

Synovitis

Answer 2

inflammation of the synovium only.

Question 3

What are the 5 portals of entry into joints?

Answer 3

1. Hematogenous
2. Extension from osteomyelitis
3. Extension from adjacent soft tissue infection
4. Diagnostic procedures
5. Penetrating damage (puncture)

Question 4

Hematogenous entry into joint space.

Answer 4

Neonatal bacteremia secondary to omphalitis (umbilical infx) or oral-intestinal entry leads to POLYARTHRITIS = JOINT ILL.

Question 5

What is Joint ill?

Answer 5

Navel or joint ill is a disease of young calves, usually less than one week of age. It occurs as a result of infection entering via the umbilical cord at, or soon after, birth. This infection can result in a range of signs depending on where the bacteria spread to.

Question 6

What are portals of entry into the CNS?

Answer 6

1. Direct.
2. Hematogenous
3. By leukocyte trafficking
4. Retrograde axonal transport.

Question 7

Describe Direct extension in the CNS and provide an example of such.

Answer 7

1. Penetrating trauma through the calvarium. An example being a bite, antler injury, or gunshot wound.
2. Penetrating trauma through the vertebral body. (ex. bite wound)
3. Extension of middle and or inner ear infection. (abscess from inner ear)
4. Extension of infection from the nasal cavity or sinus through the cribriform plate or calvarium. (Ex. Aspergillus (fungal) infection with septate hyphae)
5. Extension of nasal or sinus neoplasms through the cribriform plate or calvarium (ex. nasal carcinomas) (THIS IS NOT UNUSUAL IN DOGS)
6. Direct Extension from osteomyelitis or neoplasia of vertebral bodies extending through the vertebrae into the vertebral canal. (Ex. osteosarcoma invading vertebral body from the periosteal surface.)
7. Benign or malignant neoplasms replacing vertebra and spinal cord. (ex. osteochondroma)
8. Invasion of adjacent malignant neoplasms (ex. malignant melanoma)

Question 8

Describe Hematogenous Entry into the CNS.

Answer 8

Most common portal of entry.

Question 9

Describe how hematogenous entry affects neonates…

Answer 9

Bacteria can enter the blood via umbilical vein or through veins following surgical procedures (ex. castration)

Note: Always check the ventral surface of the brain PM. If pus is found then usually umbilical infection transmission.

Question 10

How does hematogenous entry cause meningitis?

Answer 10

Bacteria (e.coli/ streptococcus) can enter the blood stream and cause meningitis (inflammation of the leptomeninges [ arachnoid and pia mater] ).

Question 11

What methods can bacteria use to enter the CNS? Which age of animal does this usually affect?

Answer 11

1. Hematogenous
   
   • Nasal/ sinus infections can spread intracranially via the veins not just by direct extension.
2. Leukocyte trafficking.
3. Direct extension.

Neonates usually acquire bacterial infections causing inflammation of the CNS, either due to umbilical infection or castration.

Question 12

How does hematogenous transmission affect adult animals?

Answer 12

Sites of chronic inflammation where a bacterial source is sustained can enter the venous system and spread to the brain.

Examples of this sustained bacterial infection causing chronic inflammation would be:

- abscesses
- bacterial skin disease
- ear infections 
- endocarditis

Question 13

Where are abscesses most likely to form in the brain and why?

Answer 13

Cerebral Abscesses more commonly form in the grey matter of the brain v. the white matter because of disproportionate blood flow where the grey matter receives more blood than the white matter.

At the grey-white matter junction the blood flow at this region allows bacteria to attach and move through the BBB causing disruption and destruction of tissue and space occupying.

Question 14

Give an example of a bacteria that spreads hematogenously from the nasal/ sinus cavities. What species does this primarily occur in and what is the outcome of infection.

Answer 14

Occurs particularly in cattle causing pituitary abscesses.

1. Pasteurella multocida
2. Actinomyces pyogenes

Question 15

What bacteria will cause this same hematogneous outcome in horses and how does it achieve this?

Answer 15

Streptococcus equi (Strangles) will cause brain abscesses.

It will spread via the bloodstream from lymphoid tissues.

Question 16

What is TEME? What bacteria causes it, what species does it occur in, how does it achieve infection, and where does infection occur?

Answer 16

1. Thrombotic meningoencephalitis of cattle. Inflammation of the meninges and brain.
2. Histophilus somni
3. Cattle
4. Host gets a bacteremia following replication in the respiratory tract. The bacteria adhere to endothelial cells, leading to vasculitis, hemorrhage and local thrombosis.
5. This occurs at the grey-white matter junction.

Question 17

Name two Equine viruses that spread Hematogenously and what they cause.

Answer 17

1. Equine herpesvirus-1: can cause vasculitis, infarcts in spinal cord. Transferred to endothelial cells via leukocyte trafficking.
2. Equine Encephalomyelitis: replicates in endothelium first causing vasculitis and thrombosis, infects and kills neurons.

Question 18

Name one Feline virus that spreads hematogenously.

Answer 18

FIP- Feline Infectious Peritonitis (coronavirus)

Causes pyogranulomatous vasculitis obliterating the “Circle of Willis” ventral brain surface (many neutrophils involved)

Question 19

What does the presence of perivascular “cuff’s” of lymphocytes indicate? TEST QUESTION

Answer 19

Viral Infection

Question 20

What is leukocyte trafficking? Give two examples of organisms that utilize this port of entry.

Answer 20

Macrophages and lymphoid cells continually move in and out of capillary beds in the CNS. Organisms invade these CNS cells and transport into the CNS.

1. FeLV (Feline leukemia virus)
2. Blastomyces dermatitidis.

Question 21

What is retrograde axonal transport?

Answer 21

Agents replicate in richly innervated tissues (sensory receptors and motor end plates) and gain entry into the CNS via retrograde axoplasmic flow.

Question 22

What bacteria uses retrograde axonal transport? What species does this bacteria affect and what is its mechanism of infection?

Answer 22

1. Listeria monocytogenes.
2. Domestic Ruminants only
3. Enters submucosal tissue via injuries to oral mucosa. From there it travels to the CNS via sensory and motor branches of the trigeminal nerves directly to midbrain and medulla.

Listeria bacteria live in the cells and spread from cell to cell causing damaged to them via inflammatory processes. Early lesions are the focus of microglial cells but later neutrophils dominate. This causes microabscesses.

Question 23

Describe the retrograde axonal transports of rabies virus.

Answer 23

1. Replicates in muscle from being bitten.
2. Enters nerve
3. Ascends the axon
4. Dorsal root ganglion
5. Enters spinal cords
6. Ascends to rbain via ascending and descending nerve fiber tracts.
7. Enters brain.
8. Spreads to salivary glands and eye.

inoculations to head means shorter incubation time.

Question 24

Rabies causes what to the body?

Answer 24

Non suppurative polioencephalomyelitis with craniospinal ganglionitis and sialoadenitis.