Investigating Joint Disease (La Fuente)

Question 1

What is joint fluid?

Answer 1

Dyalisate from plasma

• 2 filters, vascular endothelium and synovial interstitum
• contains proteins , electrolytes, enzymes, water and HA
• cells- synovial lining cells

Question 2

How does a healthy joint differ from an inflamed joint? LOOK AT SLIDE

Answer 2

• excessive synovial fluid in joint cavity
• surrounding soft tissue inflammation
• WBCs and inflammatory mediators released into synovial fluid via inflamed synovial membrane
• normal articular cartilage

Question 3

Which inflammatory cell is more commonly seen in joint fluid?

Answer 3

Macrophages more than neutrophils

Question 4

What aspects of the Hx are important for joint dz?

Answer 4

• single v multiple limb
• intermittent v before/after excercise
• excercise tolerance
• travel Hx
• parasites
• systemic disease (IMHA, ITP etc)

Question 5

What clues may the signalment give for joint disease?

Answer 5

>age 
- puppies: instability
- senior: OA 
> breed 
- GSD hip dysplaisa 
- Labrador elbow dysplasia 
- greyhounds erosive joint disease

Question 6

What type of lameness does crucial element rupture give?

Answer 6

Weight bearing (unless traumatic)

Question 7

How may poly arthritis cases sit?

Answer 7

Not flexing any joints - sit on lateral aspects of HLs

Question 8

What clinical signs may be seen with joint dz?

Answer 8

>Lamenss 
- one or multiple limbs 
- severity 
- specific posture 
>systemic signs (variable) 
- fever
- lethargy
- anorexia 
- collapse 
> PE 
- fever
- murmur
- masses 
> orthopeadic examination
- joint effusion/buttress/muscle atrophy 
- pain/heat/decreased ROM
- instability (CCLR, CHD) crepitus  
> neuro exam 
- normal v deficits

Question 9

What is a buttress?

Answer 9

Swelling medial aspect of the stifle d/t cruciate rupture and joint capsule swelling

Question 10

Dxx for joint dz

Answer 10

>Radiographs
- joint capsule and space (look for cloudy joint effusion) 
- bony relationships 
- bone density 
- subchondral bone 
- calcification 
- osteophytes and enthesiophytes 
>arthrocentesis
- single affected joint 
- or suspected polyarthropathy (at least 3 joints) 
- sedation or GA
- sterile procedure 
- slides, EDTA, blood culture (may be false negatives for septic arthritis, blood culture medium ^ chances of success) 
> and analysis of joint fluid

Question 11

What is the cut off point for WBC in joint fluid?

Answer 11

3000
Above this = immune mediated poly arthritis OR septic
- positive culture to prove septic (rarely see bacteria in joint tap) though culture also gives false negatives

Question 12

What is analysed of the joint fluid?

Answer 12

• cell count
• cytology
• chemical analysis (TP, glucose)
• culture (R/o inflammatory septic v nnonseptic autoimmune)

Question 13

What cells can be seen on cytology?

Answer 13

> synoviocytes 
- normal 
> neutrophils
- inflammatory
- degenerate v non-degenerate
> macrophages 
- non-inflammatory (DJD)  
> bacterial/fungal hyphae 
> haemophagocytosis

Question 14

What chemical analysis can be carried out on joint fluid?

Answer 14

> glucose 
- fluid: blood = 0.8-1 normal 
- decreased in septic arthritis 
> TP
-

Question 15

If septic OA is suspected but culture negative what can be done?

Answer 15

Synovial biopsy.

Question 16

How can culture give false results? How can this be improved?

Answer 16

• false negative as culture doesn’t grow bacteria present (number too low??)
• false positive with contamination (check cell count)
  > improve by sample into special culture media
  > OR synovial membrane biopsy

Question 17

What is the most common type of infectious inflammatory OA? Aetiologies?

Answer 17

> bacteria

• dogs with OA pdf spontaneous SEPTIC OA (non weight bearing)
• direct penetration
• spread from adjacent tissues
• haematogenous

Question 18

What bacteria are most commonly involved in some tic arthritis?

Answer 18

Staph
Strep
Pasteurella
(Skin commensals)

Question 19

How long does OA take to develop radiographic signs?

Answer 19

3-4weeks

Question 20

What is seen in septic arthritis on joint tap and radiography?

Answer 20

> joint fluid 
- septic inflammation (though not always degenerate neutrophils) 
- rare bacteria 
- positive culture 
> rads 
- acute (effusion)
- chronic (degenerative changes)

Question 21

Tx septic arthritis

Answer 21

6 weeks Abx BS

Question 22

What forms of infectious immune-mediated arthritis are possible and how can you r/o?

Answer 22

> Serology and travel hx (esp Mediterranean) (NB these do not have to infect the joint, the immune complexes cause the damage)
- infectious arthritis when suspecting immune-mediated polyarthritis
Borrelia Burgdorfory (Lyme disease)
- borrelial arthritis
Ehrlichia canis (Ehrlichosis)
- rickettsial arthritis [tick not endemic UK]
Leishamania Infantum (Leishmaniasis)
- Protozoal arthritis [not endemic UK]

Question 23

What are the 2 forms of immune based arthritis ?

Answer 23

Erosive v non-erosive

Question 24

How does septic arthritis differ in presentation to immune mediated?

Answer 24

• One joint affected septically usually

- if immune mediated = poly arthritis

Question 25

Is erosive poly arthritis common? Subtypes? Most common subtype?

Answer 25

Not common!

• Rheumatoid most common within this subset
• PA greyhounds
• feline chronic progressive PA

Question 26

What is rheumatoid arthritis?

Answer 26

Auto Ab against IgG

• causes erosive poly arthritis
• radiographic changes must be present too

Question 27

What is SLE?

Answer 27

Systemic lupus erythematosis

- causes NONerosive polyarthritis

Question 28

What are the 4 MAIN types of immune mediated polyarthritis and how can these be r/o?

Answer 28

type 1: Idiopathic immune mediated poly arthritis (most common, 50% cases)
- need to r/o other subtypes) 
 type 2: infection (25%)
- serology 
 type 3: GI dz
- 
 type 4: Neoplasia
- imaging body cavities 
- depending on sigs CSF/Muscle biopsy etc.

Question 29

What test can r/o SLE?

Answer 29

ANA ( antinuclear antibodies)

- high titres with SLE, though other infectious/inflame processes can -> low titres

Question 30

What 2 types of synoviocytes ?

Answer 30

Type a and b

Question 31

Criteria for diagnosing rheumatoid arthritis in dogs

Answer 31

> 7 out of 11 criteria

• stiffness after rest
• pain 1+ joint
• stiffnes 1+ joint
• swelling in 1 additional joint within 3 months
• symmetric joint swelling
• subcut nodules over bony prominences of extensor surfaces of only rticular regions
• radiographic evidence of destructive lesions
• positive RF serum (titre >1.8)
• poor mucin content of synovial fluid
• characteristic histopath changes in synovial membranes
• characteristic histopath changes in subcut nodules

Question 32

What are the 5 main types of NON erosive immune mediated (non-infectious) inflame arthritis?

Answer 32

• SLE
• idiopathic PA
• PA/PM syndrome
• PA/meningitis syndrome
• PA akitas

Question 33

Criteria for diagnosing SLE in dogs

Answer 33

• definitive or probable depending on no. major/minor signs +- serology
  > major
• skin lesions, glomerulonephritis, polyarthritis, haemolytic anaemia, polymyositis, leukopenia, thrombocytopenia
  > minor
• PUO, CNS signs/seizures, oral ulceration, lymphadenopathy, pericarditis, pleuritis
  > serology
• ANA
• Lupus erythmatosus cell preparation