Analysis of joint fluid, CSF, and respiratory tract washes

Question 1

Technique for joint taps

Answer 1

Sedation or anaesthesia normally needed

Sterile technique - clip, clean, prep

Should only have small amount of fluid, normally of a gel like consistency

First drop should be put on a couple of glass slides for cytology smears

The rest into EDTA for cytology and protein evaluation and plain tube for culture

Question 2

Componenents of joint fluid analysis

Answer 2

Evaluate the appearances and viscosity

Cytology of direct smears

(Automated cell count)
(Fluid protein concentration)
(Mucin clot test)

Question 3

Normal joint fluid protein levels

Answer 3

Determined using refractomer

Usually <25g/L but up to 30 has been reported

Question 4

Mucin clot test

Answer 4

At external labs

Addition of acetic acid to joint fluid taps which forms a clot

Formation of clot reduced by addition of hyaluronic acid e.g. in inflammatory or degenerative joint disease

Question 5

Normal joint fluid

Answer 5

Clear to pale straw in colour

Viscous

Thixotropic properties where it is less viscous when shaken and returns to normal gel like ocnsistency when standing

Question 6

Normal joint fluid on cytology

Answer 6

Thick pink background

Low numbers of nucleated cells (<1 - 3 x 10^9/L), predominantly monomuclear cells e.g. lymphocytes, macrophages, synoviocytes, and very few neutrophils

Cells often demonsrtate windrowing which confirms that it is viscous

Question 7

Classifications of joint fluids

Answer 7

Normal

Consistent with degenerative arthropathy

Consistent with inflammatory arthropathy

Question 8

Conditions that prduce a degenerative arthropathy

Answer 8

Osteoarthritis

Osteochondrosis

Trauma

Joint instability

Question 9

Degenerative arthropathy joint tap

Answer 9

Increased cellularity ( > 1-2 nucleated cells per hpf), predominantly mononuclear cells (macrophages and synoviocytes)

Hyperplasia of the synovium leads to increased numbers of synoviocytes

Thick pink background and windrowing of cells still present

Question 10

Infectious causes of inflammatory arthropathy

Answer 10

Bacterial infection

Spirochaetal infection (e.g. Borrelia)

Rickettsial infection (E.g. anaplasma, ehrlichia)

Protozoal infection (e.g. Leishmania)

Question 11

Non-infectious causes of inflammatory arthropathy

Answer 11

Immune mediated polyarthritis (IMPA)

Breed associated polyarthritis

Systemic lupus erythematosus

Erosive diseases (e.g. rheumatoid arthritis

Question 12

Cytology of inflammatory arthropathy

Answer 12

Increased cellularity (>1-2 nucleated cells per hpf)
Predominantly neutrophils

Rare to see infectious agent

Often there is loss of thick pink background and the cells do not show windrowing, and mucin clot test is often poor

Question 13

Septic (bacterial arthritis)

Answer 13

Usually associated with trauma - direct innoculation into the joint, or with haematogenous spread

If trauma then only affects one joint, if haematogenous can be multiple

Culture is poorly sensitive

Question 14

Immune mediated polyarthritis

Answer 14

Inflammatory disorder

Usually associated with multiple joints, particularly the smaller distal joints

Often idiopathic in origin, can be secondary to administration of some drugs (TMPS) or vaccines (feline calicivirus vaccine)

Diagnosis of exclusion

Question 15

Diagnosis if joint tap has <1-2 cells per hpf, which are mostly mononuclear?

Answer 15

Likely normal

Question 16

Diagnosis if joint tap has > 2 cells per hpf, which are mostly mononuclear?

Answer 16

Degenerative arthropathy

Question 17

Diagnosis if joint tap has > 2 cells per hpf, which are >10% neutrophils?

Answer 17

Inflammatory arthropathy, infectious or non-infectious

Question 18

Formation of CSF

Answer 18

Ultrafiltration and secretion through the choroid plexus of lateral, third and fourth ventricles

Secretion by ependymal cells lining the ventricles

Ultrafiltration across blood vessels around subarachnoid space and within pia mater

Question 19

Technique for CSF tap

Answer 19

General anaesthesia

Sterile technique - Clip, clean, prep

Contraindicated if increased intracranial pressure due to risk of herniation

Collected at cerebromedullary or lumbar cisterns

Removal of up to 4-5ml possible in dogs, up to 1ml in adult cats

Place in EDTA tube for cytology and plain tube for culture

Cells lyse quickly due to low protein conc so need to prepare for cytology and cell count quickly (30-60mins)

Question 20

Components of CSF analysis

Answer 20

Evaluation of colour

Nucleated cell count

Red blood cell count

CSF protein (microprotein) - measures low amounts of protein in a sample

Cytology

Question 21

Nucleated and red cell counts in CSF

Answer 21

Below limit of detection for most automated analysers, use a haemocytometer instead

Difficult to differentiate white and red cells

Question 22

CSF protein concentration

Answer 22

Too low to be measured using a refractometer, instead use a microprotein assay

Urine dipsticks can give indication whether it is normal or increased (normal should be trace or +1)

Question 23

CSF cytology

Answer 23

Too low a cell count for that to be useful, so concentrate a larger amount of CSF onto one area of the slide

Question 24

Classification of CSF analysis

Answer 24

Normal

Albuminocytological dissociation

Neutrophilic pleocytosis

Mononuclear pleocytosis

Question 25

Normal CSF

Answer 25

Clear and colourless Low protein concentration (<0.3 g/L in CSF taken from the cerebromedullary cistern and <0.45 g/L in CSF taken from the lumbar cistern) Nucleated cell count is also usually low <5 cells/µL. Mixed population of small and large mononuclear cells (lymphocytes and monocytoid cells), rare neutrophils, occasional ependymal cells

Question 26

CSF haemorrhage

Answer 26

Diagnosed based on the colour of the CSF (yellow or xanthochromic) Presence of macrophages containing haemoglobic breakown products (haemosiderin and haematoidin)

Question 27

Albuminocytological dissociation

Answer 27

CSF has an increased protein concentration but normal nucleated cell count Associated with increased permeability of BBB Non-specific and seen in inflammatory, degenerative, compressive, or neoplastic disorders

Question 28

Neutrophilic pleocytosis

Answer 28

Increased CSF nuncleated cell count, predominance of neutrophils Appearance of neutrophils can be helpful since the presence of degenerate neutrophils will increase the index of suspicion for bacterial infection/meningitis

Question 29

What diseases are associated with a neutrophilic pleocytosis (CSF)?

Answer 29

Bacterial meningitis Steroid responsive meningitis arteritis (SRMA) Other infectious causes (fungal, protozoal) Neoplasia or degenerative diseases

Question 30

Bacterial meningitis

Answer 30

Uncommon in small animals When bacteria gains access to CSF either directly, by local or haematogenous spread Variable clinical signs - often depressed and painful Usually associated with marked neutrophic pleocytosis with some degenerative changes Rare to see bacteria

Question 31

Steroid responsive meningitis arteritis

Answer 31

Young to middle aged dogs Boxers, Beagles, and Burnese Mountain dogs predisposed Present with pyrexia, depression, and neck pain Mild to marked neutrophilic pleocytosis with non-degenerate neutrophils

Question 32

Mononuclear pleocytosis causes (CSF)

Answer 32

MUO Protozoal infection (Toxo/Neospora) Other infectious causes e.g. fungal Neoplasia Degenerate diseases

Question 33

MUO

Answer 33

A non-spetic inflammatory disease of the CNS Affects young to middle aged, female dogs, small and terrier breeds predisposed Variable clinical signs e.g. seizures, ataxia, pyrexia

Question 34

Diagnosis of nucleated cell count is <5 cells/uL, and CSF protein <0.3-0.45 g/L?

Answer 34

Likely normal

Question 35

Diagnosis of nucleated cell count is <5 cells/uL, and CSF protein >0.3-0.45 g/L?

Answer 35

Albuminocytological dissociation

Question 36

Diagnosis of nucleated cell count is >5 cells/uL, that are mostly mononuclear cells?

Answer 36

Mononuclear pleocytosis - MUO - protozoal infection - etc.

Question 37

Diagnosis of nucleated cell count is >5 cells/uL, and more than 10% neutrophils?

Answer 37

Neutrophilic pleocytosis - bacterial infection - SRMA - etc.

Question 38

Technique for respiratory tract wash

Answer 38

May require GA Usually collected via bronchoscope or ET tube Tracheal washes on sample the trachea, BAL samples the lower airways and alveoli Warmed sterile saline instilled into airway and as much as possible aspirated back Placed in EDTA tube for cytology and plain tube for culture

Question 39

Main classifications from a respiratory wash

Answer 39

Normal/unremarkable Neutrophilic inflammation Eosinophillic inflammation Haemorrhage (Neoplasia - uncommon)

Question 40

Normal respiratory wash characteristics

Answer 40

Low cellularity - ciliated columnar epithelial cells (TW) - Cuboidal epithelial cells (BAL) - Alveolar macrophages predominant - Low numbers of neutrophils - Eosinophils rare in dogs but more numerous in cats - Rare goblet cells and mucin granules May see oral contaminants: squamous epithelial cells, Simonsiella bacteria

Question 41

Neutrophilic inflammation on respiratory tract wash

Answer 41

Presence of >10% neutrophils If degenerate - suspect bacterial infection, or old sample May see intracellular bacteria Usually bacterial infection, but could be other infections like viral, protozoal, foreign bodies Should do culture

Question 42

Eosinophilic inflammation of respiratory

Answer 42

Numbers of eosinophils are increased (>10% in dogs, >25% in cats) ALso increased mast cells, plasma cells, and lymphocytes May be associated with peripheral blood eosinophilia Can be caused by parasites (Angiostrongylus vasorum), hypersensitivity or allergic disease (feline asthma), eosinophilic bronchopneumopathy Rarely caused by other infections or neoplasia

Question 43

Most useful findings on equine BALs

Answer 43

Neutrophilic inflammation Haemorrhage

Question 44

Neutrophilic inflammation in equine BALs

Answer 44

Can be septic (e.g. Bacterial, fungal) or non-septic Most common causes are equine asthma syndrome - Severe (RAO, COPD, heaves): common in mature horses, increased effort at rest, coughing, exercise intolerance, neutrophilic BAL and increased mucus - Mild to moderate (IAD): any age, subtle clinical signs at rest, increased neutrophils, lymphocytes, eosinophils, and mast cells Difficult to differentiate on cytology, BAL recommended to rule out concurrent septic causes

Question 45

Haemorrhage on equine BAL

Answer 45

Can indicate exercise induced pulmonary haemorrhage (EIPH) Occurs following strenuous exercise On cytology may be large numbers of erythrocytes, can diagnose EIPH if macrophages containing haemosiderin seen in large numbers