Rabbit Clinical Pathology

John Chitty BVetMed CertZooMed MRCVS

Anton Vets Andover, Hants SP10 2NJ

exotics@antonvets.co.uk

Other affiliations…

…and thanks

What is clinical pathology?

• Pre-mortem changes?

• Blood

• Urine

• Faeces

• Cytology

• Histopathology?

What can clinical pathology do?

• Give you a diagnosis?

• Show you the body’s response?

• Provide further clues?

• ALWAYS TREAT THE PATIENT NOT

THE NUMBERS!

What is normal?

In-house or external laboratory? • Advantages of in-house

– Speed of result

– Clinician consistency

• Advantages of lab – QC

– Technician consistency

– Time?

• Variables – Experience of clinician/ technician

– Interest of clinician/ technician

– Technology

– Sample quality

How to handle your sample?

Essentials in-house?

• A microscope!

• Electrolytes

– Na, K, iCa

– Cl?

• PCV

• Total solids?

• Urinalysis

Bloods

• What can we do? – Haematology

– Biochemistry

– Serology

• The drawbacks – What is normal?

– Diurnal variations

– Stress

– Anaesthetic effects

– Digestion?

Effects of Stress

• …or tissue damage

• Glucose

• CK

• AST

• LDH

Diurnal Rhythm

• Bile acids

• Cholesterol

• Urea

– Both highest evening

• WBC count/ differential

– TWBC – lowest evening

– Lymphocyte – “ “ “ “ “

– Heterophil + eosinophil– opposite

Stress

• Glucose

• Heterophil/ lymphocyte distribution

Rabbit Blood Haemolyses and

Clots Quickly and Easily!

Haemolysis

• Increased

– LDH

– AST

– CK

– TP

– K

– Phos

• Reduced

– amylase

Tips on blood-taking

• Sites

– Ear

– Jugular

– Lat Saphenous (tibial)

Haematology

• Red Cell Counts/ Morphology

• White Cell counts/ Differential/ Morphology

• EDTA

• Smear

Red Cells

• PCV vs HCT

• Anaemia?

• Pet rabbits often

lower PCV

• Haemoconcentration

>45%

• Anaemia <30%

Regenerative vs Non-

Regenerative?

But rabbit RBC’s have short lifespan..

….therefore often see polychromasia &

anisocytosis and up to 4% reticulocytes

Regenerative vs non-regenerative

• Regenerative

– Blood loss

– Uterine AC/ aneurysm

– Gut loss

– Parasites?

– Wounds?

– Avermectin toxicity

– Lead toxicity

– Haemolysis

• Non-regenerative

– Reduced production

– Toxins?

– CHRONIC DISEASE!!!

– PAIN!!!!

WBC

• Increase rare

– Mild in some

INFLAMMATION!!!!

– Large increases in

lymphosarcoma???

• Reduction common

– Chronic infection

– Toxaemia

– Viral infection

Heterophil or neutrophil?

Look at relative numbers….

60:40 L:H

Morphology

• Bands and left shift rare

• Toxicity

• Don’t forget..

– Diurnal variation

– Stress haemogram

Lymphocyte

• Increase

– Viral?

– Lymphoma?

• Reduction-

– Stress

– Infection

– Chronic illness

– Age?

Monocyte

• Chronic inflammation

• Check morphology!

Eosinophilia

• How do you judge

reduction?

• Increase

– Parasites???

– Hypersensitivity????

– Modulate mast cells!

Basophilia

• Often lots

• Consider with eosinophils?

• Both increased – Skin disease

– Purulent infection of certain tissues

• No eosinophilia – Liver disease?

– Hyperlipoproteinaemia

– DM

– Nephrosis

Biochemistries

• Normal?

• Normal variations?

• Sensitivity vs specificity

• DO THEY ACTUALLY HELP?????

Glucose

• LOW

– Debility

– Moribund?

– Ketosis

• HIGH

– Stress?

– Eating?

– DM???

• Rabbits get stress hyperglycaemia

• The more severe the gut problem, the

more the pain

• The more the pain, the more the stress

• The more the stress, the higher the

glucose

• ie glucose is a prognostic and diagnostic

indicator

Glucose as a gut prognostic?

• <4 – malnutrition?

• 8-15- normal/ average stress

• 15-20 – monitor!

• 20-25- prob surgical

• >25 – reach for the scalpel!

Levels

Is sodium better?

• Linked?

• How specific are they?

• Effects of sodium on fusus coli?

• Always reassess

• Always radiograph!

Lactate

• Similar levels to other mammals

• Can be measured patientside

• Acid-base?

• Possibility of detecting subclinical resp

disease??

• Relationship to caecotrophy and digestive

variations?

• NOT circadian

Prognostic?

• Persistently low may indicate impaired

caecotrophy?

• Rise of > 1.5mmol/l between 12h post-

arrival and 24-48hr post arrival gives fair

prognosis?

Proteins

• Total vs Albumin vs Globulin

• Breed and gender and age effects?

• Feeding?

• How is it measured?

• A:G ratio? 60:40

Total Protein

• Increase

– Dehydration/

hypovolaemia

– Pregnancy/ breeding

– Chronic disease

– Artefact of difficult

blood take

• Decrease

– Starvation

– Protein loss

– Malnutrition

– Stress

Albumin

• Reduction

– Failure to absorb

– Failure to process

– Increased loss

– Increased breakdown

• Increase

– Dehydration

– Hypovolaemia

Globulins

• Pregnancy

• Inflammatory disease

• Lipaemia

• ELECTROPHORESIS

– Alpha

– Beta

– Gamma

Liver

• Enzymes show hepatocellular damage? – ALT/AST/GGT/LDH/ALKP

– Or….

• Bile acids show function changes – Diurnal variation

– Dynamic tests

• Cholesterol – Useful in lipidosis

– Beta-HB

– TG?

Kidneys

• Urea – Pre-renal effects

– Post-renal effects

– Diet

– Diurnal

• Creatinine – Sensitive?

• Amylase

• GGT

• Phosphate

Electrolytes

• Calcium

– Total vs ionised

– Consider with phosphate?

• Potassium

• Sodium

• Chloride

• Consider as essential in considering weak/

collapsed rabbit and in deciding fluids

Potassium

• Low

– Anorexia

– Alkalosis

– Losses – eg saliva

– RF

– Diarrhoea

– Artefact

• High Pr/ lipaemia

– FLOPPY RABBIT

SYNDROME??

• High

– RF

– Post-renal

– Acidosis

– Artefact

• haemolysis

Serology

• Serology gives diagnosis?

• Serology shows exposure?

• Serology increases index of suspicion?

Paired serology

• Fourfold increases in paired samples show

active infection?

Treponema

• 25% positive

• Lesions before

antibody?

• Antibody may persist

• Antibody may decline

post-therapy

• Adjunct to other

diagnostic measures?

• Use as screening?

Pasteurella

• What is the point of

serological testing

against a normal

commensal?

• What will you do if

you get a positive?

• Is it worth screening?

E cuniculi

• Difficult diagnosis – can serology help?

• Rabbit titres fluctuate NOT necessarily rise

• Methodology varies

• Sensitivity varies

• Immune response varies

• Detectable antibody 3-4 weeks post-infection

• High levels 6-9 week post-infection

• Signs linked to cellular rupture and immune reaction

IgM vs IgG

• IgG background Ab

• IgM produced more rapidly in infection/

recrudescence

So....

• IgG & IgM negative

• IgG pos & IgM neg

• IgG neg & IgM pos

• IgG & IgM pos

• Rule-out

• Should be

background

• V recent infection

• Should be diagnostic?

Unless the IgM declines before

signs...

E cuniculi diagnosis

• Signs

• Rule-out

• Is it concurrent?

• Response to therapy?

• Serology?

• PCR?

– Urine – spores shed 1-3 mth post-infection

– CSF/ other tissues

– Effect of recrudescence????

Urine

• Gross appearance

helpful?

• Crystals?

– Remember pH

• Collection method

• Bacteriology?

• Cytology?

Are bacteria important without

cytological changes?

Faeces

• Gross appearance!

• Parasitology?

• Bacteriology?

• Cytology?

Bacteriology/ sensitivity

• Likely to find pathogens?

• Likely to find commensals?

• Likely to get contamination?

• Likely to find anything?

• Aerobic vs anaerobic

• Significance of results?

Bacteriology/ sensitivity:

should you do it?

• Consider in:

– Antibiotic “failure”

– Colony “outbreaks”

• How?

Antibiotic Failure

• Consider

– Dose rate

– Penetration of drug

– Drug activity

– Failure of culture/ sensitivity

– Underlying causes

– Chronicity

Culturing Pasteurella

• In healthy rabbit

– No significance

– DO NOT use

prophylactic antibiotic

– Consider other rabbits

• Diseased rabbit

– Young or in colony

• May be significant

• Consider health status

of others

– Older or individual

rabbit

• Significant?

• Consider underlying

causes

Cytology

• Quick

• Simple

• Cheap

• Shows cellular reaction to organisms

• More sensitive than bacteriology?

• Can you base therapy on it?

Summary

• There are few definitive answers

• Clinical pathology is not a short cut

• It cannot replace other clinical modalities

• It can help rule-out some conditions

• It can help confirm diagnosis

• It can help direct clinical investigation

• It can help give prognosis