blood sampling in small mammals and reptiles

what is the circ vol of rabbits

55-70ml/kg

what is safe vol to collect from rabbit

10% of circ vol

5.5-7ml/kg

what does rabbit blood tend to do

clot quickly

• size of v, flow into syringe is slow

what tubes should be used for rabbits and what else should do

EDTA for haematology

Serum or Lithium Heparin for biochemistry

Fluoride Oxalate for glucose

• bc serum tube lowers glucose

Two fresh blood smears

what v for rabbits

Jugular → more common

Cephalic

Saphenous

Marginal ear vein (not middle artery)→ more common

where is v and a

why not use central ear a

Best to avoid using artery to avoid pinna necrosis→ would create a larger area of necrosis

higher pressure so risk haematoma

why do you still need to care with marginal ear v

•Pinna necrosis if poor/rough technique, but smaller area effected compared to artery.

difficulties of jug v in rab

Dewlap can get in the way

Restraint may inhibit respiration

Poor/rough technique may cause blindness in the ipsilateral eye

why care with restraint in saphenous v in rab

kick out and damage back

Saphenous vein restraint

blood vol of g pig

§70-75ml/kg (on average)

safe vol to sample in g pig

1% BW rule (or 10% blood volume)

when should you limit blood sample size in small mamals and exotics

if anaemic or in circulatory shock.

why is it better to use a % of total blood vol rather than bw to know how much to sample

using 10% of blood vol is a lower vol than using bw

so safer

what v use in g pig

Cephalic vein (situated more lateral)

Cranial vena cava most useful for large blood draws

when can you only do cr vena cava in g pig

under sed or ga

risk of using cr vena cava in g pig

blind

risk puncture heart

ga sed risk

blood vol rat, mouse hamster gerbil

§60-70ml/kg (on average).

safe vol to take in rat, mouse hamster gerbil

10% blood volume

locations for rat mouse gerbil hamster

Lateral tail vein - warm tail first. Not suitable in gerbils → tail slip

Lateral saphenous vein

Cranial vena cava

locations for blood sample in ferret

Jugular vein (more lateral compared to cat)

Cranial vena cava

why is less risk to do cr vena cava in ferret

heart sits further back so less risk cardiac puncture

considerations in blood sample ferret

Consider chemical restraint

Skin can be very thick especially in mature hobs

blood vol of ferret

50-70ml/kg

locations in hedgehog

Cranial vena cava

Jugular vein (hard to visualise due to thick skin)

Femoral vein (inside hind leg)

considerations when using cranial vena cava method

Potential for severe complications if performed incorrectly

In some species (e.g. guinea pig, hedgehog) the heart lies very close to sample site.

Thoracic pathology may change normal anatomy (radiograph first helps)

Anaesthesia is essential

cr vena cava method

Patient in dorsal recumbency, head extended, and forelimbs retracted caudally

25G, 0.5" needle (or similar)

Needle placed at the notch where first rib meets the manubrium (bone at top of sternum)

Advance towards the contra-lateral hindlimb

Approximate 30o angle until blood flash

what does this highlight

ferret l

g pig r

Note different in the heart’s position → risk less in ferret

why do we use landmarks in reptiles

Most veins are not visible = use landmarks and feel

why may we contam blood samples in reptiles

The lymphatic system is closely associated with blood vessels which may lead to contamination of blood samples

other issue with reptile venipuncture

Blood pressure low and blood draws slowly

why not use edta in reptiles

EDTA tends to haemolyse reptile red blood cells.

what anticoagulant in reptiles

Lithium Heparin is anticoagulant of choice

what else should be made with reptiles

Make two good quality fresh smears

how do we perform haematology in reptiles

Haematology is usually performed manually since automated techniques are made difficult due to nucleated red blood cells

why is good skin prep in reptiles important

Skin is often heavily contaminated so ensure thorough skin preparation.

• eg salmonella

what is approx circ vol of reptiles, what is safe to take

Approximately 5-8% of body weight

May collect up to 10% (i.e. 5-8ml/kg)

• BUT many reptiles are presented in poor to very poor health and are often anaemic

• Therefore, often take half this amount

• Rarely require more than 2ml

samp site in lizard

• ventral coccygeal v

• ventral abd v

• jugular

how do ventral coccygeal v in lizard

Entry approximately 1/3rd down the tail to avoid hemipenes and anal glands

Ventral or lateral approach may be used

risk of ventral coccygeal v

• necrosis (esp b dragons, iguanas)

• tail autotomy (geckos) → ga can help reduce

• 
  

  

why not use ventral abd v

Difficult to prevent haematoma

benefit of ventral abd v

§May be visualised in some species

when better to use jug v

Useful in large, longer-necked species such as Monitor lizards

risk of using jug v

Blind approach along imaginary line from dorsal ear to shoulder

• but Often quite superficial

  
  

sample sites in snakes

• ventral coccygeal v

• heart

• palatine v (can be cannulated)

when is harder to use ventral coccygeal v in snake

§Difficult in small snakes

why can we sample from heart in snake

low bp and flow in heart

• so less risk of losing blood from the hole we have created

how sample from heart in snake

Dorsal recumbency

Heart located visually, with doppler or ultrasound

Stabilise heart between finger and thumb

Needle entry ventral midline at a 30-degree angle in a cranial direction (aim for caudal point of ventricle)

always under ga

risk of palatine v

Prone to haematoma formation

how do palatine v

Large, anaesthetised snakes only

sample sites in chelonians

• jugular v

• subcarapacial v

• dorsal coccygeal v

features of using jug v in chelonians

Along line from dorsal ear scale to shoulder

Tends to be superficial

Visible in some species

Lymph contamination least likely

Carotid artery deeper and more ventral

how do subcarapacial v/sinus in chelonians

Entry point craniodorsal midline where skin joins carapace

Aim for point at junction of 1st & 2nd vertebral scute on midline

May need to bend needle slightly

Head may be retracted or extended

how do dorsal coccygeal v

Often superficial

Aim as far cranial as possible

risk of using subcarapacial v/ sinus

Often lymph contaminated

risk of using dorsal coccygeal v

Often lymph contaminated

anisocytosis

= RBCs that are unequal in size

polychromasia

high number of immature red blood cells

features of rabbit rbc

Anisocytosis and polychromasia is a common, normal finding

May be due to shorter erythrocyte life span (57-67 days)

rabbit heterophils

Heterophils have granular cytoplasm and may be mistaken for eosinophils.

• het should have rod shaped granules (eos more round)

rabbit basophils

Basophils are present quite commonly.

rabbits lymphocytes, eos, monocytes

§Lymphocytes, eosinophils and monocytes similar to dog/cat.

Representative rabbit blood cells

(A) RBCs and platelets.

(B) Heterophil

(C) Lymphocyte

(D) Eosinophil

(E) Basophil

(F) Monocyte

what happens to rabbit wbc in infection/ stress

Typically, the heterophils (neutrophil) to lymphocyte ratio is 1:1 (45%:45%).

The total white cell count rarely increases, instead the neutrophil : lymphocyte ratio changes in response to stress or disease.

Relative neutrophilia and lymphopaenia occurs with infection and chronic stress

rabbit

heterophil

what is kurloff cell in g pig

produced by the thymus under oestrogen stimulation. Resembles lymphocyte with round to oval inclusions

• is still present in male g pigs

function of kurloff cell

protect fetus from maternal immune functions

do g pigs have neutrophils or heterophils

g pigs have heterophil

ferret neutrophil

contain small, pale-red granules

ferret eosinophil

granules rounded and bright red

how are ferrets erythron diff

have higher HCT, HB, and RBC counts

how are ferrets wbc diff

White cell count generally quite low (3-4 x109)

blood groups in ferrets

no

features of blood cells in reptiles

Both cell types are nucleated

what is the pcv like in reptiles

§PCV 20-40% in most species

• probs due to lifespan

erythrocyte lifespan in reptiles

Erythrocyte life span up to 800d in some species

why do you need to care when blood sampling reptiles (or of know blood has been lost)

May take 4 months for losses to be replenished

what is Polychromasia and reticulocytosis like in reptiles

Polychromasia and reticulocytosis low (<1%)

describe heterophils in reptiles

Predominant cell type

Equivalent to mammalian neutrophils

Intracytoplasmic fusiform granules

Increase in summer, decrease during hibernation

what happens to hetrophils in infection, inflam and stress in reptiles

Heterophilia

what happens to heterophils in chronic stress/ disease, severe infection

Heteropaenia

• probs due to slow replenishment

‘Toxic’ heterophils in severe inflammation

features of reptile lymphocytes

Morphology very similar to mammals

Lymphocytes generally lowest in winter

what can cause Lymphopaenia ( low)

malnutrition, stress immunosuppression and poor husbandry

what can cause lymphocytosis (high)

= inflammation, parasitic and viral disease, wound healing, ecdysis

features of reptile eosinophils

Eosinophils generally lower in summer

Eosinophilia = parasites and inflammation

features of reptile basophils

Basophils minimal seasonal change

Basophilia = parasitic and viral disease

what is azurophil in reptiles

Unique to reptiles

Like monocytes in mammals (but still have mono too)

Red-purple cytoplasm

More common in snakes

reptile

monocyte

what happens in reptiles to monocytes and azurophils in inflam and granulomatous disease

Monocytosis & Azurophilia