Exotics Flashcards
List the blood sampling sites for lizards
- Ventral coccygeal vein
- Jugular vein
- Ventral abdominal vein
Describe the method for sampling blood from the ventral coccygeal vein of a lizard
- Entry 1/3rd down the tail to avoid hemipenes and anal glands
- Can go ventral or lateral
- Ventral: needle at 30-40° angle to tail, keep going until hit blood or bone, if hit bone pull needle back and try again
- Lateral: palpate lateral processes and direct needle just underneath and aim towards midline
Describe the method for blood sampling from the jugular vein of lizards
- Blind approach along imaginary line from dorsal ear to shoulder
- Transillumination can be used to highlight veins in sedated animals
- Often quite superficial
What are the main advantages of sampling blood from the jugular in lizards?
- Useful in large, longer neck species
- Jugular least likely to get lymph contamination
Discuss the use of the ventral abdominal vein for blood sampling in lizards
- May be visualised in some species
- Difficult to prevent haematomas
- Not often used
- Risk of liver damage
List the sites for blood sampling in snakes
- Ventral coccygeal vein
- Palatine veins
- Heart
Discuss the value of the ventral coccygeal vein for sampling blood in snakes
- In most species presented with, is not distinct, may get blood but is not the vein
- In venomous species coccygeal is well developed, but rarely see these
Outline the disadvantages of using the palatine veins for blood sampling in snakes
- Prone to haematoma formation
- Large, anaesthetised snakes only
- May exacerbate anorexia
- Risk of striking if not anaesthetised
Describe the method for blood sampling from the heart in snakes
- Dorsal recumbency
- Heart located visually, with doppler or ultrasound
- Stabilise heart between thumb and finger
- Needle entry ventral midline at 30° angle in cranial direction aiming for caudal point of ventricle
- May get some blood, then stops due to contraction of heart in systole, in diastole will get blood again
Describe the advantages of blood sampling from the heart in snakes
- Virtually no damage if done correctly
- Heart muscle seals over entry wound
- Can be conscious
List the blood sampling sites in chelonia
- Jugular
- Subcarapacial
- Dorsal coccygeal vein
Describe blood sampling from the jugular vein in chelonia
- Along line from dorsal ear scale to shoulder
- Tends to be superficial and visible in some species
- Preferred route in chelonia, lowest risk of lymph contamination
- Easier in weak tortoise
What are the main risks of jugular sampling in chelonia?
- Not enough pressure on neck afterwards for a few mines can lead to very large haematoma
- Restraint can be difficult and stressful
Describe blood sampling from the sub-carapacial vein in chelonia
- Entry point craniodorsal midline where skin joins carapace
- Aim for point a junction of 1st and 2nd vertebral scute on midline
- May need to bend needle slightly
- Head may be retracted or extended
What are the main advantages of using the sub-carapacial vein for sampling in chelonia?
Good for species that may bite or won’t allow access to head
Describe the problems associated with sub-carapacial vein in chelonia for sampling and injection
- If too far cranial may sample lymph
- When head is retracted, cervical spine bends and risk pithing terrapin as go through spinal cord between the vertebrae
- Used as induction area, spinal cord can become acutely paralysed. Some recover after weeks, others don’t
Describe blood sampling from the dorsal coccygeal vein in chelonia
- Often superficial
- Aim as far cranial as possible
- Often lymph contaminated
- Better for induction rather than diagnostics
- Angle needle on midline, advance to either bone or blood
List the sites for blood sampling in the rabbit
- Marginal ear vein (first option)
- Jugular vein (second option)
- Central ear artery
- Cephalic and saphenous
Describe the method for sampling from the marginal ear vein
- Small (25G) needle and 1ml syringe
- Wrap in towel
What are the main risks associated with blood sampling from the ear in rabbits?
- Pinnal necrosis with poor/rough technique
- Irritating drugs, catheters and bandages can also cause pinnal necrosis
Compare blood sampling from the marginal ear vein and from the central ear artery in the rabbit
- Similar techniques
- In artery, blood pressure fills syringe, no negative pressure needed
Outline the disadvantages of using the jugular vein for blood sampling in the rabbit
- Dewlap can get in the way (esp. females)
- Poor/rough technique can cause blindness in ipsilateral eye
- Restraint may inhibit respiration
Outline the disadvantages of using the cephalic or saphenous for blood sampling in the rabbit
Can be easier for rabbit to kick out which disrupts sampling and can cause injury, proper restraint required
Describe blood sampling from the cephalic vein in guinea pigs
- More lateral vs rabbit
- Thick skin
- For catheter, first insert hypodermic needle then pass catheter through this
What is the most useful sampling site for large volumes of blood in small exotic mammals? (G-pig, rat, mouse, gerbil, hamser)
- Cranial vena cava
- In all but guinea pig, saphenous good too
List the blood sampling sites for rats, mice, gerbils and hamsters
- Lateral tail vein
- ventral tail artery
- Lateral saphenous vein or cranial vena cava
Compare the position of the jugular vein in cats and ferrets
Jugular more lateral in ferret than cat
Which site is best for blood sampling of uncommon exotic mammals?
Femoral vein, cranial vena cava also good
Outline the method for sampling blood from the femoral vein in uncommon exotic mammals
- Most require sedation or GA
- Place in lateral recumbency with leg to be sampled on table
- Apply pressure in proximal inguinal canal with index finger of free hand, palpate femoral pulse
- Direct needle slightly caudal to it in line with femur
- Keep slight negative pressure on syringe until flash of blood in hub
What are the most concerning complications that can occur as a result of blood sampling from the cranial vena cava?
- Pericardial effusion
- Cardiac tampenade
- Death
- In some species, e.g. guinea pig, heart lies very close to sample site
Describe the method for blood sampling from the cranial vena cava
- Thoracic radiograph first to assess any potential effects of pathology on anatomy
- Anaesthetised
- Dorsal recumbency, head extended, forelimbs retracted caudally
- 26G, 12mm needle or smaller
- Advanced from notch where first rib meets manubrium towards contralateral hindlimb
- Approximate 30° angle until blood flash
Explain the effect of anaesthesia on the blood sample of a ferret, and how this can be avoided
Will lower PCV - sample asap after sedation/induction to minimise splenic sequestration effect
What does a blue/purple tinge to the background of a reptile blood smear suggest?
Lymph is present - need to sample again
What is a species specific blood sampling problem with some species of reptiles, especially Geckos, regarding blood sampling from the tail and how can this be avoided?
Tail autotomy (dropping tail) in response to sampling. Avoid with GA or avoid using tail
Explain the safe volume of blood that may be taken from a reptile
- Circulating blood vol approx 5-8% of body weight
- May collect up to 10% of this i.e. 5-8ml/kg
- Generally use 1ml/kg
- Generally don’t need more than 2ml
What amount of blood can be taken from an ill reptile?
Half the normal amount i.e. 0.5ml/kg
Explain the safe volume of blood that may be taken from a rabbit
- Circulatory vol ~55-70ml/kg
- Can collect up to 10% i.e. 5.5-7ml/kg
- Rarely need more than 2ml
Explain the safe volume that can be taken from guinea pigs, rats, mice, gerbils, hamsters and ferrets
- G pig: blood vol 70-75ml/kg, 0.1-0.2ml can be taken
- Rat, mouse, gerbil, hamster: blood vol 60-70mg/kg, collect 10%
- Ferret: blood vol 50-70ml/kg, collect 10%
Outline the typical haematology and biochemistry preparation for reptiles
- EDTA tends to hamolyse reptile blood cells, Li-heparin anicoag of choice
- Make 2 good smears
- Haematology usually manual
Why is thorough skin preparation prior to blood sampling required for reptiles?
Ski heavily contaminated: pseudomonas, salmonella, klebsiella, e coli, fungi common
Why is reptile haematology typically carried out manually?
Automated techniques confused by nucleated red blood cells
Outline the typical haematology and biochemistry preparations for rabbits
- Clots quickly
- EDTA for haematology
- Li-heparin for routine biochem
- Fluoride oxalate for glusose
- 2 fresh blood smears
Describe the normal rabbit erythrocytes
Anisocytosis and polychromasia common, normal due to shorter RBC life span
Describe the appearance of rabbit neutrophils/heterophils
- Granular cytoplasm, easily mistaken for eosinophils
Describe the typical white blood cells of rabbits
- Neutrophils more granular
- Basophils present commonly
- Lymphocytes, eosinophils, monocytes similar to dog/cat
- Neutrophil to lymphocyte ratio 1:1, (45%:45%) of blood, rest is basophils, monocytes etc.
Describe the effect of stress or disease on total white cell count in the rabbit
- Rarely increases
- Instead, neutrophil:lymphocyte ratio changes
What is indicated by a relative neutrophilia and lymphopaenia in a rabbit?
Infection or chronic stress
What is indicated by a relative lymphocytosis in a rabbit?
Acute stress (caused by adrenaline)
What are Kurloff cells?
Cells in guinea pigs produced by thymus under oestrogen stimulation, resembles lymphocyte with round to oval inclusions
What is the most abundant cell type in guinea pig haematology?
Neutrophil
Describe the appearance of ferret neutrophils
Contains small, pale red granules
Describe the appearance of ferret eosinophils
Granules rounded and bright red
Describe the normal haematology of ferrets
- Higher HCT, Hb and RBC counts
- White cell count generally low (3-4x10^9)
- Ferrets appear to have no blood groups
Describe the erythrocytes and thrombocytes of reptiles
- Both nucleated
- Similar function to mammals
- Erythrocyte life span up to 800d in some species
- Polychromasia and reticulocytosis very low (<1%) generally monomorphic population of erythrocytes
- May take 4 months for losses to be replenished
- Erythrocytes greyer cytoplasm, pinker nucleus
Describe the haematocrit in reptiles
PCV 20-40%, lower in reptiles vs mammals, atheltic species e.g. monitors may have higher
What is the effect of serial sampling in reptiles?
Haematocrit will decrease due to long time to replenish erythrocytes
Describe the heterophils of reptiles
- Equivalent to mammalian neutrophils
- Predominant cell type
- Have fusiform intracytoplasmic granules
- May get toxic change of granules/nuclei in response to severe inflammation
- Some species variation in morphology of the granules
Describe the seasonal of reptilian heterophilss
- Increase in summer
- Decrease during hibernation
What is indicated by heterophilia in reptiles?
Infection, inflammation, stress
What is indicated by heeropaenia in reptiles?
Chronic stress/disease, severe infection
What is the significance of finding heeropaenia in a tortoise in summer?
- Should be at peak levels of heterophils
- Has been suffering so long that has missed this
- Low level compromise for long periods
What does toxic change of reptilian heterophils indicate?
Being produced too quickly or damaged by infection - starting to struggle with infection
What is indicated by finding heterophilia with toxic change in a reptile?
Bad infection, but is fighting it
Describe the appearance of reptilian lymphocytes
Morphology very similar to mammals
Describe the seasonality of reptilian lymphocytes
Generally lowest in winter
What does lymphopaenia in reptiles indicate?
Malnutrition, stress, immunosuppression and poor husbandry
What does lymphocytosis in reptiles indicate?
Inflammation, parasitic and viral disease, wound healing, ecdysis
Describe the appearance of eosinophils and basophils of reptiles
Similar morphology to mammalian
Describe the seasonality of reptilian eosinophils and basophils
- Eosino: lower in summer
- Baso: minimal seaosnal change
What is indicated by eosinophilia in reptiles?
Parasites and inflammation
What is indicated by basophilia in reptiles?
Parasitic and viral disease
Describe azurophils in reptiles
- Unique to reptiles
- Similar to monocytes
- red-purple cytoplasm
- More common in snakes
- Commonly mistaken for activated lymphocyte
Describe the monocytes of reptiles
Similar to those of mammals, biggest cells on smear
What is indicated by monocytosis and azurophilia in reptiles?
- Inflammation and granulomatous disease, rare in healthy
- E.g. osteomyelitis, TB often leads to raised monocytes
- Tend to respond to the same type of disease
Briefly outline the developement of T cells in birds
T lymphocyte precursors produced by stem cells in the embryonic yolk sac and bone marrow, then develop into T lymphocytes in the thymus
Describe the Bursa of Fabriciu
- Unique to birds
- Dorsal diverticulum in the proctodeum
- Consists of fold of lymphoid tissue
- Maturation of B cells
Describe the spleen of birds
- Right side of coelom between proventriculus and ventriculus
- Shape varies: triangular in ducks, geese, elongated in budge, oval in pigoens and chickens, round in parrots,
- Not a blood reservoir therefore small
- Phagocytoses aged erytrhocytes
- Aids in lymphopoeisis and production of antibody
- Purely immunological
Outline the restraint of birds for blood sampling
- Sedation/GA with iso less risk than physical in sick or fractious birds
- GA may reduce haematoma formation
- Towels, not gauntlets
- Prolonged restraint can lead to stress and hyperthermia
List the blood sampling sites for birds
- Jugular vein
- Cutaneous ulnar/basilic vein
- Medial metatarsal vein
- Toe nail clip
- Venous occipital sinus
- Bone marrow aspirate
Describe blood sampling from the jugular vein in birds
- Large, accessible
- Right jugular larger
- Easily visualised in most species without plucking feathers (apteria)
- Palpation and blind technique in some
- can be difficult to prevent/stop haematoma
- Single handed restrain in small birds
- Advance needle cranial-caudal or caudal-cranial using 1st finger or thumb respectively as support for syringe
Why is care required in pigeons for blood sampling from the jugular vein?
Have capillary bed network around neck, needle may cause significant haematoma
Describe blood sampling from the cutaneous ulnar/basilic vein in birds
- Good for small samples/larger birds
- Potential to fracture wing in conscious birds esp. aged females
- Haemtomas common and can be severe
- Place in dorsal recumbency with wing extended, stabilise with thumb and forefinger
- Basilic crosses extensor tendon
In which species is blood sampling from the medial metatarsal vein particularly useful?
Chickens and waterfowl
Describe blood sampling from the medial metatarsal vein in chickens
- Laid in lateral recumbency without sedation
- Vein accessible
- Base of first digit, groove between tendons
- Vein either proud of groove or may sink into groove if dehydrated
Describe the method for blood sampling from the medial metatarsal vein in birds
- Sternal recumbencywith limbs extended caudally, or restrained in towel with feet and ventrum facing sampler
- Limb held by assistant
- Light pressure bandage easily placed to prevent haematoma
Describe the use of a toe nail clip in birds for blood sample
- Painful
- Artefacts common in cell morphology and may alter some biochemistries
- Not recommended and does not give diagnostic sample
Discuss the use of the venous occipital sinus for blood sampling in birds
- Described in waterfowl
- Rarely used in practice
- Usually used in the field
- Risk of pithing the bird
- May be useful in some circumstances e.g. euthanasia
When are bone marrow aspirates generally used for blood sampling in birds?
Investigation of anaemia or sample for Psittacine Beak and Feather disease PCR
Describe the method for bone marrow aspirates in bids
- Proximal tibiotarsus
- GA and post-sampling analgesia required
- 2.5ml syringe and 23G needle for average sized parrot
- Entry medial aspect tibial plateau avoiding patellar ligament
- Hypodermic needle ok, may need to use needle first to make hole then aspirate bone marrow through a second needle
Outline some risk factors assocaited with blood sampling in birds
- Veins fragile and prone to haematomas
- Haematomas can be life threatening
- Haematomas generally due to poor handling but can get clotting defects due to liver disease, diet (e.g. seed diet)
- Post-sampling haemorrhage and haeomtoma formation
- Tight restraint can kill
Explain the volume of blood that can be taken from birds
Circulating vol @6-12% of bodyweight in healthy animal
- May collect up to 10% of this i.e. 6-12ml/kg
- If in poor health take much less
- In small bird need to prioritise tests as have little blood available
Describe the preparation of avian biochem and haematology
- EDTA tends to haemolyse RBCs in some species
- Li-heparin for haematology and biochem in small patients
- 2 good smears
- Haematology usually manual due to nucleated red blood cells
Describe the erythrocytes of birds
- Nucleated
- Short life span 25-45 days
- Cell size varies with species: larger in ratites, smaller in passerine
- Mild polychromasia and anisocytosis normal
- Smaller cells better for flight
Describe the PCV in birds
35-55%, higher than reptiles and some mammals
Outline the recovery feom anaemia in birds
Rapid (3-4 days), RBCs have short life span, rapid cell regeneration with appropriate treatment
Describe thrombocytes of birds
- analogous to mammalian platelets
- Originate from stem cell not megakaryocytes
- Nucleated
- Phagocytic functions
- Clotting function weaker vs mammals (less thromboplastin)
What do raised thrombocytes in birds indicate?
Infection (have some phagocytic function)
Describe the heterophils of birds
- Similar function to mammalian neutrophil
- Most abundant cell in most species
- Round with lobed basophilic nucelus and prominent eosinophilic needle-shaped, oval or round cytoplasmic granules
- Cytoplasm colourless
- Phagocytosis, bacteriocidal, role in acute inflammation
What do the following indicate in a bird?
a: heterophilia
b: heteropaenia
a: heterophilia = stress, infection
b: heteropaenia = acute or severe inflammation, sepsis, viruses
Describe the eosinophils of birds
- Normally present in low numbers
- Function uncertain, may be involved in parasitic infection similar to mammals
- Round cells, lobed basophilic nucleus
- Cytoplasm stains clear
- Granules brightly eosinophilic tend to be round
- With rapid stains can be hard to differentiated from neutrophils
