TECHNIQUE

Blood Sampling Rabbits (Disease Investigation & Management - Treatment and Care)

Sternal recumbency over the edge of a table for jugular access. Click here for full page view with caption. Sternal recumbency over the edge of a table for jugular access. Click here for full page view with caption. Dorsal recumbency for jugular access. Click here for full page view with caption. JB011_CentralArtery.jpg (24788 bytes)

Summary Information
Type of technique Health & Management / Disease Investigation & Management / Techniques:
Synonyms and Keywords
  • Venepuncture
  • Arterial blood collection
Description Note: Techniques used in wild lagomorphs
  • While most veterinary procedures described for use in domestic rabbits can also be used in wild lagomorphs, it is much more likely that sedation or anaesthesia will be required to carry out such procedures in these animals.

Various sites can be used for blood sampling in rabbits. Details of the advantages and disadvantages of each site and details which vary between sites (e.g. positioning the rabbit) are indicated below. 

  • Use of a sedative which produces vasodilatation (e.g. Fentanyl/fluanisone (Hypnorm, Janssen)) makes blood sampling easier. (B600.5.w5, B601.16.w16, J15.30.w2) or acepromazine 0.5 mg/kg plus butorphanol 0.5 mg/kg intramuscularly. (B284.10.w10)
    • Sedation with vasodilatation is particularly useful for blood sampling wild lagomorphs. (B284.10.w10)
General blood sampling
  • Choose a venepuncture site (see below)
    • Choose a venepuncture site where the skin is clean and has no obvious inflammation or infection. (B601.2.w2)
    • See the details of the various blood sampling sites listed below.
  • Prepare the venepuncture site
    • Shave or clip the skin over the venepuncture site. (B601.2.w2)
    • Consider applying EMLA cream.
      • EMLA cream is a local anaesthetic cream that contains lidocaine (lignocaine) and prilocaine and can produce full thickness skin anaesthesia. (B600.3.w3)
      • It has been recommended for use on the marginal ear vein venepuncture site (B600.3.w3, B601.2.w2) and the lateral saphenous site. (B601.2.w2)
      • Apply over the site 45 to 60 minutes prior to venepuncture and cover with a dressing or Clingfilm. (B600.3.w3)
    • Wipe the site with 70% isopropyl alcohol. (B601.2.w2)
    • Alcohol can be used to part the fur if shaving is not possible. (J213.9.w1)
  • Raise the vein
    • Raising the vein involves applying pressure to the vein to occlude the venous return therefore making the vein fill with blood. This may be performed by the person taking the blood sample or by an assistant depending on the venepuncture site and technique used.
  • Insert the needle
    • Insert the needle (bevel upwards) into the vein slowly and at a very acute angle, almost parallel to the skin.
  • Collect blood
    • Slowly fill the syringe with blood by gently pulling back on the syringe plunger. Be careful not to use too great a pressure on the syringe plunger because this may cause the vein to collapse and thus stops the blood flow. Too great a pressure may also damage the blood cells especially when using a small gauge needle.
    • Rotating the needle around its long axis so the bevel faces sideways or downwards may improve blood flow if the vein appears collapsed. (V.w125)
  • Stop raising the vein
    • Release the pressure and stop raising the vein when enough blood has been taken. 
  • Gently remove the needle from the vein
  • Apply pressure over the venepuncture site
    • Gently apply pressure with a small piece of cotton wool until clotting has occurred. This will help prevent the formation of a haematoma.
    • Ideally this is performed by the assistant so that the person taking the blood sample can perform the next step.
  • Immediately transfer the blood from the syringe to the appropriate blood tubes
    • Remove the needle from the syringe (this reduces the likelihood of haemolysis) and put the tip into the top of a blood tube and depress the plunger.
    • Fill the tubes to the level indicated and then cap them. 
    • If the tubes contain preservatives or anti-coagulants then immediately invert (do not shake) tubes several times to ensure proper mixing.
    • Also place a drop of blood onto a microscope slide to make an air-dried smear. (V.w125)
  • Dispose of the used syringe and needle
    • The syringe needs to be disposed of in the appropriate clinical waste container and the needle needs to be put into a sharps container.
  • Clean the venepuncture site
    • Clean any excess blood from the area after clotting has been achieved.

Venepuncture sites
Jugular vein
  • Advantages
    • Vein of choice for the collection of large volumes of blood because of the large diameter of the vessel. (B600.3.w3, B601.2.w2, B606.3.w3, J213.9.w1)
    • A good quality blood sample of five to ten millilitres can be collected quickly from this vein without clotting or haemolysis. (B600.3.w3)
  • Disadvantages
    • Visualisation can be difficult in obese rabbits. (B600.3.w3, B601.2.w2, J213.9.w1)
    • Visualisation can be difficult in females with large dewlaps. (B601.2.w2, B602.14.w14, J213.9.w1) However, other authors feel that the dewlaps do not really pose a problem. (B600.3.w3)
    • Short nosed breeds, e.g. Netherland Dwarf, or rabbits with upper respiratory tract problems, can become distressed or even cyanosed when the head is extended back for this venepuncture. (B600.3.w3)
  • Restraint and positioning
    • Conscious sampling is only possible in very calm or ill rabbits. Sedation or anaesthesia is often necessary. (B601.2.w2, B602.14.w14)
    • If carrying out conscious sampling then ideally wrap the rabbit in a towel. (B600.3.w3)
    • Sternal recumbency technique
      • The rabbit needs to be in sternal recumbency at the edge of a table. (B601.2.w2, B602.14.w14, B615.6.w6, J72.49.w1)
      • Draw the forelimbs vertically (downwards) over the table edge. (B601.2.w2, B602.14.w14, B615.6.w6, J15.29.w2, J213.2.w3)
      • The assistant should stand behind the rabbit and extend the head upwards (avoiding overextension of the neck because this can flatten the vein and reduce the diameter of the trachea along its axis, causing respiratory distress). (B601.2.w2, J72.49.w1, J213.2.w3, J213.9.w1, V.w125)
        • Ensure the rabbit's rump and spine are supported under the handler's armpit. (J15.29.w2)
      • The assistant should turn the rabbit's head slightly away from the vein to be sampled. (B601.2.w2) An alternative opinion is that it is important that the head is held straight. (B600.3.w3)
      • If necessary, sedate the rabbit with 1 mg/kg diazepam. (J72.49.w1)
    • Dorsal recumbency technique
      • If the rabbit is under general anaesthesia then it may be possible to take the blood sample in lateral or dorsal recumbency. (B601.2.w2)
        • The assistant should place the rabbit in dorsal recumbency on a table with the head over the edge, grasping the body with one hand and drawing the front feet back towards the rear with the other. (B602.14.w14, B615.6.w6)
        • The phlebotomist should take the head of the rabbit with their free hand and gently tip it backwards so that the ventral neck region is exposed. (B602.14.w14)
      • A conscious rabbit may be wrapped in a towel and placed in dorsal recumbency, the head extended by the person taking the sample, and the sample taken with the needle travelling cranial to caudal. (J213.2.w3)
  • Preparation of the venepuncture site
    • Clip the fur over the jugular furrow. (B600.3.w3)
  • Raising the vein
    • Use a digit to raise the vein at the thoracic inlet. (B600.3.w3, B601.2.w2) The thumb can be used to raise the vein and push the dewlap ventrally at the same time to expose a suitable area of neck. (B602.14.w14)
Marginal ear vein
  • Advantages
    • Easily visualised (B600.3.w3, B601.2.w2)
    • Easily accessible (B600.3.w3, B601.2.w2)
    • Useful for blood sampling in large breeds or for collecting small volumes of blood. (B600.3.w3)
    • Can be used in rabbits that weigh 2 kg or more. (B615.6.w6)
  • Disadvantages
    • The veins are small and easily collapse. (J213.2.w3)
      • In some breeds the vessel can be too small for a proper blood sample. (B600.3.w3, B601.2.w2)
    • It is difficult to collect large volumes of blood. (B601.2.w2)
    • Thrombosis of the vein can occur with subsequent sloughing of the skin particularly in breeds with small ears. (B602.14.w14, B606.3.w3, J213.2.w3, J213.9.w1)
    • Haematoma and bruising can occur. (B602.14.w14, J213.9.w1)
  • Restraint and positioning
    • Conscious sampling is possible but this is significantly aided by applying topical EMLA cream to the venepuncture site 45 to 60 minutes beforehand. (B600.3.w3, B601.2.w2)
    • Sternal recumbency in a relaxed position. (B601.2.w2)
  • Raising the vein
    • Warm the pinna for a few minutes (e.g. in a warm hand or a warm cloth or using a warm water bottle) to help dilate the vessel and improve blood flow. (B601.2.w2, B602.14.w14, J213.2.w3)
    • The assistant should place pressure on the lateral margin of the ear at the base. (B601.2.w2)
  • In rabbits with small veins, let the blood drip from the needle hub and collect it in an appropriate collection tube because using a syringe or vacuum tube will often collapse the vein. Syringes or vacuum tubes can be used on animals with larger pinna. (B602.14.w14)
  • This site has been used for blood sampling of Lepus arcticus - Arctic hare: (J240.34.w1)
Lateral saphenous vein 
  • Advantages
    • Large and easily visible. (J213.2.w3)
    • An ideal site for blood sampling. (J213.9.w1)
    • The large diameter of the vessel allows quick and easy blood sampling particularly in large rabbits. (B601.2.w2)
    • The vessel is easily accessible as it runs diagonally (medial to lateral) across the lateral aspect of the tibia just proximal to the hock. (B602.14.w14, J213.9.w1)
  • Disadvantages
    • The vessel is often mobile. (B601.2.w2)
    • Collapses if excess negative pressure is applied. (J213.2.w3)
  • Restraint and positioning
    • Conscious sampling is usually possible and is aided by applying topical EMLA cream to the venepuncture site beforehand. (B601.2.w2)
    • A towel can be useful for restraint. (J213.9.w1)
    • Provide a visual barrier to help calm the patient, e.g. cover the rabbit's head with a towel. (B601.2.w2, J213.9.w1)
    • Place the rabbit in sternal recumbency ((B601.2.w2, J213.2.w3) along the edge of the table and gently hold one hind leg over the table edge. (B601.2.w2)
    • The phlebotomist should hold the tarsus and pull the skin taut to stabilise the vessel. (B601.2.w2)
    • OR the assistant holds the rabbit with its head between the assistant's body and elbow, body resting along the assistant's forearm, and leg to be sampled held by the hand to occlude venous return. (J213.2.w3)
  • Raising and visualising the vein
    • The assistant should apply pressure to the caudal stifle (B601.2.w2) at the crus of the stifle, occluding venous return. (J213.2.w3) or just above the hock joint (B602.14.w14). Alternatively pressure can be applied across the proximal thigh. (J213.9.w1)
    • A tourniquet may be considered. (B601.2.w2)
    • Wet the fur with alcohol or dilute chlorhexidine solution to improve visualisation. (J213.2.w3)
      • Plucking fur from over the vein improves visualisation. (V.w125)
Cephalic vein
  • Advantages
    • When the vein is easily visible, this is a good site for blood sampling. (B602.14.w14)
  • Disadvantages
    • The skin and fur on the medial foreleg is often contaminated with exudates from respiratory infection; it is important to ensure the site is properly aseptically prepared before blood is taken. (J72.49.w1)
    • The vessel is of a small diameter and often mobile. (B601.2.w2, J213.2.w3)
      • Use a small-gauge needle, 25 gauge or smaller, and a small-volume syringe (1 mL). (J213.2.w3)
    • The antebrachium of the rabbit is short and this limits the usefulness of this vessel particularly in small breeds. (B601.2.w2, B602.14.w14)
    • This site may be more stressful for a rabbit because the handler is working near to the head of the animal. (J213.9.w1)
    • If intravenous catheter placement is going to be part of the therapeutic plan then save these vessels for this purpose and choose an alternative site for venepuncture. (B602.14.w14, J213.9.w1, P113.2005.w2)
  • Restraint and positioning
    • Conscious sampling only possible in very calm or ill rabbits. Sedation or anaesthesia is often necessary. (B601.2.w2)
    • Place the rabbit in sternal recumbency and pull one forelimb towards you. (B601.2.w2)
    • The assistant needs to gently hold the head away from the extended limb. (B601.2.w2)
  • Raising the vein
    • The assistant should occlude the vessel at the elbow. (B601.2.w2)
    • Alternatively a tourniquet may be used. (B601.2.w2)

Arterial blood collection
Indications
  • Blood gas analysis. (B601.2.w2)
  • Measurement and monitoring the arterial blood pressure. (B601.2.w2, J213.9.w1)
  • Evaluation of the acid-base status. (B601.2.w2)
  • Note: arteries should NOT be used for administration of medication or routine blood collection. (B601.2.w2)
Sites
  • Femoral artery
    • General anaesthesia is necessary. (B601.2.w2)
  • Central auricular artery
    • Conscious sampling is possible but a local anaesthetic should be used, e.g. EMLA cream. (B601.2.w2)
    • Blood can be taken quickly from this vessel but if the artery is damaged then there is a small risk of permanent damage to the pinna's blood supply and subsequent sloughing of part of the ear. (B600.3.w3, B601.2.w2, B606.3.w3, J213.9.w1)
Technique
  • As for venepuncture but it is not necessary to "raise" the vessel. (B601.2.w2)
  • Ideally, an 'over-the-needle' catheter should be placed (technique as for intravenous catheterisation - see Intravenous Injection and Catheterisation of Rabbits), especially if serial samples are going to be taken. (B601.2.w2)
  • Firm pressure to the venepuncture site is essential for several minutes after the procedure to prevent haemorrhage and minimise haematoma formation. (B601.2.w2, B615.6.w6)
Appropriate Use (?)
  • Blood films:
    • In addition to placing the blood sample into the sample bottles, it is a good idea to make a fresh blood film. This film can be quickly stained and then the differential white cell count can be examined which, in addition to a PCV, provides an immediate assessment of the animal's health status if there is no access to sophisticated laboratory equipment. (B600.3.w3)

Note: Different blood sampling sites are appropriate for different individuals and purposes

  • Jugular vein
    • Vein of choice for the collection of large volumes of blood because of the large diameter of the vessel. (B600.3.w3, B601.2.w2, B606.3.w3, J213.1.w1, J213.9.w1)
    • A good quality blood sample of five to ten millilitres can be collected quickly from this vein without clotting or haemolysis. (B600.3.w3)
  • Marginal ear vein
    • Easily visualised and easily accessible (B600.3.w3, B601.2.w2)
    • Useful for blood sampling in large breeds or for collecting small volumes of blood. (B600.3.w3)
    • Can be used in rabbits that weight 2 kg or more. (B615.6.w6)
  • Lateral saphenous vein
    • An ideal site for blood sampling. (J213.9.w1)
    • The large diameter of the vessel allows quick and easy blood sampling particularly in large rabbits. (B601.2.w2)
    • The vessel is easily accessible as it runs diagonally (medial to lateral) across the lateral aspect of the tibia just proximal to the hock. (B602.14.w14, J213.9.w1)
  • Cephalic vein
    • When the vein is easily visible, this is a good site for blood sampling. (B602.14.w14)
  • Arterial blood collection:
    • Blood gas analysis. (B601.2.w2)
    • Measurement and monitoring the arterial blood pressure. (B601.2.w2)
    • Evaluation of the acid-base status. (B601.2.w2)
    • Note: arteries should NOT be used for administration of medication or routine blood collection. (B601.2.w2)
Controversial method of blood sampling
Cardiocentesis
  • Laboratory rabbits are occasionally bled for large blood samples by cardiocentesis but this is not recommended procedure in pet rabbits due to the inherent risks (myocardial damage, cardiac tamponade, and death (B602.14.w14)). (B600.3.w3, B601.2.w2)
Notes
  • Total blood volume is 57 - 78 mL/kg. (J213.2.w3)
  • Remove no more blood (volume in mL) than 1% of the rabbit's body weight in grams. (J213.1.w1)
  • When a limited amount of blood is available, tests should be chosen prioritized according to the suspected differential diagnoses. (J213.1.w1)
  • Lighting
    • The veins of rabbits are generally quite small therefore adequate lighting is necessary for good visualisation. (B601.2.w2)
  • Sterile equipment
    • Needles, butterfly infusion sets, or intravenous catheters must remain sterile; only handle them at the hub. (B601.2.w2)
  • Blood sample for a coagulation profile
    • It is necessary to penetrate the vessel on the first attempt for a valid sample. (B601.2.w2)
  • Blood sample for a bacterial culture
    • It is necessary to aseptically prepare the skin and sterile gloves must be worn. (B601.2.w2)
Complications/ Limitations / Risk
  • In wild lagomorphs
    • While most veterinary procedures described for use in domestic rabbits can also be used in wild lagomorphs, it is much more likely that sedation will be required to carry out such procedures in wild lagomorphs.
  • Clipping
    • Take care not to damage the delicate skin during clipping or plucking. (J213.9.w1)
  • Preventing the patient suddenly jumping during venepuncture
  • Maximum volume of blood that can be taken
    • The circulating blood volume of a rabbit is around 55 to 78 ml/kg bodyweight. (B601.2.w2, B604.3.w3) and
      •  up to 10 % of this total can be safely removed (B601.2.w2) every three to four weeks; (B604.3.w3)
      • or 1% of this total can be removed every day. The haematocrit should be monitored and a pause in the blood collection may be necessary if the PCV falls below 35 %. NB. the PCV may not reduce for several days after the bleeding. (B604.3.w3)
    • "As a rough guide it is safe to take up to 1% of the animal's bodyweight of blood". (B600.3.w3)
  • Prevention of a haematoma
    • Venepuncture: gentle digital pressure (or a brief pressure wrap) over the site of venepuncture is necessary after the needle is removed to prevent the formation of a haematoma. (B601.2.w2, J213.9.w1)
    • Arterial sampling: firm pressure to the venepuncture site is essential for several minutes after the procedure to prevent haemorrhage and minimise haematoma formation. (B601.2.w2, B615.6.w6)
  • Haemolysis or clotting of the sample
    • Rabbit blood will quickly clot and so needs to be collected rapidly but avoiding haemolysis; it can be advantageous to heparinise the syringe and needle prior to use. (B600.3.w3)

Note: Different blood sampling sites have different limitations for their use.

  • Arteries
    • Arteries should NOT be used for administration of medication or routine blood collection. (B601.2.w2)
    • Femoral artery
      • General anaesthesia is necessary. (B601.2.w2)
    • Central auricular artery
      • Conscious sampling is possible but a local anaesthetic should be used, e.g. EMLA cream. (B601.2.w2)
      • Blood can be taken quickly from this vessel but if the artery is damaged then there is a small risk of permanent damage to the pinna's blood supply and subsequent sloughing of part of the ear. (B600.3.w3, B601.2.w2, B606.3.w3, J213.9.w1)
  • Jugular vein
    • Visualisation can be difficult in obese rabbits. (B600.3.w3, B601.2.w2, J213.9.w1)
    • Visualisation can be difficult in females with large dewlaps. (B601.2.w2, B602.14.w14, J213.9.w1) However, other authors feel that the dewlaps do not really pose a problem. (B600.3.w3)
    • Short nosed breeds, e.g. Netherland Dwarf, or rabbits with upper respiratory tract problems, can become distressed or even cyanosed when the head is extended back for this venepuncture. (B600.3.w3)
  • Marginal ear vein
    • In some breeds the vessel can be too small for a proper blood sample. (B600.3.w3, B601.2.w2)
    • It is difficult to collect large volumes of blood. (B601.2.w2)
    • Thrombosis of the vein can occur with subsequent sloughing of the skin particularly in breeds with small ears. (B602.14.w14, B606.3.w3, J213.9.w1)
    • Haematoma and bruising can occur. (B602.14.w14, J213.9.w1)
  • Lateral saphenous vein
    • The vessel is often mobile. (B601.2.w2)
  • Cephalic vein
    • The vessel is of a small diameter and often mobile. (B601.2.w2)
    • The antebrachium of the rabbit is short and this limits the usefulness of this vessel particularly in small breeds. (B601.2.w2, B602.14.w14)
    • This site may be more stressful for a rabbit because the handler is working near to the head of the animal. (J213.9.w1)
    • If intravenous catheter placement is going to be part of the therapeutic plan then save these vessels for this purpose and choose an alternative site for venepuncture. (B602.14.w14, J213.9.w1)
Equipment / Chemicals required and Suppliers
  • Appropriate-sized sterile needle and syringe.
    • Use a small 25 or 27 gauge needle. (B602.14.w14)
    • Use a 20 to 23 gauge needle. (B604.3.w3)
    • 24 gauge or smaller. (B615.6.w6)
  • Appropriate anticoagulant sample tubes.
    • Lithium heparin tubes are useful for small volumes, in order to maximise the volume of plasma. (J213.1.w1)
  • Glass slide for making a blood smear.
  • EMLA cream.
Expertise level / Ease of Use
  • This procedure should only be carried out by an individual with appropriate clinical training and practical experience.
Cost / Availability
  • Equipment used for venepuncture is relatively inexpensive.
  • Cost of external laboratory work.
  • Cost of reagents and equipment for in-house testing.
Legal and Ethical Considerations
  • Dirty needles and syringes must be disposed of properly (needles always into a properly marked sharps container and syringes into a clinical waste container). (D249.w10)
  • In some countries there may be legislation restricting the use of this type of technique to licensed veterinarians. For example in the UK: "The Veterinary Surgeons Act 1966 (Section 19) provides, subject to a number of exceptions, that only registered members of the Royal College of Veterinary Surgeons may practice veterinary surgery." (see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Treatment of Animals by Non-Veterinary Surgeons).).
Author Nikki Fox BVSc MRCVS (V.w103)
Referee Debra Bourne MA VetMB PhD MRCVS (V.w5); Molly Varga BVetMed DZooMed MRCVS (V.w125)
References B600.3.w3, B601.2.w2, B602.14.w14, B604.3.w3, B606.3.w3, B615.6.w6, J72.49.w1, J213.1.w1, J213.2.w3, J213.9.w1, J240.34.w1, P113.2005.w2

Return to Top of Page