This task is best considered in 3 steps:

1. Induction.
2. Maintenance.
3. Ancillary equipment.

Whilst most of the instruments and apparatus need not be sterile; they must be clean and well maintained. Remember however, that sterility is essential for intravenous catheterisation and therefore the site for venipuncture (usually the cephalic vein) is to be prepared as for surgery. Intravenous catheters MUST be sterile to reduce the risks of infection and thrombophlebitis (inflammation of a vein). Clean the preparation surface with disinfectant (such as a peroxide - Virkon or a halogenated tertiary amine hydrochloride - Trigene), dry the surface and lay down a clean paper or cotton drape upon which the smaller items of equipment are to be placed. The necessary equipment is listed below along with the uses for each:

1. Clippers or clean curved scissors - to clip the hair from the venipuncture site (usually the cephalic vein). A pair of scissors should also be available to cut lengths of tape and bandage (this blunts them so do not use the same pair as those used for clipping hair!).
2. Antiseptic solution - to clean the site prior to venipuncture. This should be contained within a suitable receptacle such as a medium-sized kidney dish. Chlorhexidine (Hibiscrub) or povidone iodine (Pevidine) are suitable.
3. Lint free swabs or cotton wool - to apply the antiseptic solution. Cotton wool may leave fibres, so swabs are preferable.
4. 70% Alcohol solution such as Industrial Methylated Spirit - applied to the skin following the antiseptic solution to provide residual bactericidal activity. Contamination is best avoided by direct application from a plastic bottle.
   Note: Care not to soak tiny patients due to heat loss on evaporation of alcohol solution.
   
5. Sterile catheter - inserted into the vein to allow administration of the induction agent. It should be of a suitable gauge for the patient. An over-the-needle catheter or butterfly scalp vein set are ideal, but a normal injection needle can be utilised. A scalpel blade (size 10 or 15) is necessary to expose the vein if a scalp set is used.
   
   

   Catheter Size Patient Suitability 24-22 guage Cats and small dogs 22-20 guage Medium dogs 20-18 guage Large dogs

6. Sterile syringe loaded with the induction agent - the amount prepared should be of a suitable quantity for the patient. Accurate dose rates are essential. Agents such as Thio-pentone must be reconstituted before use at the correct percentage solution. Remember that a 5% solution contains 5g of anaesthetic agent in 100mls, while a 2.5% solution contains 2.5g of anaesthetic agent in 100mls. Further information may be found in Book 1 - Pharmacy and Dispensing. When using glass vials, dispose of the snap-tops carefully in the sharps container, and always seal up the vial and refrigerate if necessary after use.
7. Adhesive tape strips - to hold the syringe in place or tape in the catheter. Micropore is ideal due to its transparency which allows visualisation of the syringe gauge beneath it. Also, it is not as adhesive as Elastoplast which tends to pull out the patient's hair when removed unless spirit is used to dissolve the glue. Zinc tape or Elastoplast however is preferable for securing a catheter since it is stronger.
8. Rubber stopper or three way tap - to seal the catheter. It is beneficial for the catheter to remain in place throughout the anaesthetic since a patent intravenous route is readily available for the administration of emergency drugs and or fluids. Rubber stoppers are preferable to plastic since drugs can be administered directly without their removal. Heparin should be available in case of a blockage at 4 units per ml dilution in saline (1:1000 Heparin).
9. Sterile water - for injection into the venipuncture site in the event of extravasation (accidental injection outside of the vein). Drugs such as Thio-pentone are extremely irritant and can cause severe skin sloughing if extravasation occurs, and therefore must be diluted immediately.
10. Endotracheal tube and connector - these connect the patient to the anaesthetic circuit. The endotracheal tube is passed through the larynx and glottis to the trachea and maintains a patent airway. The connector attaches the proximal end of the tube to the circuit. Dirty or cracked tubes must never be used. A wide range of sizes are available but as a general guide; a tube of 3-4mm in diameter is usually suitable for cats, while a tube of 8-9mm in diameter should be appropriate for a 20kg dog.
11. Cuff inflator - to enable inflation of the cuff at the distal end of the endotracheal tube. Cuffed tubes are considered superior since they provide an airtight seal within the trachea. Inflation prior to use ensures that tubes with damaged cuffs are not used. Care on inflation of cuff needs to be taken as over inflation can result in tracheal damage.
12. Bandage strips - to secure the proximal end of the endotracheal tube in place. Open weave bandage of 2.5cm width is suitable. A length is tied around the tube, then secured caudally between the ears or over the muzzle depending upon head shape.
13. Water-soluble lubricant gel - enables ease of placement of the endotracheal tube and may contain local anaesthetic which also facilitates the procedure. Xylocaine gel and Lignocaine spray may be used.
14. Oesophageal stethoscope - used to monitor the patient's heart during anaesthesia.
15. Rectal thermometer and lubricant - used to monitor the patient's temperature during anaesthesia. Remember that general anaesthesia causes a decrease in body temperature and that is therefore vital to keep the patient dry and warm.
16. Other items -
    1. Heat pad.
    2. Emergency kit.
    3. Pulseoximeter.
    4. ECG machine.
    These items are generally too large to lay out for use in the practical examination, but are very important and therefore should never be overlooked in practice.
    
    Finally, small animal anaesthesia should never be performed without access to an anaesthetic machine and suitable circuit. Even if a patient is only to undergo minor surgery where gaseous maintenance is not considered necessary, a patent airway and immediate access to oxygen could prevent a fatality should a problem arise.

Anaesthetic machine - for the maintenance of anaesthesia with volatile agents. Ensure that sufficient gas is available and that the vaporiser is full. A spanner and spare washers should be to hand and an efficient scavenge system is essential.

Anaesthetic circuit - for the delivery of volatile gases from the machine to the patient and the removal of carbon dioxide. The circuit should be of a suitable size and type for the patient. If a reservoir bag is used, this must be checked prior to use for leaks. Soda lime canisters must be checked and replenished if necessary.