INTRODUCTION
The main indications for fluid therapy are:

• Replacement of dehydration deficits
• Maintenance of normal hydration
• Replacement of essential electrolytes and nutrients
• To act as a carrier for certain intravenous drugs

Dehydration often goes hand in hand with shock, and it is therefore essential to replace deficits as soon as possible. In any case where dehydration is suspected, always ask the client to bring the animal to the surgery immediately. Having informed the veterinary surgeon, gather together the necessary equipment so that no time is lost in preparation.

EQUIPMENT

1. Make sure that an assistant is on hand to hold the patient.
2. Prepare equipment for venous access; this comprises:
   • SCISSORS or CLIPPERS - to remove hair from the site of the vein (usually the cephalic); this allows better visualisation and sterility.
     Note: Some animals are frightened of the noise made by electric clippers; if the animal is of a nervous disposition it may be better to use scissors.
   • DILUTE SKIN ANTISEPTIC (such as povidone iodine Pevidine or chlorhexidine Hibiscrub) - for cleaning the area.
   • METHYLATED SPIRIT - for application following skin antiseptic; it is vital to prevent introduction of infection.
   • SURGICAL COTTON WOOL OR SWABS - to apply the antiseptic and spirit; prepare the area as you would for surgery.
   • SCALPEL BLADE (No15) - to perform a "cut down" (if required); this allows better visualisation if a vein is collapsed and helps to prevent catheters from bending
     Note: Local anaesthesia may be required.
3. A dressing will be required to keep the catheter in place; materials are largely a matter of personal preference, but generally used are:
   • TAPE STRIPS (Zinc Oxide tape, Elastoplast or Micropore 2.5cm) - to stabilise the catheter.
     Note: Elastoplast can be difficult to remove if applied directly to the skin, but Micropore does not provide such good adhesion.
   • COHESIVE BANDAGE - applied as a tertiary layer to provide additional stabilisation of the catheter and to prevent patient interference.
     Note: A restless patient may require splinting of the limb to prevent the giving set from becoming tangled around the affected leg; foam padding and conforming bandage will ensure that the splint is comfortable.
4. INTRAVENOUS CATHETER - a range of types and sizes are available; general properties are as follows:
   • Sterile.
   • Radiopaque.
   • Over-the-needle (as opposed to through-the-needle types).
   • Physiologically inert material to prevent irritation (e.g. Teflon or Polyurethane).
   • Luer attachment compatible with giving sets, injection taps, 3 way taps and T connectors.
   • Stylet for insertion.
   • Flexible once in place (Injection needles are unsuitable since they are very rigid and may cause venous damage).
     Some catheters are winged to enable them to be held more easily in place.
     Catheters are measured by the French gauge (Fg) - the gauge is the exterior diameter of the catheter. Always use the largest catheter possible to prevent occlusions.
     Common makes include Jelco and Optiva.
     
     
     

   GAUGE SPECIES SUITABILITY 24Fg Puppies, kittens and small cats 22Fg Large cats and small dogs 18/20Fg Medium and large dogs 18Fg Giant dogs

    

5. GIVING SET - the giving set transports the fluids from the infusion bag or syringe driver to the animal via the catheter. The giving set comprises:
   • Piercer to access the fluid bag.
   • Drip chamber.
   • Drip rate controller.
   • Length of plastic tubing (extensions are available if necessary).
     Normal giving sets deliver 15-20 drops/ml, while paediatric (burette) giving sets deliver 60 drops/ml.
     Special coiled giving sets are now available to help prevent the line from twisting.
6. FLUIDS - See key notes table for the types available and their indications. Always check the expiry date and examine the bag for leaks or cloudiness before use. The fluid bag should be removed from its protective outer layer and warmed to body temperature prior to administration. The fluid bag contains an inlet port for drip additives/drugs and an outlet port to which the giving set is attached.
   Always fill the giving set with fluids before administration, making sure that there are no air bubbles and that the drip chamber is half full.
   If only part of a fluid bag is to be used, CALCULATE THE LENGTH OF TIME FOR ADMINISTRATION OF FLUID AND AS A FAILSAFE, MARK THE LEVEL AT WHICH INFUSION MUST STOP.
7. INFUSION PUMP - Infusion pumps and syringe drivers are commonly used in hospitals. If available they should always be used since they are highly accurate. In syringe drivers, fluid is not administered directly from the infusion bag, but transferred to a syringe attached to the pump or driver. In modern infusion pumps, compatible giving sets can be directly used via the pump to deliver fluid. An alarm is incorporated which sounds when the transfusion stops. A special giving set is required, but a standard giving set can easily be adapted.
8. OTHER USEFUL EQUIPMENT:
   • Microwave or water bath to warm the fluids to 37°C prior to use.
   • Drip stand to hold the fluid bag; this must be higher than the patient.
   • T connector to enable intravenous drug administration at a site other than the injection site.
   • Rubber injection cap to plug the catheter but still allowing the administration of drugs.
   • Kink resistor; a small plastic device that prevents loops forming in the giving set tubing.
   • Incubator or heat pad for the patient; preferable if the animal is in shock.
   • Thermometer and stethoscope for monitoring the patient's vital signs.
   • Buster collar to prevent patient interference.
   • Heat retention jacket to maintain the temperature of the fluid bag.