• makes up 33% of the total body water and lies outside the cells

• includes the plasma within the blood, interstitial fluid between the cells and the transcellular fluid, which is formed by active secretory membranes (e.g. synovial fluid, cerebrospinal fluid and lymph)

• contains electrolytes (e.g. sodium, potassium, calcium, and magnesium, chloride, bicarbonate and phosphate) – sodium chloride is the predominant electrolyte

• plasma also contains proteins (e.g. albumin, globulin, fibrinogen, prothrombin) whose function is to maintain blood volume and blood pressure by exerting an effective osmotic pressure keeping fluid within the blood vessels. There is no protein in interstitial fluid as the molecules are too large to pass through the capillary walls under normal conditions.

• makes up 66% of the total body water and lies within all the cells

• contains electrolytes (e.g. potassium, magnesium and sodium, phosphate, bicarbonate and chloride) – potassium phosphate is the predominant electrolyte

• also contains proteins; these are non-diffusible and maintain an effective intracellular osmotic pressure.

1. Action: Obtain an accurate history from the owner asking questions about eating and drinking, urination, vomiting and diarrhoea, wounds, etc.

    Rationale: To provide you with an idea of the severity and cause of the problem. The facts will also guide you as to how best to replace the fluid loss.

2. Action: Weigh the animal.

    Rationale: This provides a measurement on which to base evidence of recovery or deterioration.

3. Action: Check for skin elasticity by tenting the skin and also check the eyes to assess whether or not they are sunken. Box 7.1 shows how to calculate the fluid deficit using clinical signs to estimate percentage dehydration.

    Rationale: Loss of skin elasticity and sunken eyes do not appear until the animal is approximately 5% dehydrated (Table 7.2). Older and wasted animals have reduced elasticity even though they may not be dehydrated; overweight animals only lose their skin elasticity when severely dehydrated.

4. Action: Check the mucous membranes.

    Rationale: These become tacky as a result of dehydration.

5. Action: Check the capillary refill time (CRT) by applying gentle pressure to the gum and observing the return to normal colour.

    Rationale: Capillary refill time is prolonged as a result of reduced circulating blood volume.

6. Action: Assess responsiveness of the animal by observing its response to the goings on around it – try calling it by name.

    Rationale: Severely dehydrated animals become moribund.

7. Action: Collect a blood sample and carry out a packed cell volume (PCV) assessment (see Ch. 4). Box 7.2 shows how to calculate fluid deficit using PCV.

    Rationale: PCV will be raised in a dehydrated patient. Every 1% increase in PCV corresponds to a 10 ml/kg fluid loss. PCV is reduced in cases of anaemia and if this is also present the result is unreliable.

8. Action: Collect a urine sample and measure the specific gravity (SG) using a refractometer (see Ch. 4).

    Rationale: Dehydration should cause an increase in urine concentration – the SG will rise – however, if there are underlying problems such as renal or hormonal disease the animal may be unable to concentrate its urine.

1. Action: Select and prepare the equipment (i.e. a bag of appropriate fluid, giving set, clippers, surgical scrub solution, swabs, disposable gloves, intravenous catheter and bowl).

    Rationale: Preparing all equipment in advance ensures a smooth efficient procedure.

2. Action: Check the expiry date on the fluid bag before opening it and check for any evidence of damage.

    Rationale: Any sign of damage and / or an out-of-date bag indicates that sterility may be broken and that there is a risk of infection.

3. Action: Warm the fluid bag by placing in a microwave or in a pan of hot water for a few minutes.

    Rationale: Prewarming the fluid prevents cold shock when the fluid enters the vein. Drip line warmers and drip bag cosies are available commercially.

4. Action: Wash your hands and put on a pair of disposable gloves.

    Rationale: It is important that this whole process is carried out as cleanly as possible to prevent the entry of infection through the vein.

5. Action: Remove the fluid bag from its outer covering and identify the outlet port. Hang the bag on a drip stand.

    Rationale: This facilitates handling and administration.

6. Action: Remove the giving set from its outer wrappings and switch off the flow control.

    Rationale: This prevents loss of fluid when you insert the giving set into the fluid bag.

7. Action: Remove the cover from the infusion spike and introduce it into the bag by pushing it through the outlet port.

    Rationale: Careful handling will avoid puncturing the bag resulting in fluid escaping from the bag.

8. Action: Squeeze the fluid chamber so that it fills by one-third.

    Rationale: To aid control of the fluid during administration and avoid the formation of bubbles.

9. Action: Remove the cap from the end of the line taking care to avoid touching a non-sterile surface.

    Rationale: It is important to maintain sterility at all times.

10. Action: Open the flow control and allow a small volume of fluid to run out into a bowl. At the same time check for air bubbles in the line – if necessary flick them with your finger to encourage them to disperse.

    Rationale: Take care to avoid loss of too much fluid as this will affect the volume that enters the patient. No air bubbles should be allowed to enter the circulation.

11. Action: When you are satisfied that everything is ready, close off the flow control, replace the cap on the end of the line and hang the flow line over the drip stand (some giving sets include small plastic clips).

    Rationale: The fluid is now ready to use and the flow line is kept out of risk of falling on the floor.

12. Action: Place the patient on a stable table and ask an assistant to restrain in sternal recumbency (see Ch. 1).

    Rationale: If the patient feels secure and comfortable it is less likely to try and escape.

13. Action: Select an appropriate vein and ask the assistant to raise it (see Ch. 1).

    Rationale: The cephalic vein is usually the easiest route of administration in dogs, cats. In rabbits the ear vein is useful.

14. Action: Clip the vein and prepare the area aseptically using a surgical scrub

    Rationale: It is vital to prevent the entry of infection into the vein.

15. Action: Insert an appropriate intravenous catheter into the vein and secure it with tape (see Ch. 1).

    Rationale: To ensure that the catheter does not come out of the vein and to protect it from damage by the patient.

16. Action: Remove the cap from the end of the flow line and attach the line to the end of the catheter.

    Rationale: This allows the fluid to run into the vein once the flow control is released.

17. Action: Release the flow control and observe the drip rate in the chamber. If necessary adjust the drip rate by manipulating the flow control. Box 7.3 shows you how to calculate the drip rate to correct a given fluid deficit.

    Rationale: Intravenous fluid should flow into the patient at a preset rate according to the requirements of the patient’s condition.

18. Action: Secure the lower part of the flow line to the paw with tape.

    Rationale: To prevent the line or catheter being torn out by the patient or by catching on objects.

19. Action: Instigate a monitoring routine by yourself or the nursing staff (Box 7.4).

    Rationale: A patient on a drip should never be left unattended for long periods. Monitor at regular intervals depending on the severity of the case and keep records on a fluid chart.

1. Action: Collect a small sample of donor blood in an EDTA tube and spin down at 3000 r.p.m. for 10 minutes.

    Rationale: EDTA will prevent clotting. The centrifugal force ensures that blood cells fall to the bottom of the tube.

2. Action: Draw off and discard the supernatant fluid.

    Rationale: The supernatant contains the plasma and the buffy coat, which are not needed.

3. Action: Resuspend the red blood cells in a little saline at 38°C.

    Rationale: This washes the red cells, which must be kept at blood temperature to ensure survival.

4. Action: Spin the sample again and remove the saline supernatant.

    Rationale: This leaves the washed red cells.

5. Action: Resuspend the red cells in a measured volume of warm saline to produce a 3–5% solution.

    Rationale: This produces a solution that is easier to work with.

6. Action: Collect a small sample of recipient blood in a heparinized tube and spin down in a centrifuge.

    Rationale: This is used to obtain plasma from the recipient.

7. Action: Place 1–2 ml of recipient plasma in a test tube, well plate or on a clean slide and add 1–2 drops of donor red cell suspension.

    Rationale: It is here that the reaction will be noted. The use of a slide produces a less reliable result.

8. Action: Gently mix by swirling the two liquids together and examine for evidence of haemolysis or agglutination.

    Rationale: Haemolysis is seen as reddening of the solution that does not separate out; agglutination is seen as irregular clumping within the solution, which forms a smooth button in the bottom of the tube.

9. Action: Compatibility is demonstrated by the absence of haemolysis or agglutination.

    Rationale: If the two blood samples are compatible there is no reaction.

1. Action: Select equipment required for blood collection.

    Rationale: Blood collection bag containing anticoagulant such as citrate phosphate dextrose, citrate phosphate dextrose adenine or acid citrate dextrose; cats require a specific feline collection bag. Local anaesthetic cream, syringes and needles of appropriate size, extension tubing, surgical gloves, swabs, skin scrub, clippers, electronic scales. In addition, cats require an i.v. catheter and a 500 ml bag of crystalloid i.v. fluid.

2. Action: Select a suitable donor.

    Rationale: See Table 7.3 for selection criteria in dogs and cats.

3. Action: If necessary, check for compatibility.

    Rationale: This is important if this is a second or subsequent transfusion or if further transfusions are anticipated as the risk of a transfusion reaction is increased.

4. Action: If necessary, sedate the animal. Cats may be given a general anaesthetic.

    Rationale: Most dogs will tolerate the procedure, but cats usually require some form of sedation or anaesthesia.

5. Action: Ask your assistant to firmly restrain the animal in a position allowing clear access to the jugular vein, on a stable examination table.

    Rationale: If the animal feels secure and comfortable it will be less likely to try and escape.

6. Action: Position the dog in lateral recumbency or in a sitting position. Cats are more comfortable in sternal recumbency with the forelimbs over the edge of the table and the head raised.

    Rationale: The position must be comfortable for the animal and must allow the jugular vein to be raised ready for venepuncture (see Ch. 1).

7. Action: Clip and prepare the site over the jugular vein within the jugular groove aseptically.

    Rationale: It is vital to prevent the entry of infection into the blood stream.

8. Action: Infiltrate local anaesthetic into the area around the vein and massage gently. Local anaesthetic cream may be used instead.

    Rationale: To desensitize the area making the procedure less painful.

9. Action: Ask your assistant to raise the vein.

    Rationale: See Chapter 1.

10. Action: Wearing surgical gloves, introduce the needle bevel-side uppermost into the vein and draw back on the syringe.

    Rationale: Blood should flow into the syringe as you draw back. If no blood appears check on the needle’s position.

11. Action: Detach the needle from the syringe and attach the needle to the tubing leading to the collection bag.

    Rationale: Blood will now begin to flow into the collection bag. Some collection bags have their own needle attached to the system.

12. Action: Position the bag lower than the animal and set it on some electronic scales.

    Rationale: Gravity will help the blood flow into the bag. The use of the scales allows you to monitor the weight of blood that has been collected. One ml of blood weighs approximately 1.053 g.

13. Action: Periodically invert the collecting bag.

    Rationale: To mix the blood with the anticoagulant in the bag.

14. Action: When the bag is full, clamp the tubing with a pair of artery forceps and remove the needle from the vein in the correct manner (see Ch. 1), applying pressure with a sterile swab for about 5 minutes.

    Rationale: One full bag (400 ml) is described as 1 unit of blood. Pressure will prevent the development of a haematoma.

15. Action: Apply a light neck bandage to the animal for several hours.

    Rationale: This will prevent haematoma formation and keep the site clean, preventing the entry of infection.

16. Action: If the blood is not to be administered immediately the tubing must be tightly clamped or heat sealed and labelled clearly with the species and date of collection. Blood can be stored at 4–8°C for a maximum of 3 weeks.

    Rationale: It is vital that infection does not enter the bag or that the blood does not deteriorate.

17. Action: Provide the donor with food and water and place in a warm, quiet kennel under observation for a few hours.

    Rationale: To make sure that the donor does not suffer from hypovolaemic shock.

1. Action: Select and prepare the equipment.

    Rationale: Bag(s) of blood, blood giving set, adhesive tape, bandage, patient (recipient) with large diameter i.v. catheter in place – this avoids red cell haemolysis.

2. Action: Make sure that the bag of blood is warmed to body temperature, particularly if it has been removed from storage.

    Rationale: To prevent cold shock and potential hypothermia.

3. Action: Hang the blood bag on a drip stand and set up the infusion set as described for fluid therapy. Insert the infusion spike into the correct port on the blood bag, taking care not to puncture the bag.

    Rationale: Puncturing the bag will cause leakage and may introduce infection.

4. Action: Squeeze both chambers of the infusion set to fill with blood to one-third in each of them (Fig. 7.1B).

    Rationale: The extra chamber within a blood infusion set provides a fibrin filter to collect any clots and prevent them from entering the circulation.

5. Action: Remove the cap from the infusion line and hold it over a bowl, making sure that you do not contaminate the tip.

    Rationale: It is essential to maintain sterility.

6. Action: Turn on the flow control to allow blood to flow through into the end of the line and out into the bowl. This must be done slowly to remove any bubbles and keep blood wastage to a minimum.

    Rationale: Bubbles must not enter the circulation as they may form an air embolism.

7. Action: Replace the cap on the end of the line and hang it over the drip stand ready for use.

    Rationale: Ensure that the equipment remains aseptic.

8. Action: Ask an assistant to restrain the patient within a warm comfortable kennel. The patient should be conscious or sedated and should be fitted with an intravenous catheter placed in the cephalic vein. Smaller exotics or neonates may be fitted with an intraosseus catheter (see Ch. 1).

    Rationale: Administration of a blood transfusion may take several hours and the patient must be warm and comfortable.

9. Action: Flush through the catheter with a small amount of heparinized saline in a syringe.

    Rationale: It is essential to check the patency of the catheter before attachment to the blood bag to avoid wastage of blood or unnecessary contamination.

10. Action: Remove the cap on the end of the fluid line and attach to the i.v. catheter. Switch on the flow control to allow the blood to flow into the patient.

    Rationale: If the blood is not flowing freely, check the catheter and reflush with heparin.

11. Action: When flowing freely, adjust the flow control to achieve the correct flow rate to deliver the required volume (Boxes 7.5 and 7.6).

    Rationale: Rapid transfusion should be avoided to prevent circulatory overload or reaction.

12. Action: Attach the line securely to the patient by means of tapes and bandages.

    Rationale: The line must be secure to avoid leakage or interference by the patient.

13. Action: Monitor the patient constantly for any signs of reaction. Record everything on the hospital chart.

    Rationale: Transfusion reactions require immediate attention and the patient must not be left for long periods on its own.

    The patient should be monitored every 15–30 minutes during the transfusion. Afterwards it should be checked within 1 hour, 12 hours and 24 hours.

14. Action: You should check for the following parameters:

    Rationale: Any abnormalities in these parameters may indicate a transfusion reaction.