ANSWERS

1. What is the chief objective of fluid therapy?
   Restoration of an adequate volume of circulating fluid in the animal's body.
2. List signs of dehydration and shock.
   • Polydipsia.
   • Pallid mucous membranes (CRT < 2 secs).
   • Dry mucous membranes.
   • Cold extremities and hypothermia.
   • Oliguria.
   • Excessive blood loss during surgery or following trauma.
   • Loss of skin elasticity ("tenting").
   • Collapse or coma in critical cases.
   • Slow or failed recovery from general anaesthesia.
   • Sunken eyes.
   • Rapid weak pulse.
3. What is hypovolaemic shock?
   Shock resulting from reduced blood volume following haemorrhage or severe burns.
4. What are the 2 main sources of body water?
   • Ingestion of fluids and foods.
   • Metabolism of fats and carbohydrates.
5. Within what period of time should existing fluid deficits be replaced?
   Within 24 hours.
6. What are inevitable or insensible water losses?
   Water losses that cannot be regulated by the body. They are dependent on the ambient temperature and the necessity of the body systems to use water. The term insensible is used because these losses continue even at times of water deprivation.
7. List routes for inevitable fluid losses.
   • Respiration.
   • Cutaneous losses/sweating.
   • Defecation.
8. List routes for sensible fluid losses.
   • Urination.
   • Lactation.
9. Approximately how much water loss occurs in terms of body weight over 24 hours?
   • Urinary losses = 20mls/kg.
   • Faecal losses = 10-20mls/kg.
   • Respiratory and cutaneous losses = 20mls/kg. To maintain water balance in a healthy cat or dog approximately 60mls/kg/day are required. Cats generally require more water than dogs.
10. What type of blood sample is required for an acid-base balance estimate?
    Arterial blood in heparin (usually collected from the femoral artery).
11. What 3 parameters are measured when estimating acid-base balance?
    • pH.
    • Bicarbonate ion concentration.
    • Carbon dioxide tension.
12. What are the normal ranges of urine specific gravity in a cat and dog?
    • Cats 1.020-1.060
    • Dogs 1.015-1.045
13. How can the specific gravity of urine be a useful measurement in the assessment of dehydration?
    A dehydrated animal will produce urine that is more concentrated than normal. Therefore, a high specific gravity measurement is to be expected.
14. Define dehydration.
    Reduction of total body water and the symptoms associated with excessive loss of fluid. Persistent vomiting or diarrhoea may cause dehydration, or lack of water intake.
15. What are the 4 main causes of primary water depletion?
    • Deprivation of drinking water.
    • Pyrexia or excessive panting.
    • Diabetes insipidus.
    • Conditions resulting in prolonged inappetance.
16. Mixed water and electrolyte depletion is more common. What may give rise to this condition?
    • Persistent vomiting.
    • Persistent diarrhoea.
    • Gastrointestinal obstruction.
    • Pyometra.
    • Wound drainage (especially burns which may result in high protein losses).
17. What is the most common electrolyte lost and why?
    Sodium. This is the main cation of the ECF.
18. What is the medical term used to describe a deficiency of blood sodium?
    Hyponatraemia.
19. What might possible causes of hyponatraemia be?
    • Congestive heart failure.
    • Hepatic fibrosis.
    • Renal disease.
20. Hypernatraemia describes high blood sodium; what possible causes can you list?
    • Dehydration.
    • Diabetes insipidus.
    • Diarrhoea.
    • Osmotic diuresis.
    • Sea water ingestion.
21. What is the medical term for potassium depletion?
    Hypokalaemia.
22. In what cat breed may hypokalaemia be congenital?
    The Burmese.
23. List possible causes of hypokalaemia.
    • Vomiting.
    • Diarrhoea.
    • Chronic renal failure.
    • Malnutrition.
    • Diuretic drugs.
    • Infusion of excessive fluids deficient in potassium.
    • Hyperaldosteronism.
24. Hyperkalaemia describes high blood potassium; what may give rise to this condition?
    • Urinary obstruction.
    • Oliguric renal failure.
    • Hypoadrenocorticism.
    • Severe soft tissue trauma.
25. A client telephones the surgery; the symptoms described lead you to believe that his cat may be suffering from dehydration. What questions might you ask in order to assess the seriousness of the situation?
    • Is the cat eating normally or suffering from anorexia (loss of appetite)?
    • Is the cat drinking normally or polydipsic (drinking more than usual)?
    • Have there been any episodes of vomiting or diarrhoea; and if so how frequently and for how long?
    • Is the cat urinating more than usual (polyuric)?
    • Is the cat unable to urinate (oliguric)?
    • Has the owner noticed any abnormal discharges?
    • Have there been any blood loss or other traumatic fluid losses?
    
    IF DEHYDRATION IS SUSPECTED, ALWAYS ADVISE THE CLIENT TO BRING THE PET TO THE SURGERY AS QUICKLY AS POSSIBLE. THE ANIMAL'S HEALTH WILL DETERIORATE RAPIDLY UNLESS PROMPT TREATMENT IS GIVEN.
26. What percentage dehydration is usually fatal?
    10-12%.
27. How is capillary refill time (CRT) assessed?
    The tip of your index finger is pressed firmly onto the patient's gum. Upon release of the pressure, the area will appear white. The return of blood to the region and subsequent return to a pink colour will occur within 2 seconds in a healthy animal. A dehydrated or shocked animal will often have a CRT of >2 secs.
28. What laboratory tests may be useful in the assessment of dehydration?
    • Packed cell volume (PCV). For every 1% increase above normal, a fluid loss of approximately 10mls/kg of body weight may be estimated.
    • Haemoglobin estimation. Elevated haemoglobin levels may be evidence of dehydration.
    • Total plasma protein. Raised plasma protein may be indicative of dehydration.
    • Electrolyte levels. Sodium, potassium and chloride parameters may be affected in the dehydrated animal. They may be elevated or deficient depending upon the cause of dehydration.
    
    LABORATORY ASSESSMENTS OF DEHYDRATION MUST NEVER BE RELIED UPON AS 100% ACCURATE SINCE UNLESS NORMAL RESULTS FOR THAT PARTICULAR ANIMAL ARE KNOWN, ONLY AN ESTIMATE OF THE DEGREE OF ABNORMALITY MAY BE MADE. PRE-EXISTING DISEASE MAY ALSO AFFECT THE RESULTS.
29. What dog breed is predisposed to a high PCV?
    The greyhound.
30. What clinical measurements may be made to monitor the progress of a patient undergoing fluid therapy?
    • Body weight.
    • Urinary output.
    • Central venous pressure.
31. What is the normal urine output of an animal per hour?
    1-2mls/kg/hr.
32. How is central venous pressure (CVP) measured, and what is the normal range?
    CVP is the pressure recorded by the introduction of a jugular catheter into or near to the right atrium of the heart. It is measured with a manometer. Normal CVP is 3-7cm of water. CVP measures the filling of the great veins which is a balance between central blood volume, vascular tone and the contractile ability of the heart.
33. What would a high CVP measurement be indicative of?
    Overhydration. A high CVP may also be as a result of occlusion of the catheter, or right ventricular heart failure. A low CVP indicates dehydration.
34. What should be monitored at least 3 times daily when a patient is undergoing fluid therapy?
    Body temperature.
35. How does pyrexia affect fluid requirements?
    For every 1 degree C increase in body temperature, fluid requirements increase by 3mls/kg.
36. What is the shock dose fluid therapy rate?
    60-80mls/kg/hr.
37. A cat is on fluid therapy following an RTA. The veterinary surgeon asks you to monitor the cardiovascular system; what checks would you carry out?
    • Pulse rate, rhythm and strength.
    • Mucous membrane colour.
    • Capillary refill time.
    • Chest auscultation.
    • CVP if the equipment is available.
38. In addition to monitoring the cardiovascular system, a patient on fluids also requires attention to the respiratory system. What regular checks are prudent?
    • Respiratory rate and depth.
    • Chest auscultation (for detection of pulmonary oedema).
    • Mean arterial blood pressure measurements.
    Note: A Key Notes table - Monitoring The Dehydrated Patient - accompanies this module.