Fluid therapy recommendations for dogs and cats

1. FLUID THERAPY IN
COMPANION
ANIMALS

2. INTRODUCTION
 Important life saving procedure
 Assessment of the condition
 Advanced blood tests
 Organ function studies
 Never become reluctant
 Fluid and electrolyte imbalances
 Selection of correct fluid

3. CONSTRAINTS
Availability of fluids
Sedation necessary sometimes
Xylazine in the dog
Ketamine in the cat
Busy doctor
Patience of the client
Availability of minimum infrastructure

4. GENERAL CONSIDERATIONS
Water comprises 60-70%
70% in young and lean animals
50% in old and obese animals
Fluid not existing as single units
Different compartments
Fluid moves between compartments
In shock no adequate fluid for carrying oxygen

5. Sources of body water
Diet (major source)
Drinking water
Metabolic water
Body looses water in 3 ways:
Urinary loss
Faecal loss
Inevitable/insensible loss
Inevitable loss is uncontrollable, such as
respiratory, and cutaneous.

6. Water losses
24-Hour Body Water Loss:
Fecal loss is 10 to 20ml/kg/24hrs
Urinary loss is 20ml/kg/24hrs
Inevitable loss is 20ml/kg/24hrs
Total loss = 50 to 60ml/kg /24hrs

7. • 50-60ml/kg are lost every day in adult dogs
• 80ml/kg are lost every day in pups and kittens
• This is due to their less ability to concentrate urine
• If 50-60ml/kg fluid is lost every day, then it has to be compensated
• That is known as the maintenance fluid requirement is 50-60ml/kg/day
or precisely 50ml/kg/day

8. BODY FLUID COMPARTMENTS
Let us suppose approximately 60% of BW is water.
Out of this 75% is intracellular (ICF)
25% is extracellular (ECF)
ECF is seen in 3 places:
Intravascular fluid (approximately 24% of total ECF)
Interstitial fluid (approximately 72% of total ECF)
Trans cellular fluid (approximately 4% of total ECF).
Trans cellular fluid is the small amount of fluid as
CSF, synovial fluid, etc.

9. DISTRIBUTION OF FLUIDS
DISTRIBUTION OF FLUIDS
Total body
Water
60%
ICF
75%
ECF
25%
ISF
72%
IVF
24%
TCF
4%

10. • All the fluid compartments are separated by semi permeable
membrane.
• Electrolytes are dissolved in these fluids.
• The amount of electrolytes differ within each of the body’s fluid
compartments, so water content differs, too.
• The chief electrolytes in ECF are sodium, chlorides and bicarbonates.
• The chief electrolytes in ICF are potassium and magnesium.

11. Composition of body fluids
COMPOSITION OF BODY FLUIDS
(mmol / L) Intra
vascular
Interstitial ICF
CATIONS
Sodium 142 145 10
Potassium 4 4 150
Calcium 2.5 2.4 4
Magnesium 1 1 34
ANIONS
Chlorides 104 117 4
HCo3 24 27 12

12. •Cell membranes are permeable to sodium.
•The sodium-potassium pump mechanism (Na+/K+-
ATPase pump mechanism) inside the cell helps the
potassium to always be intracellular.
•This pump uses adenosine triphosphate (ATP) as the
energy source.
•Thus, more potassium is maintained intracellular than
outside the cell.
•If sodium creeps inside the cell it will be driven out by
the sodium-potassium pump.
•So, sodium is the chief extra cellular cation and
potassium the chief intracellular cation.

13. • Fluid compartments in the body are not of the same size.
• Thus, fluid loss from a small compartment has a greater effect than loss
from a large compartment meaning fluid loss from an intravascular
compartment produces more impact than fluid loss from an intracellular
compartment.
• If somebody takes a sip from a large glass of beer, it goes unnoticed.
However, if sipped from a small thimble, it is clearly noticeable.

14. •So, when fluid is lost from one compartment, the
body tries to ensure the loss is evenly distributed to all
compartments. Therefore, if fluid is lost from one
compartment, fluid from the neighboring
compartment moves through the semi-permeable
membrane to spread the loss evenly.
•This also means that when water is lost from the body,
some water is lost from all compartments as the body
attempts to redistribute the remaining fluid.
•Depending upon the size of the compartment, this
may be of greater or lesser importance.

15. MOVEMENT OF FLUIDS
MOVEMENT OF FLUIDS
ICF ISF IVF TCF

16. REGULATION OF CHANGES IN BODY WATER
Regulation happens in 2 ways.
• When fluid loss occurs it stimulates the osmoreceptors and there will be an
increase in thirst. This stimulates water resorption from the renal tubules,
increasing the concentration of urine and thereby decreasing the urine volume.
• Another mechanism is the kidneys detecting reduced plasma volume resulting
from reduced renal supply and perfusion. Renal ischemia stimulates the
production of rennin, and angiotensin is generated that releases aldosterone.

17. This acts on the distal convoluted tubule (DCT) for
more sodium reabsorption, ensuing water
reabsorption, and subsequent concentrated urine
and oliguria.
•This happens reversely, too. If there is low plasma
osmotic pressure due to hypoproteinemia, less ADH
will be produced and less resorption of sodium and
fluids from the DCT. This stimulates fluid loss to
effect dilute urine with polyuria.

18. SHOCK
• Shock is an acute circulatory collapse.
• There will be sudden reduction in circulating or intravascular body
fluids.
• There will be vital organ ischemia causing symptoms.
• Insufficient oxygen and nutrients are carried to vital organs. If left
untreated, shock will lead to rapid death.

19. SIGNS OF SHOCK
• Low mental alertness and depression
• Cold, pale, dry mucous membranes
• Prolonged CRT
• Cyanosed or injected mucous membranes
• Tachycardia
• Weak and rapid pulse
• Oliguria
• Reduced or raised body temperature
• Slow, shallow breathing

20. POSSIBLE CAUSES OF SHOCK
• Anaphylactic shock
1. Allergens, such as drugs and in blood transfusion
2. Endotoxins, such as in pyometra
• Neurogenic shock
• Vasogenic shock
1. Dehydration produced by vomiting and diarrhea
2. Hemorrhages such as internal and external origin

21. TREATMENT OF SHOCK
•The principal aim is to restore vascular volume and
fluid therapy is the only means to save the patient’s
life. When we increase the cardiac output by fluid
therapy, it increases the oxygen delivery to vital
organs.
•Other measures in treatment of shock are considered
secondary to fluid therapy.
•IV fluid therapy is essential.
•The choice of fluid is of huge importance.
•How much is give is more important than what is
given. In a crisis, any fluid is better than no fluid at all.

22. •Initially give 20 ml/kg IV colloids, if available, followed
by 60 ml/kg crystalloids (Ringer’s solution/RL), or if
colloids are unavailable, then hypertonic saline, or
even RL.
•In complete collapse and a vein cannot be got, select
the intra osseous route.
•When stable, look for the PCV and plasma proteins.
•If PCV is below 25%, then repeat IV.
•If plasma protein is below 4gm/100 ml, then repeat IV.
•Reassess the PCV until it reaches 40%.

23. •Look for the basic cause of shock using clinical
investigation.
•Look for primary heart diseases. If primary heart
disease is present, avoid an overload of fluids
•Follow IV fluid therapy by crystalloids, such as RL.
•Ensure that the dog urinates. If not, stop everything.
•Give warmth to the patient
•If any infections are present, as in septic shock, give
antibiotics
•Even though the use of corticosteroid is still
controversial, administer 5mg/kg IV Dexamethasone.

24. ASSESSMENT OF FLUID BALANCE
• The commonest fluid loss is a mixed loss of water and electrolytes.
• Assess the level of electrolytes, especially potassium, an important part of fluid
therapy.
• Dehydration can be assessed by: clinical history, clinical examination and
laboratory results.
• Assessment of Central Venous Pressure (CVP) is uncommon.

25. FLUID LOSS
When there is excess fluid loss an animal becomes dehydrated.
Fluid loss can happen by 3 ways:
• 1. Primary water loss
• 2. Mixed water and electrolytes loss
• 3. Blood loss
The choice of fluid depends upon the type of fluid loss

26. PRIMARY WATER LOSS
• There is absolute reduction in water intake.
• This happens in facial injury, mouth, tongue trauma, etc.
• General weakness and lethargy occurs.
• There is an increased excretion of water, as in diabetes insipidus and
renal disease.
• Here, there are no electrolyte disturbances.

27. WATER AND ELECTROLYTE LOSS
This is the commonest type of loss in animals.
• Situations, such as vomiting, diarrhea, wounds, burns, pyometra and
ascites cause this type of loss and can produce mixed loss.
• Electrolytes are chemicals, such as sodium, potassium, and
magnesium.

28. BLOOD LOSS
This is due to hemorrhage.
• Hemorrhage can be external or internal. External is visible, internal is
not.
• Generally, we cannot diagnose and manage internal hemorrhage in
our field conditions.

29. POTASSIUM
• This is mainly intracellular cation.
• An imbalance in potassium content causes bradycardia, arrhythmia,
lethargy, etc.
• If left untreated, the patient dies suddenly.
• The condition has to be assessed whether it is
hypokalemia/hyperkalemia.

30. POTASSIUM BALANCE
•Potassium enters the body through diet and is
excreted by the kidneys.
•In starvation, dietary entry is restricted and so
hypokalemia occurs. So consider the importance of
potassium ions in the body.
•If hypokalemia is determined, then potassium has
to be added to the fluid.
•In hyperkalemia, potassium supplementation is
totally restricted, e.g. renal insufficiency, Addison’s
syndrome, etc.

31. HYPOKALEMIA AND HYPERKALEMIA
Decreased in:
•Prolonged starvation
•Long standing vomiting
•Prolonged diuretic therapy
•Prolonged diarrhea
Increased in:
•Urethral obstructions
•Bladder rupture
•Acute Renal Failure

32. ASSESMENT OF DEHYDRATION
All the methods now used to assess dehydration in
animals are rough estimates. No methods are
available that provide complete accuracy. In clinical
practice, 4 main methods are used to determine the
level of dehydration, either directly or indirectly, with
a fair degree of accuracy in some methods. The main
methods are:
•Clinical History
•Clinical Examination
•Laboratory Analysis
•Clinical Measurements

33. CLINICAL HISTORY
•Ask the client about the clinical history.
•Each vomit will lose approximately 4ml/kg fluid from
the body.
•Each bout or episode of diarrhea will lose 4ml/kg fluid
from the body.
Examples:
•A 10kg dog has vomited twice, the fluid loss is
calculated as 4ml x 10kg x 2 vomits = 80ml fluid loss.
•If a 20kg dog has 3 episodes of diarrhea, then fluid
loss = 4ml x 20kg x 3 episodes = 240ml of fluid loss.

34. CLINICAL EXAMINATION
•Skin elasticity/skin turgor is assessed at the scruff of
the neck. Here, the skin in-between the shoulder
blades is pulled and released to calculate the time
taken to recover. Normally, the skin falls back in 2 to 3
seconds.
•Normal capillary refilling time (CRT) is less than 2
seconds. This is assessed by the delay in reddening of
the gum over the canine tooth when pressed and
released with a finger.
•The mucosa becomes dry and blanched.
•The patient may have sunken eyes and appear
depressed.

35. CLINICAL SIGNS
• Below 5% - not detectable.
• 5 to 6% - slight loss of skin elasticity.
• 6 to 8% - marked loss of skin elasticity, slightly prolonged CRT, slightly
sunken
eyes, dry mms.
• 10 to 12% - tented skin stands in place, CRT above 2 secs, dry mms,
sunken
eyes.
• 12 to 15% - early shock, collapse, death.

36. EXAMPLE
• A cat is presented with 4kg BW with 10% dehydration. Calculate the
fluid requirement.
10/100 x 4kg = 0.4kg = 400ml

37. LABORATORY ANALYSIS
• The following tests can be used:
• PCV increases in dehydration
• Hemoglobin increases in dehydration, but MCHC will be normal
• Total plasma proteins will increase
• Blood urea increases
• Creatinine increases to a certain extent
• Plasma electrolytes increase or decrease
• Acid-base estimation
• Packed cell volume (PCV) measures the proportion of RBCS packed in
the centrifuge tube
• Increases in dehydration
• For every 1% increase in PCV, approximately 10ml/kg fluid loss occurs
• The standard of 45% PCV in dogs and 35% PCV in cats is adopted for
routine calculations.

38. EXAMPLE
Example:
• A 5kg cat has 45% PCV. Calculate the fluid loss.
• Normal PCV of cat is 35%. Here increase by 10%. So, 10% x 10ml x
5kg = 500ml fluid.

39. CLINICAL MEASUREMENTS
Body Weight
• Changes in body weight can give an approximate estimate of fluid
loss.
• For this, the body weight before dehydration should be known.
• Drawback is that dog owners do not know their pet’s body weight.

40. WHICH FLUID AND WHY
Blood products, colloids and crystalloids are the 3 main fluid types.
• To understand where the fluid goes after the fluid therapy, a basic
knowledge of fluid distribution in the body is needed

41. WHOLE BLOOD AND BLOOD PRODUCTS
Used In:
• Severe hemorrhages
• Anemia
• Specific problems, e.g. von Willebrand disease where platelet
suspension is given IV.
• Blood transfusion is impractical in our field practice.

42. COLLOIDS
• Fluids that contain large molecular sized ions designed to remain in
vascular space longer than other fluids.
• These fluids can expand the plasma volume.
• The high osmotic pressure draws fluid from the interstitial space into
the plasma to expand its volume and hence the name ‘plasma
volume expanders’.

43. Colloids are used generally in:
1. Hemorrhage
2. Shock
3. Severe dehydration
Since blood is not very easily available in the field, colloids can be used in
hemorrhages.
Examples of colloids:
1. Dextrans – very expensive
2. Gelatins e.g. Haemaccel (should be stored in room temperature)
3. Plasma (not available here).

44. CRYSTALLOIDS
• These are group of sodium based electrolyte fluids. Since they have a
low molecular size, they extravasate from the vascular bed and
disperse in the interstitial space.
• Mostly similar to plasma water in composition.
• If the renal function is normal, it is normally excreted through urine.

45. RINGER’S LACTATE
• Isotonic to ECF and contains sodium, potassium, calcium, chloride
and lactates.
• Lactates are metabolized to bicarbonates if the liver function is
normal.
• Since bicarbonates are formed after RL administration, and the pH
increases, this fluid is regularly used against metabolic acidosis

46. SALINE
• This is 0.9% sodium chloride solution which does not contain
potassium and is isotonic to body fluids. Used when plasma
potassium levels are increased due to some underlying disease.
• Can be used in primary water loss or hyperkalemia as in renal
dysfunctions.

47. 5% DEXTROSE
• Isotonic to body fluids.
• No electrolytes are added. If administered, this gives isotonic body
water and a small amount of glucose for energy, though negligible.
• Used in primary water loss.

48. 10% DEXTROSE
• Slightly hypertonic.
• Choice in liver diseases.
• Fair supply of dextrose for energy.
• Readily compensates body water.
• No electrolytes that can be given safely.
• Can be given in fluid retentions such as ascites.

49. DNS
• Isotonic fluid, mainly water and small amounts of sodium and
chloride to replace daily urinary losses in normal animals.
• Used in primary water loss.
• If used as a maintenance fluid, potassium can be added if needed.

50. RINGER’S SOLUTION
• Isotonic to blood, contains sodium, chloride and potassium, but no
lactates.
• Indicated in water and electrolyte loss with some potassium loss.
• Mainly used in pyometra.
• Hypokalaemia occurs in pyometra due to continuous vomiting in
advanced stages.
• There, this is the fluid of choice

51. DARROW’S SOLUTION
• Hypertonic solution containing sodium, chloride and potassium than
RL.
• Mainly used in metabolic acidosis with potassium deficiency, e.g.
persistent diarrhea.

52. HYPERTONIC SALINE
• This is 7.8% or 9% sodium chloride.
• Hypertonic to body fluids.
• Immediately after administration IV, it draws fluid from interstitial
spaces and increases the vascular fluid volume.
• Thus, this can generally be used in shock.
• The dose is 4 to 5ml/kg/BW.

53. CLINICAL SITUATIONS REQUIRING FLUIDTHERAPY
•Blood loss
•Primary water loss. Here 5% dextrose, DNS, etc. can
be used
•Loss of water and electrolytes as in vomiting and
diarrhea.
•In acidosis, bicarbonates are needed (RL).
•In acidosis, Sodium bicarbonate can be added to
crystalloids.
•In metabolic alkalosis, RL should not be given.

54. ACID-BASE BALANCE
• Normal pH of blood is 7.35 – 7.45
• pH below 7.35 is acidosis and pH above 7.45 is alkalosis
• The body keeps hydrogen ions at a constant level and control pH
through
1. Renal system
2. Respiratory system
3. Using buffers

55. RENAL SYSTEM
• Kidneys excrete or retain bicarbonates in DCT
• It is of great importance
• If there is a renal impairment, then the pH also changes

56. RESPIRATORY SYSTEM
•The respiratory system controls the levels of carbon
dioxide in the body.
•H2O + Co2 react to form carbonic acid.
•Carbonic acid can at any time break down into
water and carbon dioxide or hydrogen ions and
bicarbonates according to the need.
•If carbon dioxide is expired and not allowed to
dissolve in water, the pH of blood remains constant.

57. • In lower respiratory rates, carbon dioxide accumulates, carbonic acid
forms and acidosis occurs or we can say, in acidosis, tachypnea occurs.
• In high respiratory rates, carbon dioxide is more depleted, less hydrogen
ions are formed, pH rises and alkalosis occurs or we can say, in alkalosis,
oligopnea occurs.

58. COMMON CAUSES OF ACID-BASE DISTURBANCE
•Metabolic acidosis
Occurs in renal failure, ruptured bladder, urethral
obstructions, lower UT diseases, shock.
•Metabolic alkalosis
Occurs in vomiting, over administration of
bicarbonates during fluid therapy.
•Respiratory acidosis
Acute respiratory obstruction / failure, severe
lung diseases, respiratory depression.
•Respiratory alkalosis
Hyperventilation in pain, fear, etc.

59. CALCULATING FLUID REQUIREMENTS AND
FLOW RATES
• Calculate the fluid required to compensate the loss that is the deficit.
• Maintenance fluid volume is always 50ml/kg/day.
• The sum of these two is known as the total fluid requirement

60. Calculation 1:
A 10kg dog is presented. It seems 5% dehydrated.
Calculate its fluid requirement for the next 24
hours.
Deficit = 5% dehydrated = 5/100 x 10kg = 0.5kg =
500ml
Maintenance = 50ml/ kg/24 hours x 10 = 500ml
Total fluid volume for 24 hours = 500 + 500 = 1000ml
(1Litre)/24 hours

61. Calculation 2:
A 4kg cat is presented with a normal 37% PCV. Now it is dehydrated and
the PCV is 49%. Calculate the fluid requirement for the next 24 hours.
Deficit = PCV increase by 12%
For each 1% increase, loss is 10ml/kg
So deficit = 12% x 10ml x 4kg = 480ml
Maintenance = 50 x 4 g = 200ml/day
TFR (total fluid requirement) = 480ml + 200ml = 680ml/24 hours

62. Calculation 3:
A 20kg dog is presented that requires fluid at twice maintenance.
Calculate the TFR over the next 24 hours.
Normal maintenance = 50ml/kg/day x 20kg = 1000ml/24 hours
Twice maintenance = 2 X 1000 = 2000ml/24 hours (2L)

63. DRIP RATE
•The drip factor is written by the manufacturer on the drip
set packet.
•Number of drops per ml of fluid is the drip factor -
commonly 15 or 20 drops.
•Determine the fluid deficit in ml.
•Determine 24 hours maintenance in ml.
•Determine the amount of fluid in ml hour (TFR divide by 24).
•Determine the fluid requirement in ml/min (divide by 60)
•Determine the amount of fluid in drops per minute (ml/min
x drip factor).
•Determine number of drops in how many seconds by
dividing 60 with number of drops per minute.

64. Calculation 4:
A 10kg dog requires 500ml of fluid to be administered over 24 hours to
replace losses and 500ml for maintenance. The set has a drip factor (DF)
20. Calculate the drip rate.
Fluid deficit = 500ml, Fluid maintenance = 500ml. Thus, TFR = 1000 ml
Fluid per hour = 1000/24 = 41.6ml/hour
Fluid per minute = 41.6ml/60 = 0.69ml/min
Seconds/drop = 60/13.88 = 4.3 (4) sec
Means 1 drop in every 4 seconds.

65. Calculation 5:
A 5kg GSD puppy has acute vomiting and diarrhoea.
Vomited 10 times, passed 5 fluid motions. What is the
TFR over the next 24 hours? DF is 60. What is the drip
rate?
Deficit = 4ml x 5kg x 10 vomits = 200ml
4ml x 5kg X 5 diarrhea = 100ml
Total fluid deficit = 200 + 100 = 300ml
Maintenance = 50ml/kg/24 hours
i.e. 50ml x 5kg = 250ml over 24 hrs

66. TFR = 550ml
Fluid required per hour = 550/24 = 22.9ml/hour
Fluid per minute = 22.9/60 = 0.38 ml / minute
DPM = 0.38 x DF 60 = 22.8 DPM
Seconds for 1 drop = 60/22.8 = 2.63sec (3)
That means total fluid requirement at a drip rate of 1 drop per 3
seconds for 24 hours.

67. Calculation 6:
A 25kg GSD suffering from heat stroke and fluid is to be given
at twice the rate of maintenance over 24 hours. Calculate
the fluid requirement. DF is 20. Calculate the drip rate.
Maintenance = 50ml/kg/24 hours
Thus, 50 x 25kg = 1250ml/24 hours
Twice this maintenance = 2 x 1250 = 2500ml/kg/day
Fluid rate per hour = 2500/24 = 104.1ml/hour
Fluid per minute = 104.1ml/hour/60 = 1.73 ml/minute
DPM = 1.73 ml / min X DP 20 = 34.7 dpm
Seconds for 1 drop = 60/34.7 = 1.7 seconds (2)
Drip rate = 1 drop per 2 seconds.

68. Calculation 7:
A 3kg cat just had surgery. It is to receive 1.5 times total daily
maintenance fluids over the next 8 hours. DF is 60. Calculate
the fluid requirement and DR.
Maintenance = 50ml/kg/day = 50 x 3kg = 150ml
1.5 times of this = 1.5 x 150 = 225ml
225ml is to be given over 8 hours
That is, 225/8 = 28.1ml/hour
Fluid volume per minute = 28.1ml/hour divided by 60
=0.46ml/minute
DPM = 0.46 x DF 60 = 28.1 DPM
Seconds for one drop = 60/28.1 = 2.1 seconds (2)
That means 1 drop every 2 seconds over 8 hours.

69. ACUTE FLUID LOSS
In acute fluid loss or shock, 25% is given rapidly during the first hour of
treatment and the remainder for the rest of the decided time slowly.
Plasma volume expanders (colloids) are generally given by this
principle.

70. Calculation 8:
A 20kg weighing Dalmatian is 10% dehydrated. It is decided to
replace 25% of the deficit in the first hour of fluid therapy
and the rest over 23 hours. Calculate the fluid requirement
and the volume to be given first.
Deficit = 10% of 20kg = 2L
Maintenance fluid = 50ml/24 hours x 20 g = 1L over 24 hours
Total fluid requirement = 2 + 1 = 3L
25% of the total deficit = 25% of 2L deficit = 500ml
So, total fluid requirement = 3 liters
Volume to be given in the first hour = 500 ml
Remaining fluid in the remaining 23 hours.

71. ROUTES OF ADMINISTRATION
There are 6 routes of administration:
• Oral route
• Intravenous route
• Intra peritoneal route
• Subcutaneous route
• Rectal route
• Intra osseous route

72. • The oral route can be chosen if the patient is co-operative or without emesis.
The oral route fails if the patient continually vomits. In small pups or kittens, this
may be the easiest route. If it has vomiting, oral DOMSTAL DROPS
(Domperidome) are recommended followed by oral fluids.
• The recommended route for all fluids is the intravenous route.
• Through the intra peritoneal route, about 50% of the fluid will be absorbed
rapidly.

73. • The subcutaneous route cannot be chosen in shock due to low
cutaneous supply. Neither can hypertonic fluids be given through this
route.
• The rectal route can be chosen in some infants and neonates.
• When it is difficult to get the vein in IV, then it is better to choose the
intra osseous route, especially in infants and neonates.