Types of Fluid Imbalance
Fluid therapy is usually required because of an imbalance in the cat's
body fluids.
Managing fluid and electrolyte disorders in renal
failure (2008) Langston C
Veterinary Clinics Small Animal Practice 38 pp677–697 says
"kidney failure typically leads to derangements of
fluid, electrolyte, and acid-base balance."
According to the
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159, there
are three main types of fluid disturbances:
Volume Changes
The amount of fluid in the body is out of balance, such as when a cat is dehydrated or when s/he has suffered blood loss for
some reason.
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159 state
"Hypovolemia refers to a decreased volume of fluid in the vascular
system with or without whole body fluid depletion. Dehydration is the
depletion of whole body fluid. Hypovolemia and dehydration are not
mutually exclusive nor are they always linked...Common causes of hypovolemia include severe dehydration, rapid fluid
loss (gastrointestinal losses, blood, polyuria), and
vasodilation."
Content Changes
The body's fluid composition is out of balance, such as when
blood potassium levels are too high (hyperkalemia) or too low
(hypokalaemia). Hyperkalaemia may be seen in particular when a cat has a
blockage, such as
kidney stones, or
acute kidney
injury.
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159 state
"If life-threatening hyperkalemia is either
suspected or present (K 6 mmol/L), begin fluid therapy immediately along
with medical therapy for hyperkalemia." This will normally be in the
form of
intravenous fluids.
See Potassium for
more information on hyperkalaemia.
Distribution Changes
Fluids are in parts of the body where they should not be, such as
ascites (fluid in the abdominal cavity). This may happen for various
reasons, such as if the cat has heart disease or cancer, or if the cat is
given too many fluids.
Fluid Imbalances in CKD Cats
For most CKD
cats, the main problem is volume changes in the form of dehydration.
Occasionally a CKD cat will also have problems with content changes or
with distribution changes (the latter is often associated with concomitant
heart disease).
Fluid Therapy Phases
According to
Fluid and electrolyte therapy (1998)
Wingfield WE Colorado State University College of Veterinary Medicine, there
can be three phases for fluid therapy:
Emergency Phase
The goal is
usually to stabilise a critically ill animal who has lost a
life-threatening amount of body fluids, e.g. because of a road accident.
This will normally be in the form of
intravenous fluids
in a hospital setting.
Fluid therapy in the emergency feline patient
(2010) Hetzel N Feline Update Spring 2010 discusses
the use of fluids in emergency situations.
As a person with a CKD cat, you will usually not be concerned with this
phase, though occasionally cats who suffer severe blood loss will be in
the emergency phase:
Replacement Phase
The goal is
usually to correct dehydration, which may be
very severe in some cases, such as in a CKD cat who has
crashed.
This will normally be in the form of
intravenous fluids
in a hospital setting.
Maintenance Phase
The goal in
this phase is to
keep the cat's hydration status properly balanced. If the cat has just
received replacement fluids, initially the maintenance phase will also be
performed in hospital
via
intravenous fluids
until the vet is sure the cat is
now stable. Maintenance fluids in a hospital setting are usually also
necessary for cats who are not eating or drinking.
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159 say "Urine production
constitutes the majority of
fluid loss in healthy patients. Maintenance fluid
therapy is indicated for patients that are not eating or drinking, but do
not have volume depletion, hypotension, or ongoing losses."
Once the
cat is stable,
subcutaneous
fluids (sub-Qs or sub-cuts are commonly used for maintenance purposes.
Introduction to fluid therapy
(2008)
DiBartola SP Idexx Laboratories FAQ states "The subcutaneous route is convenient
for maintenance fluid therapy in small dogs and cats." Most cats who
require sub-Qs are given these at home by their caregiver.
Types of Fluid Therapy
There are
a number of different types of fluid therapy.
Introduction to fluid therapy
(2008)
DiBartola SP Idexx Laboratories FAQ states "The route of fluid therapy depends on the nature
of the clinical disorder, its severity, and its duration." Your vet will decide which
is the best method for your cat.
Oral Fluids
Oral fluids, including drinking and the water contained in food, are the best way for CKD cats to manage
their hydration needs. They are cheap, easy and safe.
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159 state
that oral fluids are appropriate when the "Gastrointestinal
tract is functional and no contraindications exist (e.g., vomiting)."
Unfortunately CKD
cats may eventually not be able to take in sufficient fluids orally to
manage their hydration needs. Even if they can do so, they may need
support on a temporary basis if they have problems with vomiting or
diarrhoea, which increase body fluid losses, or if they have pancreatitis. In such cases some of the other
methods described below will probably also be necessary.
Go to
Oral Fluids
Subcutaneous Fluids (Sub-Qs or
Sub-cuts)
Subcutaneous fluids are fluids which are injected under the skin with a small needle.
Sub-Qs are much easier to give than intravenous fluids (see below) and
most people are able to learn how to give them at home.
Sub-Qs are normally used when
the cat can no longer drink enough to remain hydrated, which in practice
tends to be once creatinine levels are
consistently over 3.5-4.0 mg/dl (USA) or 300 -350 µmol/l (international). This equates to high Stage 3
of the IRIS staging system.
They may also be needed on a temporary basis for cats who develop problems
with vomiting or diarrhoea, which increase body fluid losses, or for cats
with pancreatitis.
Introduction to fluid therapy
(2008)
DiBartola SP Idexx Laboratories FAQ states that "The subcutaneous route is convenient
for maintenance fluid therapy in small dogs and cats."
2013 AAHA/AAFP fluid therapy guidelines for dogs and
cats (2013) Davis H, Jensen
T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of
the American Animal Hospital Association 49(3) pp149-159 state
that sub-Qs are used for "Anticipated dehydration or mild
fluid volume disturbances in an outpatient setting ...Subcutaneous fluids
are best used to prevent losses and are not adequate for replacement
therapy in anything other than very mild dehydration."
This page
explains more about when to start sub-Qs, how much to give and how often,
and how to cope with giving them.
Go to Subcutaneous Fluids
Subcutaneous Fluids Tips
This page discusses the pros and cons of the different
fluid types (Lactated Ringers, Normosol etc.) and which other supplies to
choose, such as needles. It also gives
helpful tips on how to make things go as easily and smoothly as possible
for you and your cat.
Go to Subcutaneous Fluids Tips
How to Give Subcutaneous Fluids with an IV
Administration Set
This page is
a photographic guide to giving
fluids with an IV administration set (also known as a venoset or a giving set).
This method is commonly used in the USA.
Go to
Subcutaneous Fluids with a Giving Set
How to Give Subcutaneous Fluids with a
Syringe
This page
is a photographic guide to giving
fluids with a syringe. If you are allowed to do sub-Qs in the UK, you
will probably be offered this method.
Go
to Subcutaneous Fluids with a Syringe
Winning Your Vet's Support
Many people outside the USA and Canada will find that their vet is reluctant to
allow them to give sub-Qs at home. This page gives suggestions on how to
ask your vet to permit you to try sub-Qs if they are appropriate for
your cat.
Go to Subcutaneous Fluids: Winning Your Vet's Support
Intravenous Fluids (IV Fluids)
Intravenous fluids
are fluids given into a vein ("on a drip").
This treatment is normally only used for cats who are hospitalised, so it
tends to be reserved for cats who are in crisis (which is sometimes
referred to as "crashing"),
or who have acute
kidney injury or
kidney stones; it may also be appropriate for cats with severe vomiting or diarrhoea.
Introduction to fluid therapy
(2008)
DiBartola SP Idexx Laboratories FAQ states "The intravenous route is preferred when the
patient is very ill, when fluid loss is severe, or when fluid loss is
acute."
Intravenous fluids are also used to support cats undergoing surgery under
anaesthesia, such as
dental surgery.
Go
to Intravenous Fluids
