"Intravenous" means the
fluids are given into a vein.
As with humans, this
treatment is usually only used in a hospital setting.
fluids are therefore normally reserved for acute situations. In the case
of a CKD cat, this would often be when a cat is severely dehydrated
They may also
be used for cats with pancreatitis, or kidney stones or kidney infections, or before and
What are Intravenous Fluids?
Intravenous (IV) fluids are a form of fluid therapy whereby the fluid is
administered via a drip feeding into a vein (intravenous). If you've ever
been a patient in hospital, you were probably on intravenous fluids, which
are sometimes referred to as "a drip."
The fluid used is not simply water
because you cannot simply inject ordinary water into the body, you need to
use a fluid which is compatible. One commonly used fluid type is
lactated ringers solution (LRS), which is isotonic, i.e. it has the
same sodium concentration as body tissues.
Fluid therapy for critically ill dogs and cats
(2005) Schaer M Presentation to the 30th World Small Animal Veterinary
Association World Congress discusses the use of IV fluids. This is a
rather technical presentation for the layperson.
Where to Use Intravenous Fluid Therapy
skilled form of treatment, and great care needs to be taken to ensure the
rate of fluid flow is correct for the cat - too fast a flow can be
dangerous (it can overtax the heart), too slow a flow may not rehydrate
the cat quickly enough.
this, IV fluids are usually only given at the vet's office, where the cat
can be carefully monitored. If you are giving fluids at home, you are
subcutaneous fluids, not IV fluids.
When to Use Intravenous Fluid Therapy
IV fluids are used to support cats who are sick for a variety of reasons.
Introduction to fluid therapy (2008) Dr S
DiBartola states "The intravenous route is preferred when the patient is very
ill, when fluid loss is severe, or when fluid loss is acute."
Critically Ill Cats
As explained on the
page, intravenous fluids are often used to treat acute problems e.g. to
stabilise a critically ill animal who has lost a life-threatening amount of
body fluids, perhaps following a road traffic accident, or a cat who has been
They are also used to treat cats who are critically ill for other reasons,
such as our George on the left who was extremely ill at this time with
IV fluids are commonly used for severely dehydrated cats. Since CKD cats are
prone to dehydration because of their increased urination, which may then be
compounded by the cat not eating and/or drinking enough, it is not
uncommon for CKD cats to become dehydrated enough to require IV fluids. This
is sometimes referred to as crashing, and may well be the first sign that your cat has CKD.
In most cases, cats in this situation will have high bloodwork with creatinine
over 6-7 mg/dl (US) or 550-650 Ámol/l (international). The IV fluids are employed as a flushing through of the kidneys to correct an acute crisis situation of severe dehydration and any resulting electrolyte imbalances, and
to remove toxins from the
blood. Flushing the kidneys in this way is known as diuresis.
IV fluids are also used for cats who have suffered an
acute insult to the kidneys (acute
kidney injury), such as a kidney infection or
In some cases, IV fluids may succeed in flushing out kidney
Cats with Other Ilnesses or Concerns
IV fluids may also be used for cats who need additional support
for some other reason. Cats with
often require IV fluids when first diagnosed. Cats with severe
diarrhoea or vomiting may become dehydrated and need IV treatment,
as may cats who are not eating or drinking for some reason other
Cats Receiving Anaesthesia
Cats who are undergoing anaesthesia are often also placed on IV fluids,
particularly CKD cats. Anaesthesia can reduce blood flow through the kidneys
and cause falls in blood pressure, which may further damage the kidneys, but giving IV fluids to the cat during
the procedure reduces this risk.
Goals of Intravenous Fluid Therapy for CKD Cats
In terms of CKD patients, the primary aim of IV fluids is usually to
rehydrate a severely dehydrated cat. Dehydration is very unpleasant and
can make cats look and feel very ill, but they usually look and act much
better once dehydration is under control.
As a side effect, the cat's kidney bloodwork should improve. The goal is
not to lower the bloodwork values as such, but this usually will happen,
because the dehydration is making the bloodwork look artificially
Speed and Length of Intravenous Fluid Therapy
How much intravenous fluid to give each day and the drip rate (how fast the fluid
flows into your cat) is a complex calculation, based on various factors
such as your cat's weight and the degree of dehydration. Your vet is
trained to do this.
Most CKD cats need to stay on IV fluids for 2-4 days. For a severely dehydrated
cat, the first 2-4 hours are used to rehydrate the cat i.e. the severe
dehydration is quickly corrected. This is known as the replacement phase. Cats stay on IV for longer than this
though, usually for several days: this is the maintenance phase which is
designed to give the cat a chance to stabilise.
IV fluids should not be stopped suddenly, but should be reduced gradually
so as to give the cat's kidneys time to adapt. If IV fluids are being
given to a severely dehydrated CKD cat, most vets will start this
weaning process once there are no longer any improvements in the cat's bloodwork.
This tends to be measured over 1-2 days, so if a cat's creatinine level is
unchanged on Day 3 from Day 2, that is when the vet would start gradually
reducing fluids with a view to discharge probably on Day 4 if the cat
Managing fluid and electrolyte disorders in renal
failure (2008) Langston C
Veterinary Clinics Small Animal Practice38 pp677ľ697
says "When serum creatinine
concentration reaches a baseline value (ie, when it no longer decreases
despite IV fluid therapy), fluids should be tapered in preparation for
patient discharge. After a period of intensive diuresis, fluid
administration should be tapered gradually over approximately 2 to 3
One day on IV is unlikely to be sufficient for most cats to restore hydration
and some degree of balance; so I am
concerned by the number of vets I hear about who offer just one day on IV, then
say the cat's numbers have not improved after that short stint, and
recommend euthanasia. In most cases this is inappropriate in my opinion (and
is not what Dr Langston recommends in the previous paragraph). Yes,
not every CKD cat can be saved; but euthanasia is an irrevocable decision so
you need to be very sure, and for most people that means giving their cat
every chance. For a severely ill cat, one or two days on IV are simply not
going to be long enough, so I would recommend that you make sure that your cat
is given a reasonable stint on IV of 3-4 days if you can afford it. If your
cat's bloodwork is still improving, your cat may stay on IV even longer,
occasionally cats are on IV for as long as a week.
IV catheters can usually remain in place for 72 hours before there is any risk
of infection; after this, a catheter can be placed in the other paw if
If Bloodwork Does Not
Improve With Intravenous Fluids
Don't be too despondent if your cat's bloodwork does not improve after a
few days on IV. In fact, sometimes the bloodwork actually worsens after
1-3 days on IV. Some vets may recommend euthanasia if this occurs, but
don't feel obliged to agree to this, especially if you are in the USA
where your cat is probably receiving IV fluids in the ER. Vets in the ER
are usually emergency medicine specialists who are used to dealing with
acute situations; they often have a lot less experience of cats with
chronic diseases and may not realise that further improvement may occur.
This may not even necessarily occur while the cat is in hospital but may gradually
happen once you take
your cat home and use sub-Q fluids.
Thomas is a good example of a cat who did not respond
dramatically to IV fluids, but they did help stabilise him, and he
continued to improve once he came home. Initially Thomas was on IV for
four solid days and nights, and only began to eat a little on day 3. He
had urea of 89 Ámol/L (BUN: 241 mg/dl) at diagnosis, and it did not
actually improve after four days and nights of IV either. But he was
rehydrated and acting better in himself by the end of the four days, so we
took him home. He had his good and bad days, which were influenced in
particular by his severe anaemia, but with home
ESA and other treatments over a
number of weeks he improved and began to enjoy life again. Eventually his numbers
reduced to urea 27
(BUN: 76) and creatinine 316
(US: 3.57 mg/dl), where they stabilised for some months.
Monitoring Cats on
Cats on IV fluids need
close monitoring to ensure they do not become overhydrated, which is a
strain on the heart. The cat should be checked once an hour, and heart and
lungs should be checked every 3-4 hours. The cat should be assessed by a
vet at least once every twelve hours and weighed regularly. The following
should be routinely monitored:
the weight of the cat
such as potassium and sodium levels
fluid output (urination)
many American vet offices do not have anybody present at their premises
overnight, so some of these tests cannot be performed for several hours,
which is potentially very risky.
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 Association49(3) pp149-159 state
"Patients with a
high risk of fluid
overload include those with heart disease, renal disease, and patients
via gravity flow."
I personally would not feel at all
comfortable leaving a cat on IV fluids unattended. If your vet recommends
IV fluids for your cat, but s/he would be left alone overnight, a possible
compromise is for your cat to be on IV fluids at the vet's office during
the day, but to come home (with catheter still in paw) overnight. Ideally
though, your cat should be on IV fluids continuously but under
may add treatment for
excess stomach acid to the IV fluids. Ask if this is being done
because if it is not, your cat may need oral medication instead.
Helping Your Cat on Intravenous
If you agree to
have your cat put on IV fluids, ask for him/her to be put in a quiet area
as far away as possible from any canine in-patients. Leave a blanket or an
old item of clothing with your smell on it in the cage to comfort your
Your cat will do better if s/he keeps his/her strength up by eating, so make
sure your cat is fed during hospitalisation. Some vets will tell you that
your cat is receiving nutrients and calories from the IV fluids, but a
litre of lactated ringers contains only around 10 calories, which is not
enough. They may also tell you that your cat is being fed, but they are
simply placing food in front of the cat and do not ensure that the cat
actually eats the food. Ask them to assist feed your cat is necessary, or
consider the use of a feeding tube. See
Persuading Your Cat to Eat for more
Some people believe that they should not visit their hospitalised cat
because the cat may find it distressing. I don't agree with this, I think
it is better for both the cat and the caregiver if regular visits take
place, preferably daily. This also enables you to feed your cat yourself during your visits. The
Persuading Your Cat
to Eat page has tips on getting food into your cat.
What to Expect After IV Fluid Therapy
When your cat comes home from a session on IV fluids in
hospital, don't expect him/her to bounce back immediately. Most cats are
exhausted - if you've ever been in hospital, you'll know how hard it can
be to sleep well there - so fatigue and lethargy are normal. Your cat will
probably not drink much either - s/he will be well hydrated from the IV
fluids. Many cats hide, which indicates they are not feeling 100%. Give
Most cats need a few days at home convalescing before they
begin to act better.
Appetite may take some time to return, or your cat may
need a little help in this department, perhaps treatment for excess stomach acid
or an appetite stimulant.
Most CKD cats who have been on IV fluids will need sub-Q
fluids at home if they are to avoid crashing again. You probably won't
need to start sub-Qs as soon as you return home because your cat will be
nicely hydrated from the IV fluids but you will probably need to start
a couple of days after returning home. Bring a few basic supplies home
from the vet, and then check
Supplies Cheaply to find sources for obtaining the supplies you need
If your vet believes IV
fluid therapy is the best treatment for your cat, you should give it very serious
consideration - it really can be lifesaving.
When Not to Use Intravenous Fluids
IV fluids are not always a benign
treatment, plus they are can be stressful for your cat and
expensive for you. Therefore they should therefore only be used
I occasionally hear of vets putting
CKD cats with low or medium level numbers (creatinine around 3-3.5
mg/dl (US) or 260-300 Ámol/l (international) on
IV fluids. In most cases this is unlikely to be necessary, because most cats
would not be dehydrated at this level. However, it may be
appropriate if a cat is very dehydrated despite the low bloodwork, perhaps
from vomiting or diarrhoea, or if there are other issues present, such as
infection, kidney stones or pancreatitis.
IV fluids are not a suitable treatment for ongoing hydration purposes:
they are too taxing on the kidneys and, since they increase the GFR (see
CKD?), they could accelerate the loss of kidney function if done for
too long; plus of course they entail a stay in the vet's office, which
many cats find very stressful and which is also very expensive.