Chronic Renal Failure Pt. 3: Subcutaneous Fluids

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By Karen Harrison Binette

We hear from readers looking for help with CRF issues all the time. This is part three of a three part series from The Cat Doctor on the diagnosis and treatment of this all too common condition in cats.

by Lori Horwedel, client educator at The Cat Doctor, Philadelphia, PA.

In our last two posts, we discussed Chronic Renal Failure and how it is managed. Today, we’re going to give step-by-step instructions on how to administer subcutaneous fluids, one of the key treatments for animals with renal disease.


Ali has been receiving subcutaneous fluids for several years now

Why do we give subcutaneous fluids?

There are a number of reasons why a cat might require fluid administration under the skin at home. Chronic kidney disease is probably the most common reason because CRF kitties need extra fluids–beyond what they are able to drink–to flush renal toxins out of their systems. Sometimes a sick patient will not reliably drink enough water and extra fluid administration is required, or perhaps an oral injury may preclude drinking and thus extra fluids are needed. In any case, if you are reading this, fluids under the skin have probably been recommended for your pet, you have received a demonstration on fluid administration, and this guide is meant as a handy “tip sheet’ for when you are on your own at home with your pet.

*Disclaimer: Subcutaneous fluids should not be administered without the direction and supervision of a veterinarian. *

What you will need:

Needles: Needles come in various sizes. The rule of thumb is the lower the number, the faster the flow (but this also means the needle is bigger). Find the lowest gauge your cat will tolerate.

Needles by size. The lower the gauge number, the larger the needle and the faster the fluids will flow.



Fluid Bag:

Each number on the bag represents 100ml of fluids.


In addition to the supplies, you will need a place from which you can hang the fluid bag (the higher the better, as gravity will help the fluids flow more quickly). We recommend the top of kitchen cabinets, towel hooks on the back of bathroom doors, and bed posts. You can hook the top of the bag over a hanger and use the top of a door or a clothing rack as well. Depending on your pet, you might also need an assistant to hold kitty while the fluids are being administered.



The first order of business will be connecting the line to the bag and running water through the line to clear it of air.

Step one: Pull the tab out of the bottom of the bag

Step two: remove cap from the pointy end of your fluid line

Step three: Insert the line into the bag. You will need to use some force to push it as far as it will go

Step four: Tilt the bag upright and squeeze fluid into the chamber until it is about half full–this will allow you to see how fast the fluids are flowing

Step five: Unclamp the roller clamp by rolling it upward. Unclamp the pinch clamp as well, and allow fluid to flow through the line until the air is gone. Reclamp one of the clamps

Unclamp the pinch clamp as well, and allow fluid to flow through the line until the air is gone. Reclamp one of the clamps

Screw the cover off the back of a needle and remove the cover from the end of the line. Screw the needle firmly on the end of the line

Hang the setup in the designated place and get your kitty ready. We recommend positive reinforcement to distract your cat during the process; a meal, brushing, a catnip toy, or petting can help relax your kitty during this new experience.

Once kitty is settled in, it’s time for fluids! Make sure you know how much you’re giving and when to stop the flow before you get started. Once you’ve mentally prepared yourself and Fluffy is settled in, you’re ready to start!


Find loose skin around Kitty’s scruff and make a “tent.” Insert the needle parallel to the angle of your cat’s back

A note here: try to be confident when inserting the needle. You will feel a little pop when the needle goes through the skin. Push forward until this happens, then stop.


Remember the roller clamp? Roll it up to open it. *Sometimes the line crimps under the clamps. Squeeze it open if this happens.*

Open the pinch clamp as well. Don’t forget to check for crimping!

Now, if all has gone according to plan, the fluids are flowing! You should see either a fast drip or a steady flow of fluids in the chamber that rests just below the bag. You will also see a bubble forming under your kitty’s skin. If the fluids don’t seem to be flowing or they’re dripping very slowly, check the line for crimping under both clamps, and make sure the clamps are both open. You can try gently moving the line a few inches in either direction to re-position the needle without removing it from your kitty. If they still will not flow, you can start over.

If the fluids start flowing but you notice they’re leaking, you can try backing the needle out very slightly; sometimes this can stop a leak. If not, remove the needle and start over.

A kitty sitting for his fluid therapy


Many cats will relax and sit still for fluids, but some will need to be held in place. Keep an eye on the level of fluids in the bag, and stop the flow by clamping the line off when you reach the correct amount. Once you’ve clamped the line, you can gently remove the needle and recap it.

Things to keep in mind:

You’ll want a clean needle with each treatment, both to prevent contamination and because the needles get dull very easily
You’ll need an opaque plastic container to dispose of needles. Alternately, you can collect them and return them to your veterinarian’s office for disposal
Some cats react strongly to room-temperature fluids–if your environment is cool, the fluids can be warmed by placing the bag in warm water for a few minutes before administration
A bulge at the fluid site is normal, but should be absorbed into the body before you are next due to give fluids. If the bulge does not absorb, call your veterinarian
Occasionally, you might see a small amount of blood when you remove the needle. No need to panic; there are tiny blood vessels under the skin that can bleed.

Ali again. What can we say, she likes being the SQF spokeskitty!


Remember, if you’re having trouble, you can always talk to your veterinarian about another fluid demonstration; we understand that this can be daunting for some people! However, many people find that once they get the hang of it, administering fluids at home is fairly easy. Most importantly, fluids can improve your kitty’s quality and quantity of life after a CRF diagnosis.


The Cat Doctor is a full service medical and surgical facility exclusively for cats. Established in 1983, in the Art Museum area of Philadelphia, the hospital has served the Philadelphia community well for over twenty years, providing excellent comprehensive and compassionate care.

The Cat Doctor works with local rescues and animal welfare organizations, and is well known to readers who followed the case of Clark Kent. In cooperation with rescue group City Kitties, The Cat Doctor cared for Clark after he was found, cold, wet, abandoned and near death, and provided photos and updates for his thousands of supporters and well-wishers.

The practice also maintains an active Facebook page, where visiting cats and staff mascot and blood donor kitty Diamond get their pictures and updates posted regularly.

This article is reprinted with permission from their website, where it is posted here.

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1 thought on “Chronic Renal Failure Pt. 3: Subcutaneous Fluids”

  1. I to found this a very interesting article .I lost my 12 year old pet cat to renal failure. He had the fluids given while at the hospital and my visits 2x’s daily.wanted to give him every chance . I had done the fluids with a pet dog years ago But he to became so wary of the needles we ended it as a treatment after several weeks.

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