Subcutaneous Fluid Therapy

Subcutaneous fluids (also known as sub-Q’s or Lactated Ringer’s solution) are fluids that are administered through a needle which is inserted under the cat’s skin. Each bag contains 1000 ml. (one liter) of solution and must be prescribed by your veterinarian. While some cats in CRF may never need them, most eventually do. Sub-Q fluids are an essential and ongoing part of CRF management. As the disease progresses, the cat may stop drinking, not drink adequate amounts of water or vomit frequently and become dehydrated. Sub-Q fluids help with rehydration. Without adequate hydration, the blood flow through the kidneys is reduced which causes even more rapid deterioration of the kidneys. Subcutaneous fluid therapy will not repair the kidneys, but will help the remaining kidney tissue function as effectively as possible.

The fluids may be supplemented with potassium if your veterinarian feels it is appropriate for your cat’s particular situation. CRF cats may be able to live for several additional years with sub-Q fluids and the proper diet. The need is generally determined by the creatinine and BUN numbers. Cats really do seem to feel better after hydration so it is well worth doing.


No treatment is perfect for all patients. While sub-Q fluids have extended the lives of countless CRF cats, cats with heart conditions can be put in extreme danger through the administration of sub-Q fluids. Also, excessive fluids can put pressure on the pleural cavity and temporarily collapse a lung.

Volume and Frequency

The amount of sub-Q’s per injection is based on the cat’s weight and the severity of the disease. The frequency can also vary depending on how much the disease has progressed. Never give your cat a greater volume of sub-Q fluids than your vet has specified. Some cats can do quite well on sub-Q fluids once a week while others who are farther along in the disease can benefit from daily injections. Some cats simply will not tolerate sub-Q fluid injections and quality of life versus quantity must be seriously considered. In later stages of CRF, your cat may reach a point where it can no longer absorb the sub-Q fluids.

The Water Pouch

The injection of sub-Q fluids may cause your cat to look somewhat lumpy and off-balance for a short time. The cat may carry the water pouch up to 24 hours until it’s absorbed. It is normal for fluid (sometimes slightly blood-tinged) to leak from the injection site for a short time. After hydration, the water pouch usually slips down to the bottom of the abdomen, but occasionally it may slip down into one of the front legs. The pouch is not as noticeable on a long-haired cat as it is on a shorthair.

Administering Sub-Q’s at Home

Administering sub-Q’s can be done at home and your veterinarian or technician can train you. Practice at the veterinarian’s office the first few times so you’ll feel more competent doing it at home. Don’t feel bad if you can’t bring yourself to do it. Most vet’s offices will give the fluids on a regular basis, but the cost will be quite a bit more than doing it yourself and the cat may be more stressed out by frequent trips to the veterinarian’s office.

Lactated Ringer’s, IV lines and needles may be purchased at lower prices through veterinary supply houses. A prescription from your veterinarian will usually be required.

Some Tips for Administering Sub-Q’s at Home

  1. Always check the fluid bag for holes and leaks before using. This is done by gently squeezing the bag. If there is a hole, the fluids have been contaminated. Dispose of it and start with a new bag.
  2. You may find it is easier as a two-person job, one to distract, pet, talk to and hold the cat firmly and one to administer the fluids.
  3. If possible, choose an area in your home that has a window for the cat to look through and be distracted. If you are a two-person team, have one person amuse the cat by dangling a toy in front of him. Try diverting the cat with the smell of tuna on your fingers.
  4. Warming the fluids will make the experience more comfortable for the cat. You can warm the fluid bag to just body temperature with warm water in the sink. ALWAYS test the temperature of fluids, just as you would test the temperature of a baby bottle, on the inside of your wrist, before administering fluids. The fluids should feel tepid to the touch.
    Note: We do NOT recommend using a microwave to warm your cat’s sub-Q fluids. Microwave temperatures vary and can heat unevenly. NEVER forget that overheated fluids can do great harm to a cat.
  5. Hang the bag from a planter hook or cupboard handle which will give height to increase the speed of the flow.
  6. Place the cat on a slick surface like a counter or tabletop so it will be harder for him to grab on to anything. Or you may find it helpful to confine the cat in a box, carrier, bathtub or sink and then stuff towels around him so that he’ll be less likely to squirm around and jerk the needle out. You can also wrap a towel around the cat to confine him. The soft carriers with zippers at the top also can be used for confining the cat and administering the sub-Q fluids at the same time. Check with your veterinarian about using a restraint bag.
  7. An #18 gauge needle will make the procedure go faster, but may be more painful for the cat. A #20 gauge needle is smaller and is less painful, but fluid injection goes slower. It depends on what your cat will tolerate.
  8. Make note of each insertion site and alternate between sites each time you administer the fluids. Using the same insertion point over and over may cause scar tissue to build up and eventually cause difficulty when inserting the needle.
  9. The hardest part is getting the needle in far enough so that it doesn’t easily pop out and not so far that it goes all the way through the ‘tent’ and out the other side. Also, you may hit muscle in which case the cat will feel it and react and the flow will stop. You have to move the needle around inside slightly sometimes to keep a good flow going.
  10. Never use the needle more than once. If you drop the needle or the cat jerks it out, ALWAYS start over with a new needle rather than risking contamination. The needles are extremely sharp, so be careful not to jab yourself.
  11. Don’t get discouraged. If you or your cat becomes stressed out during the sub-Q, stop and try again later. There are times your cat may tolerate the fluids quite well and just won’t at other times. Cats seem to pick up on our vibes, so stay calm and if it doesn’t go well one day and you don’t get the entire dose in, just do the balance later that day or the next. As time goes on, you’ll begin to feel like a pro and wonder why you were so worried about this.
  12. After the sub-Qs are done, give your cat a treat or some favorite food. Cats may tolerate the sub-Qs better if they come to expect that something good will come immediately afterward.
  13. Ask your veterinarian about returning used needles and equipment for safe medical waste disposal. You may also purchase a Sharps container for storage (inquire at your pharmacy) or make your own container. Label a ziplock bag or closed container, such as a coffee can or plastic soda bottle, “used”, and place the used needles in it to avoid using them again. Tape the lid when the container is full. Mark your homemade containers with a biohazard label. Store them in a safe place away from children and animals. For more information, see: How should I dispose of syringes, needles, lancets, and other ”sharps?” .
  14. Although fluid bags are well sealed and the tubing is designed to prevent contamination, the safest way to store partially used bags is in the refrigerator. Warming the bag for the next session then becomes an absolute necessity.