Subcutaneous Fluid Administration in Dogs: Bag Method

Why did my veterinarian recommend at-home subcutaneous fluid treatment?

Supplemental fluids can benefit dogs with a variety of medical conditions. Home fluid therapy is most commonly recommended for dogs with chronic kidney disease (also known as chronic renal failure).

If your dog is diagnosed with a condition that will benefit from fluid therapy, your veterinarian can teach you to administer fluids subcutaneously (under the skin).

Do not be alarmed — it is normal to feel hesitant or apprehensive about administering any treatment to your pet. Giving injections is outside the comfort zone for most outside the medical profession. 

However, subcutaneous fluid administration is not nearly as difficult as it sounds. The benefits your dog receives will make it well worth your time to learn this simple technique.

There are two ways to give subcutaneous fluids at home: using a fluid bag with a drip set or using a syringe with a butterfly catheter. The syringe method offers more control, while the bag method is ideal for giving larger volumes and often works faster.

How do I prepare the equipment?

The equipment for home fluid therapy typically consists of a bag of fluids, a fluid drip set, and a needle. The fluid drip set is simply a tube that connects the fluid bag to the needle; it is also called the “tubing” and the “fluid line”. 

A member of your veterinary healthcare team will go through the steps with you in person. 

The steps are as follows:

1. Remove the fluid bag and the fluid drip set from their protective packaging.

2. Find the line lock in the middle of the tubing (also called the fluid line). Close the line lock by moving the roller so it squeezes the tubing. The lock on a new fluid set is usually set in the open position.

3. Find the exit port on the bottom of the fluid bag. Pull the protective cover off this port, exposing a hole that will accept the pointed end of the fluid set. 

4. Remove the protective cap from the top (pointed) end of the fluid set.

5. Push the pointed end of the cap into the open hole of the fluid bag, puncturing the bag as it goes in. Attach it firmly to prevent leaks.

6. Hold or suspend the fluid bag about 3 feet (1 meter) above the level of your dog’s head. To keep the bag elevated, place a hanger through the hole at the top of the fluid bag, and hook it over something high, like a door. Fluid should now flow freely through the tubing.

7. Gently squeeze and release the bulb at the top of the drip set until the bulb chamber is about half-full of fluid.

8. Next, remove the protective cap on the lower end of the fluid set and fill the tubing with fluid from the bag by opening the line lock you closed earlier. Be sure that all large air bubbles run out of the tubing and that you don’t let the lower end of the fluid set touch anything.

9. Once the tubing is full, close the lock again, by moving the roller downward.

10. Replace the protective cap on the lower end of the fluid set.

11. Open the protective wrapping around the needle so that the open end (not the sharp end) is exposed. Do not allow the open end of the needle to touch anything.

12. Once again, remove the protective cap from the lower end of the fluid set and place the open end of the needle on it. Press it on firmly. Some lines have a spinning lock that can be twisted over the edge of the needle to lock it in place. You may now discard the protective cap.

How do I insert the needle and administer fluids?

1. Prepare the fluids. Your veterinarian will tell how much fluid to give your dog for their condition. If you are administering fluids in two places on your dog, give half the amount in each location.

2. Choose a comfortable location where you will treat your dog. If your dog is smaller, this may be on a table, countertop, or your lap. If your dog is larger, this may be on the floor. Be sure that both of you are in a position that will be comfortable for about 5–10 minutes. The end of the fluid set should reach your dog without much tension.

Tip: Some small dogs are more cooperative if they are placed in a box not much larger than the dog. Some dogs like being wrapped lightly in a towel; sometimes, just covering the head will relax the dog. Experiment with different locations and techniques until you find one that is comfortable for you and your dog. Your dog may seem nervous the first few times, but most are comfortable by the fourth or fifth administration.

3. Pinch and lift a roll of loose skin, creating a tent-like shape, in one of the locations shown in the illustration:

• At the level of the shoulder blades, along the midline between the left and right sides.
• At the level of the back legs, just to the right and to the left of midline, along the hips.

4. Lay the point of the needle at the base of the roll of skin (the bottom of the “tent”). Keep the needle horizontal and pointing toward the dog's head (assuming that the dog is in an upright or standing position).

5. Advance the needle slightly forward while pulling the roll of skin towards the needle. Make this motion firm and steady, not shaky and timid. This motion will place the point of the needle just under the skin.

6. Release the roll of skin. The point of the needle should remain under the skin.

7. Grasp the line fluid lock in one hand. Move the roller upward to start the fluids flowing.

8. Watch the line of fluids in the bag as it goes down, to ensure you give the recommended amount. The line starts at the highest amount (e.g., 1000 mL) and decreases as the fluids are given. If your vet recommended 100 mL, and you start at 1000 mL, you will stop when the line hits 900 mL.

9. When you have given the prescribed amount of fluid, stop the flow by firmly pushing the roller in the line lock downward. If you do not close it well, and the bag is left hanging, fluid will leak out. Some bags have an additional slide closure on the fluid line. You can close this additional device after you have removed the needle from your pet's skin.

10. Remove the needle from the skin and replace the needle’s protective cap. Be careful to avoid injuring yourself.

11. Remove the used needle from the drip set and place a new, sterile needle on the line to prevent contamination.

How should I store and dispose of syringes and needles?

Store the syringes with new, sterile needles to prevent contamination. Keep the equipment in a safe place until the next fluid administration. The fluids should be kept in a relatively cool location out of direct sunlight but do not refrigerate. Be sure to keep this and all medications out of the reach of children and pets.

Dispose of needles in a designated “sharps” container or in a firm, sealable, plastic container. Ask your veterinarian where to safely dispose of the container.

What other tips should I know?

• It is usually not necessary to "sterilize" the skin with alcohol before inserting the needle. Wiping a little alcohol on the skin does not really sterilize it and the odor and feel of alcohol may aggravate your dog.
• Ideally, the fluids should be given at about body temperature. Most dogs tolerate fluid administration quite well, but if the fluids are unusually cold or hot, they may be uncomfortable. Warm the fluids in a water bath to increase comfort. Ensure the fluids aren’t too hot by placing your wrist on the bag to check the temperature. Do not refrigerate them.
• As the fluids are running, a lump will form under the skin. Do not be alarmed; this pocket of fluid will be absorbed over the next few hours. If absorption is slow, gravity may cause the fluids to migrate downward along the side of the body. Fluids may even move under the skin of the front or rear legs in rare instances. Do not be alarmed. If this happens, the fluids will still be absorbed and your dog will not be in any pain or discomfort.
• You will not cause any problems if you inject a few bubbles of air under the skin. If quite a bit of air gets under the skin, you may feel a crackling sensation when you push on the skin, and your dog may experience mild discomfort for a couple of hours, but no real harm or damage will occur. The body will eventually absorb the air without difficulty.
• Use a creamy treat or baby food (no garlic/onion) to keep the dog’s focus away from what you are doing. Or, if your dog prefers cuddles, you or an assistant can rub them around their head and neck while you give the injection.
• Practice the procedure without a needle, but with the same rewards, to help your dog relax for the real thing.
• If your dog is sensitive to needles, ask your veterinarian if you can use a numbing cream.

What should I do if the fluid stops running during administration?

Fluid often stops running when the end of the needle moves against the skin or the underlying tissue. In this event, the needle opening is "blocked" or covered and fluid cannot flow freely. Do not remove the needle; instead, gently reposition it until the fluids begin to flow again. 

Experiment by slightly moving the needle's position (back and forth, up and down, side to side) until the fluids flow freely again. Twisting the needle (rotating clock- or counter-clockwise) will change the position of the bevel (the angle at the end of the needle). In most cases only a minor adjustment is all that is needed. You may have to reposition the needle several times during fluid administration.

What should I do if the fluid runs slowly out of the bag?

When you are finished giving fluids, you should close the lock firmly, but if you close it too firmly, it may crush the tubing so that fluid will not flow well on subsequent use. If this happens, move the lock to another place on the fluid tubing, and open the crushed area of the tube by pinching it open with your fingers. If you have a second person, you can squeeze the bag to increase the flow rate but stop if your dog appears uncomfortable.

What if the fluids become cloudy?

If any cloudiness or discoloration develops in the fluids, do not use the bag. This discoloration or cloudiness usually means that the fluids have become contaminated with bacteria. If you administer these fluids to your dog, a serious infection may occur under the skin.