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Euthanasia

By Debbie “The Rat Lady” Ducommun

(updated 5/13/13)

The lucky rats who live out their full life spans and then die in their sleep from old age probably do so from kidney or heart failure, or from a massive stroke. But what about rats who seem to be suffering as their lives come to an end? Fortunately, we have the option of euthanasia to help our rats achieve a peaceful death.

When is the right time to end a rat’s suffering with euthanasia? This is always a difficult and very personal decision. In my opinion, the time to help your rat die is when there is no hope of improvement through the use of medications or surgery, and he is no longer enjoying life. If his illness takes all his energy and concentration; if he shows no interest in food or physically can’t eat, even with help; if he seems to be constantly in pain, distress, or misery; or if he has episodes of respiratory distress that cannot be controlled with medication, this is the time to say goodbye and let your rat go on to a better place. Although it hurts, you know it’s the kindest thing to do as a last gift to a friend who has given you so much.

It is always most comforting for your rat if you hold or pet him as he gently falls unconscious. Most vet hospitals and animal shelters can euthanize animals, but you should first discuss the method they use for rats. If they won’t let you be present during the procedure, go somewhere else. When euthanasia is done correctly, there is no reason why you should not be present to comfort your rat.

If taking your rat to the vet or a shelter for euthanasia, consider taking along a roommate for comfort. After the euthanasia, I recommend letting the surviving roommates, or any other rats who interacted with the deceased, a chance to see the body so they know the rat died and didn’t just disappear. Most of the time, the survivors simply sniff the body all over and then go back to their regular routine. Occasionally, a rat will take longer to process the death and say good-bye to the body.

Methods of Euthanasia

Before discussing the methods I recommend, I want to list the methods that should not be used. According to the “AVMA Guidelines on Euthanasia,” published in June 2007 on the American Veterinary Medical Association website at www.avma.org, “Intramuscular, subcutaneous, intrathoracic, intrapulmonary, intrahepatic, intrarenal, intrasplenic, intrathecal, and other nonvascular injections are not acceptable methods of administering injectable euthanasia agents.” To translate this for the layman, this means that injections of euthanasia solution into the muscle, under the skin, inside the chest, inside the lungs, inside the liver, inside the kidney, inside the spleen, into the brain or spinal cord, or into any other tissue, is not acceptable. Injecting fluid into tissue or an organ is extremely painful.

Under no circumstances allow anyone to administer an intracardiac (IC; in the heart) injection to a conscious rat, even if the rat is sedated. Unfortunately, this euthanasia method is commonly used, but it is not humane. It is also illegal in California. The AVMA Guidelines on Euthanasia says, “Intracardiac injection is acceptable only when performed on heavily sedated, anesthetized, or comatose animals. It is not considered acceptable in awake animals, owing to the difficulty and unpredictability of performing the injection accurately.” This is because an injection into the heart is painful, and it’s also difficult to find the heart, sometimes taking several seconds or resulting in the solution accidentally being injected into the lungs. The intracardiac injection can be performed humanely only if the rat is anesthetized so deeply that he does not blink if the corner of the eye is touched. I guess some vets like to use IC because once the rat is injected, death is quick; but quicker is not always better!

Here is the euthanasia method I like to use as long as the rat is not in respiratory distress. First, give the rat diazepam orally or by SQ injection, either with a 1 cc tuberculin syringe with a 27-29 gauge needle or an insulin syringe. When a SQ injection is administered in the flank area, the rat rarely seems to feel it. Once the rat is sedated, an intraperitoneal injection (IP; in the abdomen) of the correct dose of sodium pentobarbital is administered, also with a 27-29 gauge needle or insulin syringe. This injection should be given in the lower right side of the abdomen in order to avoid causing pain by hitting the liver or any other organs. If the IP injection is administered correctly, it will cause almost no discomfort, because the liquid goes into the empty space of the abdominal cavity and not into any tissue. In fact, a rat will rarely even flinch if a small enough needle is used and the skin at the injection site is scratched with a fingernail first to distract the nerve endings. I also have given the IP injection of sodium pentobarbital without any sedation without it causing any obvious pain. The euthanasia solution will be slowly absorbed into the rat’s system and loss of consciousness will usually occur within 5-10 minutes, although it can take 15 minutes or longer for the heart to stop beating. This gives you the opportunity to hold, cuddle and talk to your rat as he gently slips away.

Many people prefer to euthanize their rats with a gas anesthetic; however, rats do not like breathing in the gas anesthetic. Also, you may not be able to hold and comfort your rat during the process. To euthanize in this way, the rat must either be placed in a small closed chamber, or a gas mask must be forced over his face. Do you want that to be the last thing he experiences? However, giving your rat his favorite treat might distract him enough so he doesn’t mind the gas in the chamber. Sedating the rat first also helps.

Consider asking the veterinarian to anesthetize your rat with the gas, inject the euthanasia solution in the abdomen while the rat is anesthetized, and then let the rat wake from the gas so the last thing your rat experiences is your cuddling him. If, however, a rat is experiencing respiratory distress, then euthanasia with gas anesthetic is the only recommended method because an abdominal injection is slower and can cause increased respiratory distress. Sedation can also increase respiratory distress and is not recommended for a rat in respiratory distress.

Recently, a rat owner said that her vet told her that using gas anesthesia to euthanize her rat would be too expensive, so did it instead with an injection to the heart. It seems that many vets have switched to using a new type of gas anesthesia, called sevoflurane, which is much more expensive than older types of gas anesthesia. However, older types of anesthesia, such as isoflurane, still work just fine for euthanasia, and are much less expensive. The cost for the amount to euthanize a rat is only about $2. So, if you want your vet to use gas anesthesia to euthanize your rats, ask your vet to order a bottle of isoflurane (about $45) to have on hand. If stored in a freezer, it will last at least a couple of years.

Home Euthanasia

The only humane way to euthanize a rat at home without veterinary help is with carbon dioxide (CO2). Euthanasia with CO2 is approved by the American Veterinary Medical Association (AVMA).

Concentrated CO2 is a central nervous system depressant and actually causes anesthesia. You know how you yawn when you’re sleepy? This is the body’s way of getting rid of excess carbon dioxide in your system which is making you sleepy. CO2 does not cause suffocation. The rat will be able to breathe normally, will become anesthetized and will then die.

The key to using CO2 humanely is its concentration. The normal concentration of CO2 in the air is only 0.038%. According to the 2000 Report of the AVMA Panel on Euthanasia, breathing concentrations of 7.5% increases the pain threshold, and concentrations of 30-40% cause anesthesia (unconsciousness) within 1-2 minutes. However, concentrations of 50% or higher irritate the eyes and respiratory tract and cause pain. Your goal is to create a concentration of 30-40% CO2 and hold it there until the rat is unconscious.

At first I used a cylinder of compressed CO2; however, with this method, the concentration of CO2 can easily get too high. (Using dry ice is not recommended because the CO2 amounts cannot be controlled and it also can cause severe burns.) Then I learned of a website written by Eric Lee of Maralee Rattery in St. David, AZ at www.alysion.org/euthanasia/ that tells how to euthanize mice by creating CO2 with baking soda and vinegar. This website also includes instructions for euthanizing small rodents for reptile food in a 1-gallon container.

The vinegar and baking soda method is quite simple and even better than using compressed CO2 because the concentration of the CO2 can be more precisely controlled. I have modified Eric’s method so it is suitable for rats. I have euthanized many rats with this method. If you want to test this method before using it, you can use a short candle to stand in for the rat. The CO2 will put out the candle.

Here is an email from rat owners who used this home method:

3/28/13

Dear Ms. Ducommun,
My husband and I only started adopting rats a couple years ago. When we started, your books were recommended to us and we read them with joy. We also came across several articles published by you, and in a way you have been a fairly constant presence to us as rat-caretakers. I wanted to send you a thank you because tonight you have once again been a huge help and comfort to us.

Recently, one of our rats, Tara, developed the signs of a pituitary tumor. I kept hoping that she would pass peacefully in her sleep, but she has always been energetic. I started to look for home methods of euthanasia, in order to be prepared for “the inevitable.” And the time came (earlier today) when we discovered that our sweet little girl could no longer walk or see. I had come across your article on at-home euthanasia. I was very skeptical at first, but when I saw that the method had been authored by you, I decided to trust it. I have a bachelor’s degree in chemistry so even though I didn’t have a 10-gallon aquarium, I knew I could do the math needed for the 12-gallon container that we have. I recalculated the ratios needed and my husband and I set about putting our rat to sleep.

I cannot tell you how strange it feels to be comforted by the manner of my pet’s death, but being able to sit and talk to her, watch over her, and see with my own eyes that she simply fell unconscious and slipped away—all while not having to add to her trauma AND our stress by taking her to a vet’s office—was more of a comfort than I could have possibly imagined. It was so hard to let her go, but the manner in which we put her to sleep was not part of that hardship.

My husband and I would like to thank you from the bottom of our hearts for helping us continue to be the best caretakers that we can. Thank you so much. Thank you.
Best wishes,
Colleen and Kyle Wilson

Warning: A few people have reported that their rats have reacted very badly to this method of euthanasia, but most have reported that the method worked well. Since posting this information, I have learned of research which shows that some rats appear to suffer a feeling of breathlessness with relatively low levels of CO2, while others seem to have no such feeling. Since you cannot anticipate which rats will experience this, perhaps it would help if you are able to give the rat a sedative before hand. If your rat does seem to experience respiratory distress during this method, you need to either remove the rat from the aquarium and end the euthanasia attempt, or try to add more CO2 as quickly as possible to shorten the time to unconsciousness.

PLEASE NOTE: These instructions require a 10-gallon aquarium or an airtight container of the same size to create the proper concentration of CO2. If you must use a container of a different size, you must adjust the amounts of vinegar and baking soda proportionately. The aquarium I use measures 10 inches X 20 inches X 12 inches tall (25.5 cm X 51 cm X 30.5 cm tall). One rat owner reported that a container only 8 inches tall (20.5 cm) did not work correctly. (10 gallons is about 38.6 liters.)

You will need a 10-gallon aquarium or a container of the same size in order to follow these instructions and to create the right concentration of CO2. You also need a small wire-and-plastic carrier, about 12" X 8" X 8", with the bottom pan no taller than 2". See the photo. (One rat owner reports that he successfully modified a Pet Pal carrier by drilling 6 holes in the walls, about 1.5" from the floor.)

You will also need:

2 containers containing 2 cups of white vinegar each (a cup is equal to 240 ml)

5 tablespoons of baking soda (make sure it is fresh!)

a heavy bath-sized towel

(If your rat weighs more than 1 ½ lbs., you need to use an additional 1 ½ tablespoons of baking soda and an additional cup of vinegar at the end.)

Set the aquarium where it will be comfortable for you to sit next to it, with your arm inside. Place the carrier in the center of the aquarium. Put a piece of soft cloth in the bottom of the carrier for your rat to sit on. The aquarium doesn’t need a lid because CO2 is heavier than air and will stay inside as long as there is no strong air movement. This means you can slowly put your hand down in the carrier to pet and comfort your rat during the process.

For the right CO2 concentration, you need to slowly create about 3 gallons of CO2 until the rat is unconscious, and a total of 5-6 gallons to cause death. Sprinkle 5 tablespoons of baking soda in the bottom of the aquarium around the carrier.

Place your rat in the carrier and give him a treat if you want. Pet and talk to your rat. While you pet your rat with one hand, slowly pour 2 cups of vinegar into the bottom of the aquarium with the other hand. The combination of the vinegar with the baking soda will cause fizzing. Pouring too fast can cause the foam to overflow into the carrier. The bubbles are the CO2 being created, but you won’t see any vapor. When the fizzing begins to slow down (about 1-2 minutes), pour out about half of the vinegar in the remaining cup into the aquarium.

Within 1-2 minutes your rat will become groggy, lie down, and go unconscious. The eyes will probably stay open because it requires muscles to keep them closed and at that point all the muscles are relaxed. Gently touch the inside corner of your rat’s eyelids to test if he is unconscious. A conscious rat will blink, but there will be no blink reflex when a rat is unconscious. An unconscious rat is not aware and cannot feel anything. You may see muscles twitch, but these are just reflexes and your rat is not aware of them. At the very end you may see your rat taking reflexive gasping breaths. Don’t let this upset you, it is just the body’s last ditch effort to breathe on its own because it is no longer getting any messages from the brain. It won’t last for long.

Once your rat is unconscious, pour out the rest of the vinegar and mix it well with the baking soda solution in the aquarium. Cover the aquarium with the towel so it won’t be disturbed and leave your rat there for at least 20 minutes. You can confirm death by feeling the chest for a heartbeat. The most reliable method to determine death, however, is to wait until the body stiffens.

There have been a few cases where people have followed these instructions, and the rat goes unconscious, but does not die. In most of these cases, it seems that the baking soda was not as fresh as it needs to be. When the people bought a new box of baking soda and tried again, it worked. If this method fails for you, you can contact me so we can try to figure out what went wrong, if you want to try again. Otherwise, you will need to find another method of euthanasia. Even if this method fails, it will not cause your rat any pain, and it is unlikely that a rat would experience brain damage if this method of euthanasia fails.

Rat Fan Club
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Chico, CA 95973
(530) 899-0605 ratlady@ratfanclub.org