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Surgery in Rats

By Debbie “The Rat Lady” Ducommun

There are several points about surgery on rats that are different from dogs and cats. Rat owners, be sure to discuss these with your vet before scheduling the first surgery.

1. Fasting rats overnight before surgery is not necessary and can be dangerous. Rats have a flap in their stomach that covers the esophagus and prevents both vomiting and burping. Rats do most of their eating at night and an overnight fast will deplete their energy reserves. Fasting can cause hypoglycemia and dehydration, which, along with hypothermia, can cause anesthetic complications and death.

When taking your rat to the hospital for surgery, make sure your rat has eaten something that morning, and the cage has food and water; it may be a while before the surgery. Food and water should be offered to the surgical patient as soon the rat awakens from the anesthetic at the hospital.

If the rat is going to have surgery on the intestines, a vet might request a fast to reduce the intestinal contents. Discuss this carefully with your vet. A liquid fast might be possible. Fasting longer than 2 hours is definitely not recommended for routine surgeries such as spays, neuters, and tumor removals.

2. It’s very important that rats be kept warm during and after surgery. General anesthesia prevents normal temperature regulation of the body and it can take several hours for normal temperature regulation to be restored. Rats are so small they lose body heat rapidly and if heat is not supplied, for instance by a heating pad, they can easily die from hypothermia. Not all vets realize this need for rats. Heat is not always supplied for cats and dogs undergoing surgery, although it probably should be; a study found that when heat was supplied for human surgical patients, they recovered more quickly and had fewer infections.

However, rats should never be placed directly on a heating pad. This can cause burns or heat stroke. The heating pad must be covered by one or more towels so the surface isn’t too hot.

3. A full course of an antibiotic to prevent infection is recommended, especially for neuters, major surgeries, for older rats, or if a rat has other health problems. If a rat who has previously had respiratory symptoms needs surgery, she should be put on antibiotics suitable for mycoplasma several days before the surgery to help protect her against a relapse during the stress of surgery. Continue giving the antibiotics at least until after the incision has healed.

4. Unless there are complications, you should be able to take your rat home the same day as the surgery. I do not recommend a rat spend the night at the hospital, and especially not if there will be no one to check on her. It’s best to schedule the surgery on a day when you will be home afterwards so you can keep an eye on the patient in case of bleeding or other problems. A rat may be sleepy from the anesthesia and analgesia that day, but should be back to normal the next day.

5. Once the patient is fully awake, and there are no complications, most rats should be put back with their cagemates for comfort and warmth. A rat will rarely bother the incision of another rat unless she is an obsessive groomer or barber.

6. Only inhalant anesthetics should be used for rats. This is so the level of anesthesia can be carefully controlled. Injectable anesthetics can be deadly since they cannot be precisely controlled.

7. A sedative/analgesic, often called a pre-anesthetic, should be given before the surgery only with CAUTION as the combination of the sedative and anesthetic can be fatal for rats! Acetaminophen can be given before the surgery. An analgesic/sedative such as butorphanol can be given as soon as the rat awakens from the anesthetic and is alert.

Not all vets give all their surgical patients analgesia, so discuss this with your vet. After a spay or neuter, the patient can experience severe abdominal cramping after the surgery and up to 3 days afterwards, so analgesia is essential for these surgeries. Tumor removals are less painful, but analgesia may help prevent rats from chewing out their sutures.

Tumor Surgery

8. Removing a small benign mammary tumor, up to the size of a walnut, is minor surgery, quick and easy. The incision only needs to be as long as the narrowest part of the tumor. After blunt dissection around the tumor, it can be popped out and then removed by more blunt dissection. This will keep the incision as small as possible. Often there isn’t even any need to tie off blood vessels as the tearing seals them. (I am appalled at the huge sums of money some vets are now charging to do these surgeries. Most of these surgeries take no more than a half an hour, often much less.)

Even larger tumors, up to the size of a large egg are usually simple to remove. Larger tumors often have several blood vessels that need to be tied off. Any excess skin must be removed, as loose skin remaining after the surgery usually results in a seroma (an accumulaton of fluid). If a small seroma develops, the body should eventually reabsorb the fluid. A large seroma may require another surgery to remove the excess skin.

Removing a very large tumor is more risky but can be done. The main danger is shock due to the loss of blood and body fluids contained in the tumor. I use homeopathic remedies to combat this problem, and have successfully removed several large and risky tumors. If you are interested in learning more about this, please contact me. It is also possible to administer IV fluids to rats during surgery using a very small needle in the femoral vein.

Spays

9. A rat spay is similar to a cat spay and should cost about the same. If the surgeon is experienced, complications are rare, although there is always a small risk. I believe the risk of bleeding from the ovarian artery is low because of its small size.

It is most practical to remove the ovaries and as much of the uterine horns as can be reached with a small incision. It is not necessary to remove the whole uterus as uterine cancer is rare in rats.

When scheduling a rat to be spayed, it’s best to do it 2-3 days after she is in heat. When in heat, the uterus is blood engorged, and although a spay can be done at this time, it’s best done when the rat is not in heat. A pregnant rat can also be spayed, but occasionally a pregnancy (or false pregnancy) will change a rat’s behavior and make her aggressive or obsessive. If this happens, this change may persist after the surgery, so in this case it’s better not to spay while she is pregnant.

Neuters

10. Neutering is easier on both surgeon and rat when done as young as possible, even at 4 weeks. Although a neuter can be done at any age, I don’t like doing it on rats over 18 months of age because an elective surgery is more risky on an older rat. A neutered male may continue to be fertile for 3 weeks after the surgery.

Neutering a male rat is a little more complicated than neutering a dog or cat. A rat neuter also seems to cause more pain than a rat spay. The testicles move freely between the scrotum and the abdominal cavity so a rat neuter should be done using a closed method and sterile surgery to prevent peritonitis. The scrotal sac should be sutured or ligated separately from the skin. The incision should be made at the distal end of the scrotum, not near the penis, because if an abscess occurs it can be more serious near the penis, while distal abscesses tend to be benign.

An abscess is a common complication after a neuter. It is usually a sterile abscess due to a reaction to the sutures, not an infection. This usually occurs about 2-6 weeks after the surgery while an infection will usually occur within a few days. Once the abscess opens and drains it usually heals up quickly. (See Abscesses.)

The Incision

11. When the incision will be small, as for a spay, subcuticular sutures may be used. This technique hides the sutures within the incision and it is very rare for a rat to chew them out. However, for larger incisions which need more sutures, such as for large tumors, rats often have an inflammatory reaction to the absorbable sutures. Plus it takes too long to put them in.

Large incisions should be closed with staples, or Michel wound clips (my choice, as I find the belly skin of rats tends to be too thin for staples, and the width of the clips means I can use fewer of them.) Staples and clips resist casual exploration by the rat, but can be removed with minimal skin damage by a persistent rat. In some cases, surgical glue can be used but rats often tear the glue open. Steel wire sutures are more resistant to being chewed out, however if a rat wants to remove them, she will, even if she has to tear the skin to do so.

You can wait at least 3 weeks to have staples or clips removed as the longer you wait, the easier they are to remove. Staples or clips can usually be left for a long period without any harm. However, a Michel wound clip can sometimes rotate, exposing points that can snag fabric. Then it must be removed like a fishhook, clipping off one end, then extracting it.

Owners should check the incision daily for any problems. Normal healing can cause some swelling and redness, but pus, drainage, greenish skin, or a bad smell indicate an infection and you must contact your vet immediately.

Protecting the Incision

12. Some rats, especially females, will try to chew out their sutures. The most effective methods to protect an incision are with a body cast or a cervical collar. However, I do not recommend the routine use of these methods for every surgery. These restraints can be quite upsetting for the rat so they should only be used if the patient has a history of chewing her incisions open, has actually chewed open an incision longer than 2", or if the incision is longer than 2" and the owner would have trouble getting back to the hospital to have an opened incision re-closed. An open incision 2" long or less can be left open because it will quickly heal on its own, even if the skin gapes open.

An Elizabethan collar, commonly used in dogs and cats, should ONLY be used in rats to prevent scratching of the eye or ear in life-threatening situations. It should not be used to protect a body incision because it prevents grooming, and can also prevent eating, drinking, and walking.

Rats who chew open their incision usually do so the first night after the surgery, so it’s especially important to check the incision the next morning. An incision open more than 2" should be reclosed. This can be done easily with staples, Michel wound clips, or surgical glue without the need for anesthetic or sedation. Putting in staples or clips is quick and only causes minor discomfort. If you can’t get back to the hospital you can close a large open incision yourself with Super Glue (see Treating Injuries in Nursing).

Even if an incision is protected in some way, some rats are masters at chewing open their incision no matter what. For this reason, I recommend that all post-surgical rats be kept in a cage with only shredded paper or fabric—no litter or bedding with small particles—until the incision is healed to prevent possible contamination.

The Body Cast

A body cast works by preventing the rat from bending over to reach the incision. The body cast may also directly protect the incision, but it must still prevent the rat from bending. If the rat can reach the cast with her teeth she will be able to chew it off. The body cast is more effective than the cervical collar and should be used if the incision is in the lower abdomen or groin area, but it is also much more restrictive than the cervical collar. The rat will still be able to walk but won’t be able to sit up. If the incision is under the armpit or on the shoulders you can use a cervical collar.

Adhesive bandage tape makes the most secure and comfortable body cast. Rats can easily wiggle out of a stretchy bandage unless it is wrapped over the shoulders and between the arms, and this actually restricts the rat’s movement more than the adhesive tape.

If the incision will be covered by the wrap, cover it with gauze. Wrap several layers of ¾" or 1" adhesive tape around the rat’s middle, between the front and back legs, sticking the tape directly to the fur, otherwise they just walk right out of it. The cast should not restrict the rat’s breathing, but it must be snug enough so the rat won’t get her back feet caught in it. Apply 3-5 layers of tape to make the cast stiff.

The cast will last at least 2 to 5 days, long enough to protect the incision during the critical healing period. When the incision is mostly healed, if your rat hasn’t gotten out of the cast herself, you can remove it by cutting the tape and putting vegetable oil on the inside to help dissolve the adhesive.

The Cervical Collar

A cervical collar is not as effective as a body cast, but it is less restrictive. It prevents the rat from bending her neck to reach an incision in the armpit, or on the shoulder or back area. Simply wrap enough layers of ½" adhesive tape snugly around the rat’s neck to make a collar stiff enough to prevent the rat from bending her neck.

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