by Debbie “The Rat Lady” Ducommun
updated
This article is from my booklet Rat Health Care. I highly recommend you order a copy to have on hand. Check it out at Rat Books
Respiratory disease is the most common health problem and cause of death in pet rats. The most common organism causing this disease in rats is the bacteria Mycoplasma pulmonis. Mycoplasma is very contagious and incurable. There are different strains of mycoplasma that are more or less virulent and so can cause more or less severe disease. Different rats also seem to have differing resistance to the disease. The severity of a mycoplasma infection can be increased by cigarette smoke, ammonia from a dirty cage, vitamin A or E deficiency, pine or cedar shavings, and a concurrent respiratory infection of another type, as well as genetic susceptibility.
A mycoplasma infection makes a rat more susceptible to secondary respiratory bacterial infections as well. The respiratory symptoms that are common in rats can be caused either by the primary mycoplasma infection, secondary infections, or both as well as heart disease. In young rats, symptoms are more likely to be caused by secondary infection, so they need to be treated accordingly.
Most respiratory symptoms in rats are caused by respiratory infections or heart disease. It is very rare to find a lung tumor in rats. Since 1985 years I have done gross autopsies on more than 200 rats and I have only seen two lung tumors.
Mycoplasma typically causes a “blister” effect on the surface of the lungs, lung abscesses, and emphysema. It also causes inflammation and infection of the uterus. To see autopsy pictures of rat lungs click here.
There is a special blood test, called a serology ELISA test, that can detect mycoplasma. (However, the disease is so common, you should just assume your rats have it.) Charles River Labs, 1-800-LABRATS, will perform serology testing on rat blood. The myco test is $11.75.
Common Symptoms
Often, the first symptoms of respiratory disease seen in a rat, especially in
young rats, will be caused by a secondary infection. For any symptoms, I recommend first
trying an antibiotic that works well for secondary infections. Secondary infections can become more
serious more quickly than mycoplasma, so treat for them first. If you treat for mycoplasma first, and
it turns out to be a secondary infection, the rat may get so sick he dies
before you can try the treatment for secondary infections. Usually a mycoplasma infection is
chronic, that is, it starts out slowly with mild symptoms that gradually get
worse over a period of weeks or months, so quick treatment is not as critical
as it is for a secondary infection.
In my experience, amoxicillin tends to work best for secondary infections. If the symptoms do not improve within 3 days of treatment, then you should switch to another antibiotic, probably one that is good for mycoplasma. The first symptom of mycoplasmosis is usually frequent sneezing (healthy rats rarely sneeze), but then this often goes away and there can be a long period of time without symptoms. However, mycoplasma can cause lung damage even if there haven’t been any overt symptoms. (For how to mix and use amoxicillin see “Giving Medications” and “Mixing Medications in a Liquid” below.)
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Concerning amoxicillin and veterininarians: Many vets don’t want to use amoxicillin on rats. This is probably because in vet school they learn that amoxicillin can’t be used in guinea pigs, rabbits or hamsters (because it kills the good bacteria in their intestines), and they probably generalize this to rats and mice. However, rats and mice usually tolerate amoxicillin quite well. In my experience only a very small percentage of them will get diarrhea from it, and this is not life-threatening; it will usually clear up with a probiotic, or the amoxicillin can be stopped.
Here are some references for using amoxicillin in rats for your vet to check if they are reluctant to prescribe amoxicillin:
Exotic Animal Formulary, Third Edition, James W. Carpenter, MS, DVM
editor, Elsevier Saunders Publishing
Page 377, Antimicrobial and antifungal agents used in rodents.
Ampicillin for mice and rats: dosage 20-50 mg/kg
(Note: ampicillin and amoxicillin have essentially the same adverse reactions and effectiveness, so they can be used interchangeably)
ViN (Veterinary
Information Network, Inc.) Website
Thomas Donnelly, BVSc on
Johanna Briscoe, VMD, on 07/08/2004 “I have used Clavamox liquid in a
rat and it worked beautifully on an abscess that I thought may have been from a
bite…. Clavamox dose same as
in other mammals—13.75 mg/kg
(Note: Clavamox is the brand name for a mixture of amoxicillin and clavulanic acid.)
Elizabeth Mitchell on
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A respiratory infection, whether caused by mycoplasma or a secondary infection or both, can begin in the upper respiratory passages and then progress into the lungs causing pneumonia, or it cause pneumonia right away. It can invade the inner ear and affect balance, causing a head tilt which can progress to rolling behavior. An infection can also cause damage to the nasal cavity and nasal bones resulting in fatal bleeding. Any noise made while breathing can be a symptom of an infection and/or heart disease.
Because mycoplasma is a chronic, progressive, incurable disease, older rats tend to have more problem with respiratory problems, but even symptoms in older rats can be caused by a secondary infection, and not mycoplasma itself. If a rat’s immunity is weakened due to stress, old age, or another disease, they can be more susceptible to secondary infections.
Without treatment, mycoplasma and secondary infections will usually cause major lung damage and in most cases the rat will eventually exhibit labored breathing. The heart may also be damaged. The rat may lose weight as his poor respiration makes it hard to eat or heart disease causes lack of appetite. The toes and tail tip may turn blue from lack of oxygen. The rat may experience respiratory distress, which causes a rat to gasp through her mouth, or dash about in panic when she can't get enough air. If treatment cannot prevent such attacks, euthanasia is the kindest action.
A rat infected with mycoplasma is usually active and eats normally until the disease is quite advanced. If a rat has a rapid onset of symptoms such as loss of appetite, lethargy, rough coat, hunched posture, runny eyes and nose, and difficulty breathing, these are symptoms of an acute secondary bacterial infection, not mycoplasma. Immediate antibiotic treatment, preferably with amoxicillin, or amoxicillin together with Baytril, will be necessary to save a rat this ill. A rat that is extremely lethargic and refuses to eat or drink must have the antibiotics force fed 0.1 ml at a time. Gentamicin with one of the penicillins can also be used.
A number of secondary bacteria can be associated with mycoplasma infections including the Cilia-Associated Respiratory (CAR) bacillus, Pasteurella pneumotropica, and Corynebacterium kutsheri. Another common bacteria that can cause respiratory disease in rats is Streptococcus pneumoniae. This is not the same organism that causes strep throat in humans (which is Streptococcus pyogenes) however, there have been some suspicious cases that suggest that rats might be able to get a strep infection from a person with strep throat, so people with strep throat should stay away from rats, and rats in the same house should be watched carefully for strep symptoms. Strep infections in rats are usually fatal within three days without vigorous antibiotic treatment. Rats cannot get human colds or flu.
Viral Infections
There are also two viruses that can cause respiratory symptoms in rats. Sendai
virus causes sneezing and sometimes a stuffy nose, especially in babies which
can prevent nursing and cause death. Sialodacryoadenitis (SDA) virus (also
called rat corona virus) is an infection of the salivary glands, and symptoms
can include any of the following: sneezing, runny eyes and nose, swelling under
the throat, and bulging eyes. Treatment with ophthalamic ointment may be
necessary to prevent permanent eye damage.
In lab rats, which are all mycoplasma-free, these viruses are not usually fatal to post-weaning rats and the rats recover in a week or two. Both viruses will die out in a population if breeding and new introductions are discontinued for at least two months. However, if a rat is already infected with mycoplasma, which most pet rats are these days, a viral infection on top of it makes the rat extremely susceptible to dangerous secondary infections. Aggressive antibiotic treatment for secondary bacterial infections will be necessary. Either amoxicillin together with Baytril, or gentomicin with one of the penicillins is recommended. Supportive therapy, including fluids, may also be necessary. An injection of dexamethasone or dexamethasone sodium phosphate at 1 mg/lb can be extremely helpful in reducing the inflammation of the glands and respiratory tract and ease the symptoms.
Most rat respiratory diseases, especially mycoplasma and the viruses, are infectious and can be spread both through direct contact (rat to rat) and through the air. Viruses can also be transmitted on hands, clothing, and other inanimate objects. Mycoplasma is not known to be transmitted in this way. To protect your rats from the viruses, it is always a good idea for new rats or rats returning from a show to be quarantined for at least 2 weeks before exposing them to your other rats. Ideally there should be no air-flow between your rats' room and the quarantine area. Wash thoroughly and change your clothes after being with the quarantined rats.
(None of the organisms causing respiratory infections in rats are infectious to humans. The only disease I know of that can be transmitted from domestic rats to humans is “rat-bite fever,” a rare bacterial infection similar to cat-scratch fever. Symptoms can occur several weeks after a bite and include a rash and flu-like symptoms. I have personally heard of only 2 cases. You can find out more about rat-bite fever at ratfanclub.org/ratbitefever.html )
Antibiotic Treatment
Although mycoplasmosis in rats is basically incurable, treatment with
antibiotics can help control the damage. Antibiotics are also vital in treating
secondary bacterial infections.
A head tilt caused by an inner ear infection requires early and aggressive treatment if the symptoms are to be reversed. Since this can also be caused by a secondary bacterial infection, Baytril, chloramphenicol, or gentamicin (always with a penicillin antibiotic) which tend to be effective against most other bacteria as well as mycoplasma, are recommended. Treatment with an anti-inflammatory such as prednisone at 1 mg/lb twice a day or ibuprofen at 15-60 mg/lb 2 to 4 times a day, along with the antibiotics, is also vital to help reduce inflammation in the inner ear.
Another NSAID that can be use for inflammation in rat is Metacam. Metacam is a brand name and the generic name is meloxicam. The liquid sold by vets is for dogs, and since dogs do not metabolize NSAIDs well, the dog dose is very low (only 0.1 mg/lb). Rats metabolize NSAIDs very well. (That’s why the dose of ibuprofen for inflammation in rats is 15-60 mg/lb 2 to 4 times a day.) By comparing the human dose of ibuprofen to that for rats, and then looking at the human dose of meloxicam (which is 7.5 to 15 mg a day), it appears that the best dose of Metacam for rats is 1 to 2.25 mg/lb. Since the usual concentration of the Metacam liquid is 1.5 mg/ml, a 1-lb rat would need 0.6 to 1.5 ml. In addition, although meloxicam is only given once a day to humans and dogs, because the rat’s metabolism is so much higher, it might need to be given more often to rats. I recently talked with a rat owner giving Metacam to a rat with severe pain, and she reports that once a day does not seem often enough.
A head tilt can also be caused by a pituitary tumor or stroke, and in this case the primary treatment is with steroids. But an antibiotic should also be given since steroids depress the immune system, and can also help shrink a tumor.
In my experience, the best antibiotics to use against mycoplasma are doxycycline and/or Baytril. These antibiotics can be ordered for birds from Jedd’s Pigeon Supplies (see sources below). For information about mixing and using doxycycline see “Mixing Medications into Liquid” below.
Amoxicillin is available as fish capsules in some pet shops and feed stores and by mail order from Jedd’s Pigeon Supplies or Doctors Fosters & Smith (see sources below). Amoxicillin is recommended for an acute infection, a secondary infection, or a possible strep infection. For information about mixing and using amoxicillin see “Mixing Medications into Liquid” below. Other antibiotics that have been successful at treating some secondary infections are trimethoprim-sulpha, cefadroxil, and chloramphenicol.
If a particular antibiotic is effective against the infectious organism, you should see an improvement in acute symptoms within 2-3 days, or in chronic symptoms within a week. If you don’t see any improvement within this time, you must try a different antibiotic. When treating a secondary respiratory infection, antibiotics should be continued for at least 2 weeks, or at least a week after all the symptoms disappear to prevent an immediate relapse. Treatment should be reinstated if the symptoms come back. If one antibiotic is no longer effective, try another one.
When treating mycoplasma, the minimum length of treatment should be 3 weeks, and 5-6 weeks is probably better in most cases. For some rats, those that have frequent reoccurances of symptoms, it is best to continue treatment for several months, or maybe even the rest of the rat’s life. Remember, mycoplasma is incurable and must be treated aggressively and persistently. Doxycycline and Baytril can be used for long periods of time without any ill effects in most rats.
Other Prescription Drugs
Two prescription drugs that can be very helpful in rats with advanced
respiratory disease are aminophylline, which is a broncodialator, and and
predisone, which reduces inflammation.
Non-steroidal anti-inflammatories, such as ibuprofen, can be helpful in
some cases also. The dose for
aminophylline is 1.36mg/lb twice a day. The dose for prednisone is 1 mg/lb
twice a day. Both can be given either orally or by injection. Primatene (ephedrine) is a bronchodialator
available over the counter. You can
buy an inhaler to have on hand for emergency treatment of respiratory distress.
(See page 2.) You can also try the
oral form of Primatene at 1 mg/lb twice a day.
The dose for ibuprofen is 15-60 mg/lb 2 to 4 times a day. You can use you can either crush up a tablet or use liquid baby medications if they do not contain sorbitol, an artificial sweetener that rats hate. Sorbitol will be listed under the inactive ingredients. Most rats like berry flavored Motrin. To figure out the dose, look on the bottle to see how many mg/ml. Figure out how many ml to use to give your rat the proper number of mg. It’s a good idea to give the rat a treat afterwards to mask the bad aftertaste that may cause your rat to refuse the medication the second time.
For tablets, you can grind them up into a fine powder on a small plate with a spoon. You can then mix the powder in liquid or food. Some suggestions include baby food, pudding, mashed avocado, yogurt, brown sugar and carob powder, honey, peanutbutter mixed with jelly, moistened graham cracker, non-fat cream cheese, margarine, Nutri-Cal, pasta sauce, and as a last resort, ice cream, frosting, cheesecake, or even butterscotch or chocolate syrup! Use only enough food to mask the taste of the medicine so your rat will eat it all immediately. Adding a bit of salt will help counter the bitter flavor of medicines. For sweet foods you can also add some Equal to make them even sweeter. If your rat refuses to eat the doctored food voluntarily, those in paste form can be smeared on his mouth, or even on the backs of his ears so he will groom the paste off and eat it.
If the lungs are congested, a diuretic (to reduce fluid in the lungs) is called for. I’ve had good results with Lasix at a dose of 1-2 mg/lb 1-3 times/day. When a rat is on a diuretic, you must frequently check him for dehydration by pinching the skin on his back. In a rat who is normally hydrated, the skin will snap back immediately. The longer the skin takes to snap back, the more dehydrated a rat is. If a rat on a diuretic becomes dehydrated you must stop the diuretic and get the rat rehydrated.
I have found that rats with advanced respiratory disease often have heart disease as well. The recommended treatment for heart failure is a low sodium diet, enalapril (dose 0.25 mg/lb twice a day), which lowers the blood pressure and makes it easier for the heart to beat, and atenolol (1 mg/lb twice a day), an beta-blocker that slows the heartbeat to make it more effective. (The American Heart Association recently announced it was recommending the use of beta-blockers for most patients with congestive heart failure.) Enalapril is so safe it can be used as a diagnostic tool. If giving enalapril makes the rat feel better, then you know he has congestive heart failure. If enalapril is going to help you should see improvement in the rat’s symptoms within 5 days. A diuretic can also help in some cases.
If the symptoms include skin edema or if it can be determined by x-ray that the heart is dilated, rather than hypertrophic, digoxin, which helps the heart beat more strongly, can be added to the treatment. The dose for digoxin is 0.001-0.0025 mg/lb twice a day. As time goes on, you often have to increase the dose. I have had two rats with congestive heart failure live to 38 months with digoxin, enalapril and atenolol treatment!
Studies have also found that some supplements can help people with congestive heart failure. These include the omega-3 oils in flax oil (25 mg/day), co-enzyme Q10 (10-30 mg/day), L-carnitine (25 mg/day), and taurine (50 mg/day). The doses I've recommended here for rats are 1/10 the human doses. I have been giving these to 5 of my rats with good results. They take them eagerly in peanut butter balls.
Other Treatments
If the air in your home is dry, a humidifier will help your rats breathe more
easily. If your rat’s nose seems congested, the decongestant
pseudephedrine might help clear the breathing passages. Buy the non-drowsy
pediatric formula. The best dose is unknown. Try 1.5 mg twice a day. The
antihistamine chlorpheniramine maleate may also be beneficial. Try giving 0.2
mg/lb twice a day.
Another medication which can help is called VetRx. It is also available at Petco as FerretRx. It works by stimulating deeper breathing and contains Canada balsam, camphor, oil origanum, and oil Rosemary. The best results seem to come by putting a few drops in the nest box or on the bedding 2-3 times a day where it will be inhaled. You can also rub it on your rat’s nose, but this seems to cause discomfort for some rats. When using it, try alternating one week on, one week off. It seems to cause irritation if used continuously. You can order a 2 oz. bottle (which lasts a long time) from Karen at (201) 227-1272.
If a rat is having gasping attacks, he may swallow large quantities of air which he can’t burp up. This will cause stomach distension and discomfort. To help the air pass through the digestive tract, you can try using the product Gas-X. Try giving about 1/4 teaspoon.
The homeopathic remedy antinonium tartaricun might be of some help. It can be used in conjunction with antibiotics and other medications. Other herbal and homeopathic remedies, as well as acupuncture may be of benefit to rats with mycoplasma. We are just beginning to explore the possibilities. Please let me know what experiences you have!
Even if your rat becomes very sick, don’t give up. I know of several rats pulled back from the brink of death after receiving antibiotics, recovering their health to live for several more months. Although respiratory and heart disease are extremely common in rats and can be devastating, prompt, persistant and aggressive treatment can help keep the diseases in check in most cases, and will usually allow your rat to enjoy a fairly normal life.
Using Antibiotics
Antibiotics must be selected carefully not only according to the type of bacteria
causing the infection, but also how the antibiotic works, what tissues of the
body it can penetrate, the patient’s state of health, and any possible
side-effects. For instance, the penicillins and sulphonamides can cause
allergic reactions in sensitive individuals, and tylosin and amoxicillin
sometimes cause diarrhea.
Whenever using antibiotics there is also the possibility that some of the bacteria will be resistant. Once the susceptible bacteria have been killed off, resistant bacteria can flourish. Then a different antibiotic must be used. In some cases it may be necessary to use two antibiotics at once to eliminate this problem.
Antibiotics are divided into two groups according to how they work. Bactericidal antibiotics actually kill the bacteria, but they only kill growing bacteria. Bacteriostatic antibiotics prevent the bacteria from growing, so the immune system can kill them off. A bacteriostatic antibiotic can interfere with the action of a bacteriocidal antibiotic and so in most cases the two groups of antibiotics should not be used together. Because bacteriocidal types actually kill the bacteria, they should be used for serious acute infections when possible.
In general, the length of treatment for infections affecting the skin should be about 7-10 days. Respiratory and urinary infections generally need to be treated for several weeks. An exception to this is gentamicin which should never be used longer than 14 days.
Amoxicillin, amoxicillin with clavulanate, and cefadroxil are fairly safe for use in pregnant animals, but most other antibiotics will pass through the placenta into the developing fetuses and are not recommended for use during pregnancy. However, you may have to use another antibiotic to save the mother’s life.
Giving Medications
One of the trickiest parts of medicating rats is getting the medicine inside
them! Oral medications can be administered to rats in four forms: liquid,
paste, chewable, or in the drinking water. If tablets or capsules are
prescribed, the only way to get the medicine down your rat is to mix it in one
of these forms.
For tablets, you can grind them up into a fine powder on a small plate with a spoon, or let them soften in a liquid. For capsules, pull the halves of the capsule apart and dump out the powder. You can then mix them in liquid or food. To mix in food, mix the powder well and divide into little piles, each containing the proper dose. Then you can scrape a pile into the food.
You can mix medications in foods such as baby food, mashed avocado, pasta sauce, margarine, butterscotch syrup, brown sugar and carob powder, graham crackers and Kool-Aid, Nutri-Cal, and even as a last resort, frosting or chocolate syrup. Antibiotics other than tetracycline can be mixed in yogurt, pudding, non-fat cream cheese, or ice cream.
Use only enough food to mask the taste of the medicine so your rat will eat it all immediately. Adding a bit of salt will help counter bitterness. If your rat refuses to eat the doctored food, you can mix it in a dab of margarine and smear it on the back of his ear. Most rats will clean the margarine off their ear and eat it, no matter how bad it tastes.
You can also mix either powders or liquids in liquids such as Hawaiian Punch Concentrate, VAL syrup (ask your vet), or strawberry sundae syrup. Liquid medications are easy to give if they taste good to your rat. Just place a drop in the side of his mouth with an eyedropper or syringe (without a needle) and he’ll probably start to lick it right from the tip. However, if a rat dislikes the taste (or the aftertaste) of a liquid, it can be impossible to get it down, because he’ll simply refuse to swallow. (For how to mix a medication in liquid see below.)
Powders can also be mixed into my famous peanut butter balls. To make 20 doses, mix 1/2 tablespoon smooth peanut butter with 20 doses of the medication. Add 1/2 teaspoon sugar (more if the medication is very bitter) and enough flour to form a stiff dough and mix well. Roll into a snake on wax paper and cut into20 equal pieces. Form each piece into a ball and roll in flour and keep in the refrigerator. You can also use non-fat cream cheese instead of peanut butter. Most rats love these balls, but try making just one first before mixing up a whole recipe and possibly wasting the medication.
If you have to medicate a rat who looks similar to another rat, you can use a non-toxic felt pen to mark one of the rats on his fur or the base of the tail. Or, if they have dark fur, you can try using peroxide to make a lighter mark on one of them.
Mixing a
Medication into Liquid
To mix a tablet or capsule into a liquid, you will need a 1 ml syringe
or insulin syringe to measure out the doses. Insulin syringes are marked in units,
with 10 units equaling 0.1 ml. A
film canister is a good size to mix a liquid medication in.
Grind the tablet or capsule contents to a powder (if it isn’t
already a powder). Or, if you can
make the medication ahead of time, you can put a tablet or contents of a
capsule into the liquid to soak for 12 hours, and then just stir it. To figure out the amount of liquid to
use, take the number of doses in the powder and multiply it by the liquid dose
you decided on.
A 250 mg capsule of amoxicillin contains 25 1-lb. doses. Mix one 250 mg amoxicillin capsule into
7.5 ml of flavouring (such as soy milk, non-dairy creamer, slightly diluted
strawberry syrup). The dose for a
1-lb. rat is 0.3 ml, for a 1¼-lb rat is 0.5 ml, and for a ½-lb
rat is 0.15 ml.
A 100 mg capsule of doxycycline contains 40 1-lb doses. Mix one 100 mg capsule into 12 ml of
slightly diluted strawberry syrup (or other syrup—do not use products
that contain calcium).
For other medications, first you need to figure out how many doses
there are in the tablet or capsule.
To do this, divide the strength of the tablet or capsule by the required
dose. For example, if a capsule
contains 250 mg and the dose is 10 mg/lb (like with amoxicillin capsules), you
divide 250 by 10, and you find that the capsule contains 25 doses for the
average 1-lb rat.
Then you must decide what liquid volume dose you want to give. For a medication that might taste bad, I
recommend making the dose 0.1 ml.
For medications that you know your rats will like, you can make the dose
0.3 ml. Multiply the dose volume by
the number of doses in the tablet or capsule. For instance, if there are 10 doses in a
tablet, 10 X 0.3 = 3 ml of flavoring.
Putting Medications
in the Drinking Water
Some medicines, like tetracycline and tylosin, can be added to the drinking water. This can be a handy way to give medicine to a large number of rats, but it’s much better to dose individual rats with medications in food. They are more likely to get the correct dose this way and you won’t be dosing cagemates who don’t need the medication.
When putting medications in the drinking water there are some special precautions. If the medicine tastes bad, some rats refuse to drink, resulting in both no medication ingested and dehydration. Adding the medication to a flavored drink will sometimes solve this problem. Light will destroy tetracycline, so cover the water bottle with a tin can, aluminum foil, or a dark sock. You can put tylosin in apple juice, Tang, Hawaiian Punch or Kool-Aid. However, do not use Tang for tetracycline. Calcium and magnesium, present in this drink, can bind to the tetracycline and deactivate it. For the same reason it's a good idea to use distilled water (available in grocery stores) for tetracycline because some tap water also contains calcium and magnesium. You should also avoid giving dairy products within 2 hours of tetracycline.
Medications in the water must be mixed up fresh and replaced often, so don’t make up too much at one time. Rats only drink about 1-2 oz. per day. In hot weather, keep most of the mixture in the refrigerator to prevent fermentation, and replenish the water bottle 2-3 times a day.
Special Warnings
Tetracycline should not be given to pregnant rats because it can be toxic to
the liver and interfere with bone and tooth development in the fetuses.
The kidney toxicity that gentamicin sometimes causes in other animals is not a big problem in rats, but it is still a good idea to encourage the patient to drink plenty of water by offering sugar water or juice to drink. Gentamicin can’t be given orally because it can’t be absorbed so it must be injected. Or, another method of giving gentamicin is with a nebulizer which creates tiny droplets which can be inhaled into the lungs. The antibiotic is mixed in a 10% saline solution and administered for 15 minutes twice daily. Baytril can also be nebulized.
Baytril should be given by injection only when absolutely necessary as it is extremely caustic and can cause severe skin ulcers which take a long time to heal. I know of 2 rats who bled to death after scratching the ulcers caused by Baytril injections. Diluting the Baytril 30:1 with sterile saline might help prevent this. It should be given by subQ injection only and never in the muscle.
Sources for Antibiotics
Some antibiotics are available over the counter at pet stores, feed stores, or
from mail order catalogs. For some, look in the aquarium section for fish
capsules. Others are available only by prescription either from your vet, a
pharmacy, or a mail order catalog. Here are some sources:
Omaha Vaccine Company, 800-367-4444 (tylosin soluble, tetracycline)
Jeffers, 800-JEFFERS (gentamicin)
Doctors Fosters & Smith, 800-826-7206, www.drsfostersmith.com , amoxicillin
fish capsules, item # item #CD-18876.
(Please note that they sometimes change the item number, so just search
for amoxicillin in the fish department.)
Jedd’s Pigeon Supplies, Call on the phone 800-659-5928 and ask for Greg. They have doxycycline capsules (be sure to ask for capsules), amoxicillin capsules, 10% liquid Baytril (ask for Enroxil which is generic 10% Baytril really cheap—1000 rat doses for only $40 plus shipping!)
A List of Antibiotics
All medications to be given orally unless otherwise stated. SID=once daily; BID=twice daily; TID=3X a day; SQ=subcutaneous injection
Bactericidal Antibiotics
amoxicillin—Penicillin family. Broad spectrum. Recommended for secondary respiratory
infections, good for urinary infections and preventing infection after injury
or surgery. Can cause allergic reactions.
Don’t use with atenolol.
Dose: 10-50 mg/lb BID. Brand: Amoxi-drops. Tastes good.
amoxicillin with clavulanate—More broad spectrum than amoxicillin. Good for skin infections and abscesses. Can cause allergic reactions. Dose: 10 mg/lb BID. Brand: Clavamox Drops. Also tasty and easy to give.
ampicillin—Same family as amoxicillin but not absorbed as well. Give 20 mg/lb BID. Use and precautions are the same. Available as aquarium capsules.
cefadroxil—Broad spectrum. Same family as amoxicillin, but a little stronger. Dose: 10 mg/lb BID. Brand: Cefa-drops. A tasty orange flavored liquid.
enrofloxacin (Baytril)—Can be very effective against
Mycoplasma. Good for skin, intestinal, and urinary infections. Best not to use
in growing animals (might stunt growth) but if other antibiotics aren’t
working you can use Baytril. Can be used long term. Dose: 10 mg/lb BID orally or SQ. For the 10% liquid the dose is 0.1 ml/lb
BID. Injections can cause skin
ulcers. The injectable liquid, the 10% oral liquid, or ground tablets can be
mixed with soy baby formula or Ensure and given orally. Tastes bad. I’ve
had the best luck giving the 10% liquid mixed in 4-6 ml of a product such as
strawberry Ensure or Boost in a baby food jar lid, or in 1/8 teaspoon of the
soy baby formula powder, making a paste.
It helps if you put the baby food jar lid on a small magnet to help keep
your rat from tipping it over. It is best if you
mix the liquid 10% Baytril up only as you use it and not ahead of time. DO NOT
refrigerate the 10% liquid Baytril or it will crystallize.
gentamicin—Broad spectrum. Must be given by injection. Good for serious systemic, respiratory, and urinary infections. Effective against Mycoplasma. Best used along with amoxicillin or cefadroxil. Can impair 8th cranial nerve causing loss of coordination. Decreases cardiac output. Can be toxic to kidneys so encourage drinking with sugar water. Dose: 1-2 mg/lb SQ BID for 7-14 days. Brands: Gentocin, Garison.
Bacteriostatic Antibiotics
azithromycin—Same family as erythromycin but stronger and uses are the
same. Dose: 14 mg/lb BID for 2 weeks, then SID for 2 weeks. Brand:
Zithromax. Best given on an empty
stomach 2 hours after eating.
chloramphenicol—Broad spectrum, penetrates tissues that some other antibiotics can’t, like the central nervous system and eye, but not good for urinary infections. Effective against Mycoplasma. Long term use can depress bone marrow. Decreases cardiac output. Inhibits some hepatic microsomal enzymes and so prolongs effects of barbiturates. Oral liquid can sometimes be specially mixed at pharmacies. Use tablets with caution because if the powder is inhaled it can cause aplastic anemia in humans. Do not use with tylosin. Brand: Chloramycetin. Dose: 9-23 mg/lb 2-4 times/day orally or SQ. Tastes horrible so often better to give by injection.
doxycycline—Broad spectrum, related to tetracycline, but stronger, and precautions are the same except it does not bind to minerals. Effective against Mycoplasma. Can be used long term. Brand: Vibramycin. Dose: 2.5-5 mg/lb BID. Taste not too bad.
erythromycin—Supposed to be effective against Mycoplasma, Strep, Staph, Corynebacteria. Good for abscesses and prostate and respiratory infections. Dose: 10 mg/lb TID. Brand: Ornacyn (pet shops) 1/2-1 tablet per lb. in 1/4 cup drinking water mixed fresh daily, or 1/4-1/3 tablet per lb. in food TID. Tastes okay. Don’t give in fruit juice as may decrease effectiveness.
tetracyclines—Broad spectrum, effective against Mycoplasma, Pasteurella abscesses. Good for respiratory infections, prevention of infection after injury or surgery. Tolerated better than many other antibiotics. Don’t use in pregnant animals. Dose: 25 mg/lb BID. Brands: Panmycin Aquadrops; Ornacycline (pet shop)—1/2 tablet per lb in 1/4 cup drinking water mixed fresh daily, or 1/8 tablet per lb. in food TID. Terramycin Soluble Powder (feed store)--1/2 teaspoon per lb. in 1/4 cup drinking water, or 1/8 teaspoon in food TID. Taste not too bad. Aureomycin Soluble Powder (chlortetracycline--feed store). Dose: half that for Terramycin. May be more effective than tetracycline or oxytetracycline, but tastes worse.
trimethoprim sulfamethoxazole—Broad spectrum. Good for general, urinary, prostate, and secondary respiratory infections. Penetrates all tissues well. Can cause allergic reactions and renal obstruction. Patient must drink plenty of water. Long term use can decrease tear production and cause vitamin K deficiency. Various brands. Dose: 15 mg/lb BID. Tastes bad. Some rats will not take the liquid; use tablets ground up in food instead.
tylosin—Effective only against Mycoplasma, so not good for secondary bacterial respiratory infections. Do not use with chloremphenical. Brand: Tylan Soluble--1/8-1/4 teaspoon in 1 cup drinking water mixed fresh every 3 days, or 1/64 teaspoon in food BID. (To get 1/64 teaspoon, dump 1/8 teaspoon on a small plate and divide into 8 equal piles. Each pile is a dose.) Tylan injectable--Dose: 4.5 mg/lb BID. Can be mixed in liquid or food and given orally. Tastes horrible.
A Note About Doses
I have not included liquid doses for all medications because the dose will vary
with the concentration of the liquid. Here is how you convert a dose in mg to a
dose in ml. Find the concentration of the medication, which will be in mg/ml.
Divide this number by the dose in mg. Divide the results into 1. For example,
if the concentration is 50 mg/ml, and the dose you want is 10 mg, you need to
divide 50 by 10. This gives you the number of doses in one ml, in this case, 5.
Dividing 5 into 1 gives you the dose in ml, in this case 0.2 ml. (One ml is
exactly the same as one cc.)
To determine how many doses in a tablet or capsule, divide the strength of the pill by the required dose. For example, if the pill contains 50 mg and the dose is 2 mg, you divide 50 by 2, and you find that the pill contains 25 doses. If you need help figuring out doses, just give me a call.
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