by Debbie “The Rat Lady” Ducommun
Updated 11/29/17
This information 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, which can enter the body’s cells in order to hide from antibiotics. While antibiotic treatment can help control the disease, there is no known cure for rats.
Mycoplasmosis is extremely contagious and
baby rats contract the bacteria from their mother during birth. The disease has become so common that pretty
much all pet rats are infected, whether they have symptoms or not. Laboratory rats are free of the disease
because in the past, baby rats were delivered by Caesarian section while the
mother was submerged in disinfectant, sacrificing the mother. All laboratory rats in the world are now
descended from these hand-fed babies.
The Mycoplasma bacteria live in the lungs, therefore it is incorrect
to refer to “upper respiratory infections (
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. To see autopsy pictures of rat hearts, click here.
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.
(None of the organisms causing respiratory
infections in rats are infectious to humans. The only diseases I know of that can be
transmitted from domestic rats to humans are salmonella and “rat-bite fever,” a rare
bacterial infection similar to cat-scratch fever. For more info see my article at www.ratfanclub.org/fever.html.)
Common Symptoms
The first symptom of a respiratory infection is usually frequent sneezing
(healthy rats rarely sneeze) which can progress to wheezing. To hear examples of rats wheezing, click
here. Often,
the first symptoms of respiratory disease seen in a rat, especially in young
rats, will be caused by a secondary infection. Mycoplasmosis tends to be a slowly
progressive chronic disease that usually doesn’t cause symptoms until the
rat is older than 8 months of age.
For any symptoms, I recommend first trying amoxicillin, which tends to work
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 for myco is not as critical as it is for a secondary infection. I recommend that all rats owners have
amoxicillin on hand so sick rats can be treated ASAP.
******************************************************************************************************
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 PO, SC, IM q12h
(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
02/05/2006 “Amoxicillin is
safe to give rats.”
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
06/01/2007 “I have used
Clavamox a few times in rats without problems, although I am always very
careful to warn owners to watch for diarrhea.”
******************************************************************************************************
When treating respiratory symptoms in rats with amoxicillin, if the symptoms do not improve within 3 days of treatment, then you should switch to doxycycline, which tends to work well for mycoplasma.
Symptoms of advanced lung or heart disease
can include labored breathing, weight loss, blue extremities, and respiratory
distress, which can cause a rat to gasp through her mouth or become agitated
and dash about in panic. For the
treatment of respiratory distress, see the article on First Aid. If treatment cannot prevent such
attacks, euthanasia is the kindest action.
Mycoplasma usually causes only respiratory
symptoms. Other symptoms such as loss
of appetite, lethargy, rough coat, and hunched posture are usually caused
by a secondary infection or other disease, and should be treated immediately
with amoxicillin. A rat who is
extremely lethargic and refuses to eat or drink needs amoxicillin
force-fed.
An infection can also damage the nasal cavity resulting in bleeding, which
can be fatal. Nasal infections are difficult to cure and should be treated
long-term with amoxicillin.
(For how to mix and use amoxicillin see “Giving Medications” and “Mixing Medications in a Liquid” below.)
Rats with mycoplasma (all pet rats) will frequently exhibit
a behavior that is often mistaken for hiccups. The rat experiences rhythmic
jerks of his body for between several seconds to several minutes, usually about
2 jerks per second. Sometimes a sound can be heard at each jerk, but often there
is no audible sound. This is not hiccups. It is a sneezing jag caused by the
mycoplasma respiratory infection. In both coughing and hiccups air is expelled
from the mouth. When rats exhibit this behavior, you can see that their mouths
remain closed and air is only expelled through the nose, therefore it is
sneezing, not coughing or hiccups. I know it is caused by mycoplasma because
lab rats, who are myco-free, never do it. If your rats only do it
occasionally, you don’t have to worry about it. But if they do it a
lot, or if they start doing it more often, then you want to treat it with
antibiotics that work for myco. I recommend starting with doxycycline.
Secondary
Infections
Mycoplasma makes rats more susceptible to
secondary bacterial infections from a variety of bacteria. These infections are usually
opportunistic, taking advantage of a break in the immune system, and are not
usually contagious, but they can be deadly, and sometimes within just 12-24
hours! For this reason, I recommend
that amoxicillin be the first antibiotic tried in most cases. If your rat appears at all sick or
lethargic, I recommend starting him or her on amoxicillin ASAP! That is why I recommend all rat owners
have amoxicillin on hand at all times.
If a rat appears quite ill, then it
is a good idea to give both amoxicillin and enrofloxacin at the same time. Both are bacteriocidal and work well
together. Amoxicillin can also be
used in combination with doxycycline, because they work on different
bacteria. Another good combination
for severe symptoms is gentamicin and amoxicillin. (Gentamicin must be given by
injection as it is not absorbed by the digestive tract.) Both of these combinations target
secondary infections as well as mycoplasma. I recommend treating secondary infections
for a minimum of 2-3 weeks or until symptoms have been gone at least a week.
There is controversy whether rats can get
strep from a human with strep throat.
The organisms are supposed to be different (Streptococcus pyogenes
for strep throat, Streptococcus pneumoniae for rats) but there have been
some suspicious cases. It is
probably best for someone with strep throat to avoid rats.
Some books say that rats can get
“colds,” but they mean respiratory infections. Rats cannot get the human cold or flu.
Viral
Infections
There are two viruses that can cause
respiratory symptoms in rats.
Sendai virus causes a true respiratory infection. Sialodacryoadenitis (SDA) virus is an infection
of the salivary glands, but symptoms can include sneezing, wheezing, runny eyes
and nose, labored breathing, swelling of the glands under the throat, bulging
eyes and sudden death.
In mycoplasma-free lab rats these viruses
are not usually fatal to post-weaning rats and the rats recover in a week or
two. (Sendai can cause a stuffy
nose in infants which can prevent nursing and cause death.) However, for rats infected with
mycoplasma, a viral infection can result in fatal secondary infections. In fact, the first indication that a rat
colony has been infected with a virus can be the sudden death of one or two
rats. The disease is usually more
severe in older rats.
You can’t treat the virus, but you
can treat the secondary infections that cause the most danger. Sometimes treatment with amoxicillin or
amoxicillin and enrofloxacin (Baytril) is enough, and sometimes gentamicin with
either amoxicillin or cefadroxil is necessary. Aggressive supportive therapy, including
an injection of dexamethasone for inflammation, and fluids, might be
necessary. Treatment with ophthalmic ointment may be necessary to prevent eye
damage.
Both viruses will die out in a population
within 60 days if there are no new rats or babies. Charles Rivers Laboratories says the SDA
virus is only shed for 7 days, but an infected rat will usually have antibodies
to the virus for the rest of her life.
Disease
Transmission & Quarantine
Most pet rats get mycoplasma directly from
their mother during birth and so have it all their lives. Infected rats can transmit the disease
to mycoplasma-free rats (lab rats) through direct contact or repeated exposure
through the air. Because lab rats
don’t get mycoplasma at birth, if they are exposed later they seem to be
more resistant to it.
The rat viruses and some secondary bacteria
can be spread both through direct contact and through the air. Apparently, the SDA virus can live for 3
hours on inanimate objects, and longer in the human nasal tract, so after being
around strange rats it is best to blow your nose and wait 3 hours before going
home or visiting other rats.
When bringing a new rat into your colony, a quarantine is only necessary if the rat has been exposed to new rats in the previous 2 weeks. If the new rat
has been in the same living situation for the last 2 weeks, a quarantine shouldn’t be necessary. If the new rat has been exposed to other new rats in the
previous 2 weeks, or when bringing rats home from a show, it is best for them to be quarantined for at least 1-2 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.
Other
Causes of Respiratory Symptoms
Some rats are sensitive to some
beddings—most commonly CareFRESH—and can sneeze when exposed to
them. Pine and cedar shavings, which are toxic, can cause sneezing. I recommend using rabbit food as bedding
in rat cages. It is cheap in big bags from a feed store and very good at
controlling odor.
Allergies are rare, but can occur. I know of a rat who wheezed in response
to yogurt drops, and 2 brothers who sneezed when exposed to dogs! The most common foods to cause allergies
in rats are peanuts and dairy products, including yogurt drops.
Congestive heart failure, which is also
very common in rats, can also cause respiratory symptoms. Lung tumors are very
rare. Since 1985 I have done gross
autopsies on more than 250 rats and I have seen only 2 lung tumors,
although I have seen 4 chest
lymphomas.
Most respiratory symptoms in rats are caused by respiratory infections or heart disease, but tumors in the chest can also cause labored breathing. 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, but lymphomas of the chest are more common—I have seen 7 of them.
Inner
Ear Infections
Inner ear infections are common in rats.
They may be caused by mycoplasma or a secondary bacteria such as Streptococcus
moniliformis or Pseudomonas. The infection causes inflammation in
the inner ear, affecting the rat’s balance. This will cause the rat to
hold his head tilted to one side. This is why some books call this disease
“wry neck” but it has nothing to do with the neck. Without
treatment, the loss of balance can get so bad the rat will roll over and over
and is unable to eat, therefore, immediate aggressive treatment is necessary. A
rare possible side effect is facial paralysis (see my Rat Health Care booklet.)
I recommend treating with
either enrofloxacin and amoxicillin together, or chloremphenicol. An
anti-inflammatory must also be given to reduce the swelling in the ear.
Dexamethasone or prednisone is best. If necessary you can also try ibuprofen.
If the treatment is going to work, you should see significant improvement
within 2-3 days. If not, switch antibiotics. Continue treatment until symptoms
are gone for a week or until it has been a week since you have seen any further
improvement. At this point it isn't likely to improve any more. An inner ear
infection can result in a permanent head tilt, even if treated, but a mild head
tilt won’t affect the rat much.
Treating
Mycoplasma
The antibiotics that tend to be most
effective against mycoplasma are doxycycline and enrofloxacin. There are different strains of
mycoplasma that are more or less resistant to various antibiotics. In some cases, a strain will respond
best to both doxycycline and enrofloxacin together.
Because mycoplasma is a very resistant
organism, treatment must be persistent.
Humans can contract a version of mycoplasma which is a different disease
than what rats get (humans get Mycoplasma pneumoniae) and when they do
the treatment is antibiotics for 1-2 years!
I recommend treating mycoplasma for at
least 6-12 weeks at a time or even much longer. An older rat with chronic symptoms
and/or heart disease should be on enrofloxacin and/or doxycycline for
the rest of his life. Both these antibiotics are usually
well tolerated by rats for long periods of time. I have had some of my rats on
enrofloxacin or doxycycline for over a year with good results, and one of my
vet’s patients lived to be over 4 years old and was on Baytril the last 2
years of her life!
Other
Respiratory Medications
If your rat’s nose seems congested,
the decongestant pseudephedrine might help (use carefully in rats with
congestive heart failure). Buy the
non-drowsy pediatric formula. A product also containing guivesan seems to dry
them out less. The dose is 1.5
mg/lb, 3 times a day. An antihistamine can be helpful in some cases, and
especially, of course, if the symptoms are caused by an allergy. For doses, see
my Rat Health Care booklet.
Remember that these medications only treat the symptoms, not the cause.
A bronchodialator
can be very helpful in rats with labored breathing or respiratory
distress. The one I use the most is
aminophylline, but I have also used theophylline for a rat who hated the taste
of aminophylline. Aminophylline can
be given either orally for long-term treatment or by injection in an emergency.
The dose for aminophylline is 2.5-5 mg/lb 2 to 6 times a day. You can also try
Primatene tablets which are available over-the-counter. Try a dose of 1 mg/lb 2 to 6 times a day.
An anti-inflammatory can also
be very helpful to reduce inflammation in the lungs. Ibuprofen has been helpful in several
cases, and I use prednisone extensively.
The dose for ibuprofen is 60 mg/lb. For more info on giving it, see the
First Aid section on the Rat Info page. The dose for prednisone is 1 mg/lb
twice a day. For severe acute infections, an injection of dexaphosphate or
dexamethasone, at a dose of 1 mg/lb, are stronger. You should see improvement within 12
hours.
If there is excess fluid in the lungs, a diuretic can be helpful. I’ve had good results with Lasix (furosemide) at a dose of 1-2 mg/lb 1-3 times/day. You should see improvement with oral dosing within 12 hours, and with an injection in a few hours. Vitamin B6 can also act as a diuretic. I suggest trying 5-10 mg per 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.
Treating
Congestive Heart Failure
I have found that rats with advanced respiratory disease often have congestive heart failure as well. The recommended treatment for heart failure is a low sodium diet, enalapril (1-12 mg/lb twice a day), which lowers the blood pressure and makes it easier for the heart to beat, and atenolol (1-4 mg/lb twice a day), an beta-blocker that slows the heartbeat to make it more effective. (The American Heart Association recommends 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 improves your rat’s symptoms, then you know he has congestive heart failure. If enalapril is going to help you should see improvement in the rat’s symptoms within 1-5 days. A diuretic can also help in some cases. For more information about congestive heart failure, see my Rat Health Care booklet.
Other
Treatments
Moisturizing the air with a humidifier can
help some rats breathe more easily.
A product called VetRx or FerretRx can help
in some cases. It is aromatherapy
that 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 where it will be inhaled 2-3 times a day. Do not rub it on your rat’s nose
as 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.
Look for these products in pet shops and feed stores. Another essential
oil that can help is eucalyptus, or you can use Vicks Vaporub.
If a rat is having gasping attacks, he will
swallow large quantities of air which he can’t burp up. This will cause stomach distension and
discomfort. In severe cases it can
press on the chest and make the breathing worse, so the air must be removed
from the stomach through needle aspiration.
If the rat is no longer gasping (a rat in
respiratory distress will not be able to take oral medications) but still has a
distended stomach, you can try using the product Gas-X. Try giving about ¼ teaspoon.
When a rat is experiencing severe labored
breathing or respiratory distress, oxygen therapy can be beneficial. It can make the rat more comfortable
while you wait for medications to work.
Gas oxygen must be prescribed by your vet. You can rent or buy bottled oxygen, and
you can also buy a machine that concentrates oxygen out of the air. Used oxygen concentrators are sold on
eBay without a prescription for around $200-300. You can use a 10-gallon aquarium as an
oxygen chamber, or make a chamber as for nebulizer treatments (see below). The rat will need to live in the chamber
until other treatments insure comfort outside the chamber. Don’t forget a water bottle.
If respiratory symptoms do not improve in
an oxygen chamber, it means the lungs are not capable of oxygen exchange, and
the rat should be immediately euthanized.
Aggressive
Treatment
You can significantly improve the health
and life span of most rats with respiratory disease by treating all symptoms
promptly, continuing antibiotics for the treatment periods I’ve
recommended, and trying new medications if one is not working. Treatment for
heart disease is also important.
Even if your rat becomes very sick,
don’t give up. I’ve seen several rats pulled back from the brink of
death after receiving the correct medications, recovering their health to live
for several more months. Although
respiratory and heart disease are extremely common and can be devastating,
prompt and persistent treatment with medications that work for your rat can
help keep the diseases in check in most cases, and will usually allow your rat
to enjoy a long happy life.
Giving Medications
The easiest way to give medications is to mix them into a yummy liquid. To do this you need syringes for accurate measurement. For capsules, just pull them open and dump out the contents into the flavoring. Most tablets will dissolve in a liquid overnight, but they can also be ground up for immediate mixing. Some ideas for the flavoring are: Ensure, powdered soy infant formula mixed up fairly thin, soy milk or almond milk plain, or flavored with fruit syrup, slightly diluted strawberry sundae syrup or pancake syrup (try blueberry), or molasses diluted 1:1 with water. Flavored syrups may also be available from your vet or pharmacist.
If you don’t have syringes for measuring, you can grind tablets or the contents of a capsule into a fine powder on a small plate with a spoon and divide the powder into the proper number of doses. You can then mix each dose in food. Some suggestions for foods to put medications into include baby food, pudding, mashed avocado, yogurt, brown sugar and carob powder, honey, peanut butter 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. 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 a rat dislikes the taste—or the aftertaste—of a liquid, it is still possible to administer it if you give only 0.1 ml at a time. You can force this tiny drop into the back of a rat’s mouth and it’s too small to be spit out.
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. 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.
Antibiotic Treatment
Antibiotics are different from other drugs in that they don’t work
directly on the patient; instead they work on bacteria inside the
patient’s body. In general,
it is better to give a higher dose rather than too little as the levels in the
blood must be high enough to do their job.
Antibiotics must be selected carefully not only according to what type
of bacteria may be 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.
Antibiotics are divided into two groups according to how they
work. Bactericidal antibiotics
actually kill the bacteria but only when they are growing. Bacteriostatic antibiotics prevent the
bacteria from growing, so the immune system can kill them off. Bacteriocidal types should be used for
serious acute infections whenever possible.
Some antibiotics have a synergistic effect, having a greater effect
together than when used alone. This
occurs when gentamicin is used with the penicillins, which assist gentamicin in
penetrating the bacteria’s cell wall.
Bacterial
Resistance
There is some confusion about resistance to antibiotics. It’s not the patient that develops
a resistance to an antibiotic, it is the bacteria. A particular type of bacteria might develop
a way to withstand the action of an antibiotic. This is more likely to happen when the
antibiotic is only given for a short period of time, if it is given off and on,
or if it is given at a less than optimum dose. The bacteria might be able to withstand
a short weak attack but not a longer stronger attack. This is why when treating respiratory
infections in rats it’s not a good idea to give an antibiotic for
mycoplasma for less than 6 weeks,
or to use antibiotics in a on-off, on-off fashion. It’s better to use the antibiotic
steadily for a long time. If
bacteria become resistant to an antibiotic, then a different antibiotic must be
used. Using two antibiotics
together can sometimes also overcome resistance.
Using
Antibiotics
If a particular antibiotic is effective against an infectious organism,
you should see an improvement in acute symptoms within 2-3 days, or in
chronic symptoms in 3-5 days.
Don’t keep using the same treatment if there is no
improvement in the symptoms! With any treatment you should continue to
see steady improvement in the symptoms.
If you don’t, try another antibiotic. (See Flowcharts on page 26-28 of my Rat Health Care booklet.) If the symptoms come back, restart
the treatment and continue it at least twice as long.
When a rat is severely ill, it is a good idea for the first dose given
to be extra strong, sometimes twice the normal dose, to get the patient off to
a good start. In general, the length of treatment for infections affecting the
skin should be at least 10-14 days.
Respiratory and urinary infections generally need to be treated for several
weeks.
I recommend continuing treatment for secondary respiratory
infections for at least 2-3 weeks, or until the symptoms have been gone for
at least two weeks. In cases of
chronic respiratory infections, treatment can and should be continued for
longer than this. However, some
antibiotics, such as gentamicin and chloremphenicol should not be used longer
than 14 days. For mycoplasma
the course of treatment should be at least 6-12 weeks and sometimes
for the rest of the rat’s life.
Most Useful
Antibiotics
I have found the most useful antibiotics for rats to be amoxicillin,
doxycycline and enrofloxacin (Baytril).
For the past 10 years or so I have hardly used anything else. I find that respiratory symptoms that
don’t respond to these antibiotics are usually caused by congestive heart
failure.
amoxicillin
Amoxicillin is a broad spectrum antibiotic in the penicillin family. It
is bacteriocidal. Although it is not effective against Mycoplasma, it is
the best choice for all other bacterial infections in rats, especially
abscesses, and the first antibiotic I always recommend trying.
Even if a rat is on doxycycline or enrofloxacin for mycoplasma, if he develops
symptoms of a secondary infection (see page 24), he should be put on
amoxicillin in addition to the other antibiotic. Amoxicillin also helps
Baytril work more effectively for urinary infections in rats.
Amoxicillin is one of the only antibiotics that is perfectly safe to
give to pregnant and nursing mothers and babies of any age. (Another is
cefadroxil, and cephalexin can be given to nursing mothers as it does not enter
the milk.)
Amoxicillin has a wide dose range of 22-110 mg/kg (10-50 mg/lb)
Amoxicillin only tends to cause diarrhea in a few individual rats. Mild
diarrhea can be treated with probiotics, but if it is severe, stop the
amoxicillin as soon as possible.
The most common brand prescribed by veterinarians is Amoxi-drops, a
bubblegum-flavored liquid of which the normal dose is 0.44 ml/kg (0.2 ml/lb). But
amoxicillin capsules can also be used and mixed into a liquid at home, and are
a lot cheaper. Amoxicillin tastes okay to most rats and so is usually no
problem to give in any form. An occasional rat will hate the taste.
Amoxicillin usually comes in a 250 mg capsule, which contains 25 1-lb.
doses. To mix it, I suggest putting one 250 mg amoxicillin capsule in 7.5 ml of
flavoring. Then the dose is
0.3 ml/lb, the dose for a half-pound rat is 0.15 ml and the dose for a
1¼-lb rat is 0.4 ml. For a tiny baby, give one drop. For a 500 mg
capsule, use double the amount of flavoring. Amoxicillin capsules are good for
years after their expiration date, and all amoxi, whether for fish, dogs or
humans, is the same.
For rats who won’t take amoxicillin willingly, you can make the
dose 0.1 ml/lb so it can be easily forced, by mixing one 250 mg capsule with
only 2.5 ml of flavoring.
Note that amoxicillin powder does not dissolve in the flavoring and
will sink to the bottom. Before taking out a dose, you must stir the mixture
well with the syringe, which works better than shaking it, to get the powder in
suspension. When refrigerated, the mixture will be good for 2 weeks.
Amoxicillin is available over the counter for fish. You can order it from www.fishmoxfishflex.com and also
Jedd’s Pigeon Supply and Drs. Foster and Smith (see sources below.)
Other antibiotics in the Penicillin family:
ampicillin—Can be used instead of amoxicillin,
but is not as well absorbed, so you must give double the dose. Do not use with atenolol. 20 mg/lb
amoxicillin
trihydrate/clavulanate^—Effective
for some bacteria that are resistant to amoxicillin. Good for skin infections and abscesses.
Some individuals are sensitive to the clavulanate ingredient. 10 mg/lb
NOTE: Some vets won’t prescribe amoxicillin for rats because they learn in vet school that amoxicillin can kill hamsters or guinea pigs, so they sometimes generalize this to all rodents. Here are some references for vets 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 PO, SC, IM q12h (Note: ampicillin and amoxicillin are essentially the same)
ViN (Veterinary Information Network, Inc.) Website: Thomas Donnelly, BVSc on 02/05/2006 “Amoxicillin is safe to give rats.”
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
Blackwell’s Five-Minute
Veterinary Consult: Small Mammals, Second Edition, Barbara L. Oblesbee. 2011 John Wiley & Sons, Inc.
page 588, “amoxicillin/clavulanic acid (12.5-15 mg/kg PO q12h) may also
be used.”
doxycycline
Doxycycline is related to tetracycline but is absorbed better and does
not bind to minerals as much. Doxy
tends to work well against Mycoplasma in rats, but in rats is not good
for much else. It is bacteriostatic.
This is the second antibiotic I recommend trying for respiratory
symptoms in rats after amoxicillin.
It often works well together with enrofloxacin. It should not be used in pregnant or
nursing moms. It can increase the
side effects of digoxin, so enrofloxacin is better for rats on digoxin.
Doxycycline is one of the few medications that can become dangerous
after its expiration date. It can change chemically and become toxic to the kidneys,
so must be thrown out after its expiration date.
The most common brand prescribed by vets is Vibramycin, a flavored
liquid, but you can also buy it yourself.
Doxycycline is available over the counter for fish and birds.
Doxycycline comes in either a liquid, or 100 mg capsules or packets,
which can be mixed into a liquid.
100 mg contains 40 1-lb doses.
I normally recommend making the dose 0.3 ml/lb, so to do this, you mix
one capsule with 12 ml of flavoring. (40 X 0.3 = 12 ml) I recommend mixing it with either
slightly diluted strawberry syrup, or almond milk flavoured with strawberry
syrup. Store it in the
refrigerator. It will be good for at least 2 weeks.
The
best option for doxycycline now is probably to order Doxysyrup or Doxyvet
Liquid from Jedd’s Pigeon Supply. Most people will want to order
Doxysyrup, which is 10 mg/ml. The normal dose is 0.25 ml/lb twice a day. If
necessary you can give twice this.
If
you own a lot of rats, the most economical choice is Doxyvet Liquid, which is
50 mg/ml. The normal dose is 0.05 ml/lb twice a day. If necessary you can give
twice this. I have heard from several rat owners that this liquid is not as
palatable as the Doxysyrup, but it can be diluted with yummier liquid or mixed
with food. If you mix 1 ml of the Doxyvet with 5 ml of flavoring, and then the
dose is 0.3 ml/lb twice a day. Depending on the flavoring you use, the mixture
should probably be refrigerated.
You might also want to search
on eBay or Amazon to look for other sources of doxycycline. Be sure to get
either capsules or powder packets, not loose powder, and look carefully at how
much you will get for the cost, because some vendors charge a lot of money.
Most rats don’t mind the taste of doxy, but some absolutely hate
it and will fight against taking it.
In this case, it is usually best to use enrofloxacin (Baytril) instead.
At
Jedd’s most people will want to order Doxysyrup, which is 10 mg/ml. The
normal dose is 0.25 ml/lb twice a day. If necessary you can give twice this. If
you own a lot of rats, the most economical choice is Doxyvet Liquid, which is
50 mg/ml. The normal dose is 0.05 ml/lb twice a day. If necessary you can give
twice this. Some rats don’t like the flavor but it can be diluted with
tastier liquid.
The usual dose of doxycycline is 2.5 mg/lb
If you have a rat who refuses to take the doxy voluntarily, and you
need to force it, you can make the dose only 0.1 ml/lb. If you put only 0.1 ml
of liquid in the back of a rat’s mouth, it is too small for them to spit
out. In this case you can mix the capsule with only 4 ml of flavouring, making
the 1-lb dose only 0.1 ml. However,
in this case, it is better to switch to Baytril. Usually, a rat who hates doxy
will take Baytril okay, and vice versa.
Baytril (generic name:
enrofloxacin)
Enrofloxacin is a broad spectrum antibiotic in the fluoroquinolone
family. It is bacteriocidal. It is particularly good for Mycoplasma. It can also be good for urinary
infections when used along with amoxicillin. It can safely be used very long term in
rats (ie. 2 years!) Other brand names are usually similar to enrofloxacin, ie.
Enrofloxin.
Enrofloxacin can be combined with doxycycline, penicillins,
cephalosporins or gentamicin. Do
not use it with chloremphenicol. It
can interfere with the metabolism of bronchdilators, so doxycycline is
better to use for rats on a bronchodilator.
The brand usually prescribed by vets is Baytril. The injectable form is
usually 2.25% (22.5 mg/ml). Vets will sometimes want to give Baytril by
injection, but it is highly caustic: DO NOT give Baytril by IM injection
and only SQ when absolutely necessary as SQ injections can cause
severe skin ulcers which take a very long time to heal. I know of two rats who bled to death
after scratching these ulcers!
Some vets grind Baytril tablets and mix them in a liquid
flavoring. These preparations
should probably be refrigerated. The injectable liquid, which can be given
orally, or 10% oral liquid should NOT be refrigerated because it will
crystalize.
The recommended dose of enrofloxacin for rats is 10 mg/lb
Clear liquid Baytril, either injectable or oral, tastes pretty bad and needs to be mixed with more flavouring than most other medicines. I don’t recommend
mixing up a lot of it ahead of time as that may affect its potency. I’ve had the best luck giving Baytril 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.
If you want to mix some of the Baytril up ahead of time, you can mix
0.5 ml of the 10% liquid enrofloxacin with 4.5 ml of flavouring. The 1-lb dose
is then 1 ml.
Other
Antibiotics
Although
amoxicillin, doxycycline, and enrofloxacin will take care of most infections in
rats, occasionally another antibiotic will be necessary. I highly recommend my Rat Health Care booklet as a reference.
Sources for
Antibiotics
Some antibiotics
can be purchased over the counter for different animals: amoxicillin and
ampicillin for aquarium fish;
doxycycline and enrofloxacin for birds. Prescription drugs can be
purchased either from your vet, a human pharmacy (often cheaper), or a mail
order catalog.
When ordering an antibiotic by mail order, be sure to specify if you
want capsules, packets, or liquid, or you might get loose powder
or tablets instead.
Here are some sources:
Jedds
Pigeon Supplies , 800-659-5928 *My
preferred source
for
liquid doxy and 10% liquid enrofloxacin. Also amoxi capsules. Orders can be
made by phone. Doxysyrup is 10 mg/ml, so the normal dose is 0.25 ml/lb twice a
day. Doxyvet Liquid is 50 mg/ml, and more economical. The normal dose is 0.05
ml/lb twice a day. It can be diluted with tastier liquid.
www.fishmoxfishflex.com *My preferred source for amoxi capsules for fish
www.allbirdproducts.com 10% liquid enrofloxacin,
doxy
www.ladygouldianfinch.com
10% liquid enrofloxacin, doxy
Doctors Foster & Smith, 800-826-7206 amoxi capsules for fish
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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