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Pet Rats/2 year old Male Rat w/ redness on penile sheath


Basil 2/19/13
Basil 2/19/13  
QUESTION: I have a 2 year old male rat (Basil) who I'm a bit worried about.  Just yesterday I noticed that he has a bit of a red ring developing around his sheath. Or at least I think that's the correct body part. You can't see it just by looking at him. You have to start pushing his penis out just a bit. And even then, his actual penis isn't popping out yet, so the tip of the covering for his penis is the part that is red. I have a picture, sorry if it's a bit blurry; he didn't exactly cooperate!

Anyway, he has been a bit depressed and sleepy lately. We just lost his brother very unexpectedly almost 2 weeks ago. They each had their own cages for the past year due to constant fighting, but they were neighbors. One of the things we noticed during Jinxie's last hours was a gelatinous like pee. A few days after his passing, my boyfriend said he noticed the same kind of thing on Basil, but before he could get a better look at it, Basil groomed himself down there and ate it. I did a little research and learned that it could either be a UTI or a penis plug. I had never heard of penis plugs before, but read that as rats get older they can have trouble cleaning themselves as well as they used to, and it is important for us parents to check their privates. He didn't let me for a couple days, but I finally got a look at it the other day and noticed the redness. I thought maybe he had just been grooming it too much and I would give it another day. I just checked it now (day 2) and it is still red. According to some things I found on google, this could be Paraphimosis?  He still seems to be peeing, and his penis is not stuck out, but I do not want to let it get to that point.

Any suggestions?  Is there anything I can do to help him at home?  I don't mind taking him to the vet but it wouldn't be until the day after tomorrow, if it's ok to wait till then. He seems ok other than that, though. I just want to keep him happy and comfortable. Also, do you know of any good rat vets in the Silver Spring, MD area? The vets I've been to in the past will see rats, but I'm not convinced they are totally comfortable/know their rattie stuff, especially when it comes to non-generic small animal issues.

Thank you for any advice! I'm a big fan, and my boys love(d) your tofu/molasses recipe :)


It doesn't seem to me that the color around his penis is anything to worry about. It doesn't look irritated or inflamed in the picture. However, I'm concerned about his lethargy. I suggest putting him on amoxicillin in case he has a secondary bacterial infection. See more info below.

You'll find a list of vets on my website at on the Rat Info page to hopefully help you find a better rat vet. But, sometimes you need to use one that is at least willing to read and follow my advice.

For a rat who is sick, no matter the symptoms, amoxicillin is the first treatment I recommend.  Secondary infections, which can include respiratory symptoms, lethargy, poor appetite, and other symptoms, are common in rats, especially young rats and those from pet shops. Older rats can also get secondary infections on top of mycoplasma. In my experience, amoxicillin is the best treatment for secondary infections in rats.  Amoxicillin capsules are good to have on hand for secondary infections, which can get very severe very quickly, killing a rat in a matter of hours or days, and require immediate treatment.  Amoxicillin is also best for skin infections. (However, amoxicillin does not work against mycoplasma. For that I recommend doxycycline, and maybe also Baytril.)

All vets will have amoxicillin, and you can also get amoxicillin over the counter as aquarium fish capsules from some feed stores and specialty aquarium stores. Call the stores in your area and ask before driving there.  Do NOT tell them you are buying it for your rats!  It is legal for them sell it over the counter only for fish.  You will not find it at Petco, PetSmart, etc.  If you can’t find amoxicillin, you can use ampicillin which is basically the same thing, it just isn’t absorbed as well, so just double the dose to 20 mg/lb twice a day.

Some vets won’t prescribe amoxicillin for rats because they learn in vet school that you can't give amoxicillin to hamsters or guinea pigs (it will kill them) so they sometimes generalize this to all rodents.  But amoxicillin is fine for rats and mice, whose digestive systems are very different from quinea pigs and hamsters.  I use it all the time.  (For more about getting your vet to prescribe amoxicillin, see the info at the bottom.)

Rarely you will have an individual who will be allergic or sensitive to amoxicillin, and the most common side effect is diarrhea.  In most cases, this diarrhea is mild enough to be controlled with probiotics (good bacteria for the intestines) but if the diarrhea is severe it will stop when you discontinue the treatment with amoxicillin.

You can order amoxicillin capsules from If your rat is already sick, be sure to ask for overnight delivery!

You can also get amoxicillin mail order from Jedd’s Pigeon Supplies at 800-659-5928.  Ask for Greg, and be sure to order CAPSULES.  Also, you can get it from Doctors Fosters & Smith, 800-826-7206.  Order the capsules for aquarium fish, item #CD-18876.  (Please note that they sometimes change the item number, so just search for amoxicillin in the fish department.)  

You need to know about how much your rat weighs.  The dose is 10 mg/lb twice a day but you can safely go as high as 50 mg/lb.  In most cases (check the package) each amoxicillin capsule contains 250 mg, which is 25  1-lb doses.  

If you have access to small syringes for measuring you can mix the amoxicillin in a liquid.  Amoxicillin does not dissolve but forms a suspension.  The powder will sink to the bottom, so before taking out a dose, you need to stir the mixture with the syringe extremely well, being sure to scrape up all the powder off the bottom so it is in suspension.

Mix one capsule of 250 mg amoxicillin in 7.5 ml of liquid such as Ensure or slightly diluted Hershey’s strawberry syrup. (If you have 500 mg capsules, use twice the amount of flavoring: 15 ml.) A small pill bottle is about the right size to mix it in.  Keep in the refrigerator.  Amoxicillin doesn’t taste too bad to most rats and most rats will eagerly lick this right from the tip of the syringe.  The normal dose is 0.3 ml/lb twice a day.  (Note: 1 cc = 1 ml = 100 units on an insulin syringe, so 0.3 ml = 30 units.)  You can go as high as 5 times that normal dose if necessary, and it’s a good idea to give a double dose the first time.

If your rat won’t take the amoxicillin mixture voluntarily, you can make the dose 0.1 ml which is too small for them to spit out when you put it in the back of their mouth.  Mix one capsule with 2.5 ml of flavoring. Then the dose is only 0.1 ml/lb twice a day.

If you don’t have small syringes, you can mix it in food.  Dump a capsule out on a plate.  If it is granular, grind it to a powder.  Divide the powder in half, and half again, etc.  Until you have 24 piles. Since it’s hard to divide it more than this, you can give the 1-lb dose to rats who weigh less than a pound.   It’s better to give too much than not enough.  Scrape a pile into a little bit of food such as baby food, mashed avocado, etc.  

Give the dose twice a day.  If it's going to work the symptoms should improve within 2-3 days.  If it does work you need to continue the treatment for at least 2-3 weeks.  If it doesn’t work then you need to try a different treatment.  If the symptoms are all gone within 3 days you should continue the treatment for 3 weeks.  If it takes longer for all the symptoms to go away, give it for 4-8 weeks and maybe longer.  The longer it takes for all the symptoms to go away, the longer you should continue the treatment.  If the symptoms stop improving, or if the amoxicillin doesn't help at all, you will need to try something else.

You can buy 100 ml of 10% oral generic Baytril (enrofloxacin but they call it Enroxil) from Jedd's Pigeon Supply for $40 plus shipping.  The dose for a 1-lb rat is 0.1 ml, which means that 100 ml is 1000 rat doses!  Very economical.   You need to give it twice a day.  Do not refrigerate the Baytril!
I’ve had the best luck giving it in 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.  

Jedd’s Pigeon Supplies is 800-659-5928. If you order by phone ask for Greg. When ordering, just ask for the 10% Enroxil.  Do not say “for my rats” because it is available without a prescription for pigeons only.  Greg is cool about it though.  You can also order it on their website at If ordering online, order item #5002.  It won’t say it’s Baytril, as they keep it quiet.

You can also get doxycycline capsules from Jedd's.  Ask for Greg.  Be sure to ask for CAPSULES otherwise they will send loose powder.  It will cost about $35 for 100 capsules of 100 mg each plus shipping.  Don’t say “It is for my rats.”  You can only buy them over the counter for birds. However, Greg is very cool about it.

To mix doxycycline capsules:

In a small pill bottle, put 12 cc (12 ml) of liquid such as Hershey’s strawberry syrup.  Open and dump in the contents of one 100 mg doxycycline capsule.  Stir well.  The amount for the typical dose of 2.5 mg/lb is 0.3 ml/lb (0.3 cc or 30 units on an insulin syringe) twice a day.  For 5 mg/lb give twice that.  To use an insulin syringe for oral dosing, break off the whole needle assembly.  Be sure to refrigerate the mixture.

If you don’t have the proper syringes for dosing, dump the capsule out on small plate and divide the powder into 40 equal piles.  (Divide in half, then in half again, etc.)  Each pile is a dose and can be scraped into soft food.

You will find more info about treating respiratory infections on my website at on the Rat Info page.  I also highly recommend you order my Rat Health Care booklet.  It is only $7 plus $2 shipping (CA residents add 58 cents tax.)  The address is Rat Fan Club, 857 Lindo Lane, Chico CA 95973.

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 PO BID.”
(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.  I  generally have gone with a dose more similar to dogs and cats (20-30 mg/kg BID) but if you search on PubMed you will find all sorts of much higher doses.”

---------- FOLLOW-UP ----------

QUESTION: Thank you SO much for all the info!  This has been a huge help. I ordered the amoxicillin from the aquatic pharmacy, should be here today or tomorrow and then I will start Basil on it ASAP. I do have a question about the doxycycline, though.  He's always had a bit of redness around his eyes and nose, but it's gotten a bit worse lately. I do have Baytril and Doxycycline from my other boy.  I think i should start giving him somehing to help with the myco. My question is regarding the dosage of the doxycycline.  most of the things I've read are dosages for a 100mg pill I think. This bottle says that the suspension is made with 50mg pills. The dosage on the bottle says to give 0.06cc's every 12 hours.  But this was for treating an inner ear infection. So I  just want to double check with you how much you would reccomend to give Basil for his respiratory issues?  He is around 1 1/2 lbs.

Should I just start with the doxy and see how that goes? Or do I need to give him the doxy and the baytril together?  I was hoping to just be able to do the doxy and the amoxicillin, once it gets here.  Thanks again for all of your help!


ANSWER: Good!  Yes, it wouldn't hurt to put him on the doxy also. Does the bottle say what the concentration is?  That is, the mg/ml?  Without that, I can't really tell you how much to give. So, I'm assuming a vet mixed it up? If the concentration isn't on the bottle, you'll need to call them and ask what it is. 0.06 is a tiny tiny amount. It would have to be very concentrated for that to be the proper dose for a rat. At his weight, he should get 3.75 mg to 7.5 mg twice a day.

---------- FOLLOW-UP ----------

QUESTION: I just heard back from the vet, and they said the doxy is a 50mg/ml concentration.   How much/how long do you think I should give it to him?

The amoxicillin just got hear, too! They are the 250mg capsules. So I will start him on the .3 cc's tonight. Your previous response said that it can be a good idea to double the first dose, so should I give him .6 tonight, then .3 the other times? Again, just want to make sure so I give him the best chance to respond to the meds.  Thanks so much for all your help! Sorry if some of my questions are a bit repetitive, I'm just a worried mother!  :P


Okay, the doxy is 50 mg/ml. I guess that is really concentrated!  His dose would be 0.08 to 0.16 ml twice a day. The lower dose would be the normal dose, which can be doubled if necessary.

The 0.3 ml of amoxicillin is for a rat who only weighs 1 lb, so since he weighs 1 1/2 lb his dose is 0.45. So, yes, give him a double dose of the amoxi tonight, 0.9 ml.

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Debbie Ducommun


I can answer any questions about pet rats, but you will probably be able find answers to simple questions more quickly on my website at If you have a life-threatening emergency you can try calling me at 530-899-0605. I am not usually on the computer on the weekend.


I have been "The Rat Lady" since 1985 and am recognized as one of the world's experts on pet rats. I have 3 published books and already answer lots of questions about rats daily.

President of Rat Assistance & Teaching Society

I am a monthly columnist for Pet Business magazine, and my writing has appeared in other magazines. I have 3 published books.

BA in Animal Behavior

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