Pet Rats/septrin


Dear Debbie
Our rat Fang had respitory infection and was treated with baytril and metacam.  he made massive improvement but still constantly snuffles mainly at night time.  The vets have now given him 14 days of septrin 0.33 twice a day.  He seems to be snuffling and sneezing even more in the three days he has been on it.  I want to ask them to change him back to baytril but don't know if they will insist that I should see the 14 days through.
in your experience should I ask the vet to change him back to baytril ?


Hi Helen,
Since the septra is not working, you do not need to continue it for the 14 days. Yes, ask to go back to the Baytril. How long was he on it?  I recommend a minimum of 6 weeks for Baytril because the mycoplasma it treats is incurable and must be treated aggressively.

Since the Baytril didn't seem to totally take care of the problem, I would also recommend amoxicillin be used along with it. It is for secondary infection, like the Septra, but tends to work much better in rats than the Septra, which I don't think works much at all. See the info below, which is from my Rat Health Care booklet, which you can read about on my website at on the Books page.

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, and they usually tolerate amoxicillin quite well. I use it all the time. 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.”

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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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