Dosage Calculator


Loving rats since 2002.
Staff member
Jul 21, 2007
Northeastern Ontario
Here's a dosage calculator, it's very easy to use. You will need to know your rat's weight, drug dosage from low to high which is very convenient and concentration.

So for example, I used enrofloxacin, Baytril. I put the rat's weight at 500 grams. Or 0.500 kg. Dosages 10 mg/kg to 15 mg/kg for low and high and concentration at 25 mg/ml. This gave me a low dose of 0.2 to 0.3 cc. Very very useful tool!
Thank you piddlePod


Staff member
Supporting Member
Jul 21, 2007
Toronto, Canada, Earth
Here are some basic recommended dosages for some antibiotics and medications. This is not to be confused with the actual dose you give your rat.
There are 3 things you need when calculating a dose (weight of rat, concentration of antibiotics/medication and the recommended dosage (see below).

Baytril/enrofloxacin/ciprofloxacin - 15 mg/kg twice a day or BID (in a pinch you can double this dose and give once a day)
Doxycycline - 10 mg/kg twice a day or BID (in a pinch you can double this dose and give once a day)
Azithromycin/Zithro - 20 mg/kg once a day (SID)
Amoxicillin - 30 mg/kg twice a day (cannot be given once). In babies that aren't too sick you can give at 20 mg/kg. You might need to give a probiotic 2 hours outside of the antibiotic as it kills the good bacteria (gut flora) as well as bad, often causing loose poops. Not effective on myco.
Clavamox - 20 mg/kg twice a day (cannot be given once). This is like a supercharged Amoxi and you will have to use it the same way with probiotics.
TMZ, Trimethoprim Sulfa, TMS, Bactrim, Septra (the drug of a 1000 names) - 15 mg/kg twice a day. Very good drug for structural infections but doesn''t work on myco. Shouldn't be a first choice for respiratory infections.

Pain Medications
Metacam/meloxicam - good for pain and inflammation, never to be used with steroids. There's a range for use depending on what you are treating.
general inflammation (lungs/respiratory) 0.5 mg/kg once a day
significant swelling - 1 mg/kg (use until swelling comes down and either decrease dose or stop)
Post-op - 1 mg/kg
Insane emergencies ONLY - 2 mg/kg
Uusual range used is 0.5 - 2 mg/kg once a day. Some vets underdose Metacam so its best to double check the dose you are getting.

Ibuprofen - similar action as Metacam but must be given every 4-6 hours initially to work. 20 mg/kg every 4-8 hours is an effective dose. Advil pediatric drops are the best ones if you can get them. Children's is half the concentration so your doses will be bigger than infant. Do not use long term if possible.

Prednisone (oral) - 0.5 mg/kg to 2 mg/kg once a day. I use 1 mg/kg for most things. Cannot be given along with NSAIDs (Metacam/meloxicam, Ibuprofen). If you end up using it for more than a week you will need to taper down slowly and not stop cold which could be dangerous.
Dexamethasone/dex - 0.5 mg/kg to 2 mg/kg once a day. It comes in injectable form usually but can be given orally if necessary. Dex is fastest acting and longest lasting steroid for rats. I use 1 mg/kg for most things.

If anyone thinks of anything else they want help me just post below and I'll add it to the List :)


New Member
May 5, 2020
St Helens, Merseyside
Hi, not sure if this is the right place to ask this but I'm new to rat ownership and just had to take my three girls to the vets for URIs. I've been told to give each of them 0.03ml daily of Karidox for 7 days. They've given me a 1ml syringe and I was advised to mix it in with yogurt. This might sound a silly question but am I right in thinking the dosage is just the tip of the syringe, literally a couple of drops. I'm more use to guineas and I know they're a lot smaller but it doesn't seem enough. I know its difficult to say but does this sound about right?