Chapter 1
Amoxicillin-Clavulanate (Clavamox)
Feline Medication Reference
This page summarizes published veterinary infectious-disease guidance for amoxicillin-clavulanate in cats. Dosing recommendations may differ depending on the type of infection.
Always calculate the dose from the cat’s current weight and the concentration of the medication being used.
QUICK REFERENCE
Respiratory infections
ISCAID feline dose:
12.5 mg/kg by mouth every 12 hours
Equivalent to approximately:
5.7 mg/lb every 12 hours
The dose refers to the combined amount of amoxicillin + clavulanate.
Example
A 2 lb kitten weighs approximately 0.91 kg.
0.91 kg × 12.5 mg/kg = 11.4 mg per dose
A 4 lb cat weighs approximately 1.81 kg.
1.81 kg × 12.5 mg/kg = 22.7 mg per dose
A 6 lb cat weighs approximately 2.72 kg.
2.72 kg × 12.5 mg/kg = 34 mg per dose
These calculations determine the amount of medication in milligrams. The amount in milliliters depends on the concentration of the liquid.
WHEN IS AMOXICILLIN-CLAVULANATE APPROPRIATE?
ISCAID lists amoxicillin-clavulanate as an option for secondary bacterial respiratory infections involving susceptible organisms such as:
Pasteurella species
Streptococcus species
Methicillin-susceptible Staphylococcus species
Many anaerobic bacteria
Most Bordetella bronchiseptica isolates
It does not provide effective treatment for every cause of feline upper respiratory disease.
In particular, ISCAID notes that amoxicillin-clavulanate is:
Ineffective against Mycoplasma species
and is generally not the preferred drug for Chlamydia felis.
This is important because many feline respiratory infections are viral or involve organisms for which another antimicrobial may be more appropriate.
ANTIBIOTICS ARE NOT NEEDED FOR EVERY URI
Most uncomplicated feline upper respiratory infections are not automatically indications for antibiotics.
ISCAID recommends considering factors such as:
mucopurulent nasal discharge
fever
lethargy
decreased appetite
persistence or worsening of clinical signs
suspected bacterial involvement
The presence of sneezing, watery eyes, or clear nasal discharge alone does not necessarily indicate a bacterial infection.
URINARY TRACT INFECTIONS
Do not automatically use the respiratory dose as a universal dose for every infection.
ISCAID urinary-tract guidance lists amoxicillin-clavulanate as an option for bacterial urinary infections, but also emphasizes antimicrobial stewardship and recommends using the narrowest effective antibiotic.
Culture and susceptibility testing become particularly important with:
recurrent infections
complicated infections
previous antibiotic exposure
treatment failure
suspected resistant organisms
Always check the current ISCAID urinary guideline before establishing a urinary-treatment protocol.
CALCULATING A LIQUID DOSE
Always calculate in this order:
1. Determine the cat's weight in kilograms
Pounds ÷ 2.205 = kilograms
2. Calculate the required milligrams
Weight in kg × prescribed mg/kg = mg needed per dose
3. Check the medication concentration
The bottle or compounded preparation should state the concentration in:
mg/mL
4. Calculate the volume
Required mg ÷ concentration in mg/mL = mL per dose
IMPORTANT: CONCENTRATION MATTERS
Never write a protocol that simply says:
“Give 0.1 mL per pound.”
That instruction is incomplete unless the concentration is also specified.
For example:
A medication containing 62.5 mg/mL delivers twice as much drug per milliliter as one containing 31.25 mg/mL.
The same volume would therefore produce very different doses.
Every medication instruction should include:
Drug + concentration + mg/kg dose + mL dose + frequency
ABOUT CRUSHED TABLET SUSPENSIONS
A 62.5 mg amoxicillin-clavulanate tablet contains:
50 mg amoxicillin + 12.5 mg clavulanate
Crushing a tablet and adding water changes the medication into an informal suspension.
The calculated concentration depends on the final volume, not simply the amount of water poured into the container.
For example, if 62.5 mg of medication is brought to a final volume of 2 mL:
62.5 mg ÷ 2 mL = 31.25 mg/mL
At the ISCAID respiratory dose of 12.5 mg/kg, the required volume of that theoretical concentration would be:
12.5 mg/kg ÷ 31.25 mg/mL = 0.4 mL/kg
or approximately:
0.18 mL/lb
However, a crushed tablet mixed with water should not automatically be assumed to behave exactly like a commercially manufactured or professionally compounded suspension. Uniform distribution, final volume and stability need to be considered.
MEDICATION SAFETY
Before giving amoxicillin-clavulanate:
Confirm the cat's current weight.
Confirm the medication concentration.
Confirm the indication.
Check whether another antibiotic is more appropriate for the suspected organism.
Shake suspensions thoroughly before measuring.
Use an appropriately sized oral syringe for small doses.
Recalculate the dose when a growing kitten's weight changes substantially.
Seek veterinary evaluation promptly for cats with severe illness, respiratory distress, marked dehydration, neurologic signs, collapse, persistent high fever, or failure to improve.
PRIMARY VETERINARY SOURCES
International Society for Companion Animal Infectious Diseases (ISCAID)
Respiratory Disease
Antimicrobial Use Guidelines for Treatment of Respiratory Tract Disease in Dogs and Cats
Relevant feline amoxicillin-clavulanate recommendation:
12.5 mg/kg PO every 12 hours
Urinary Tract Disease
ISCAID Guidelines for the Diagnosis and Management of Bacterial Urinary Tract Infections in Dogs and Cats
Use the urinary guideline when treating suspected bacterial urinary disease rather than applying respiratory recommendations universally.
ISCAID Guidelines Library
Check the ISCAID Guidelines page periodically because recommendations are updated as veterinary evidence changes.
Last reviewed: September 2026
This reference is intended to summarize published veterinary guidance and support accurate medication calculations. It does not replace diagnosis of the underlying condition or organism.