Amikacin blood level in dogs and cats
Amikacin is an antibiotic of the aminoglycoside group, with the broadest range of bacteria in that group. Aminoglycosides can damage the kidneys, so the vet may measure the drug in the blood: a peak sample shows whether the level is high enough to act on the bacterium, and a trough sample shows whether the drug clears before the next injection. The result is read together with the sampling time and the kidney tests.
What it shows
Aminoglycosides build up in the cells of the kidney tubules, and too much of this build-up damages those cells. Measuring the drug in the plasma is described as the best way for the vet to adjust the plan for a particular animal, because the same regimen gives different levels in different patients.
Two kinds of sample are used. The peak is taken after the drug has spread into the tissues — about an hour after it is given; a sample at about 1.5–2 hours is described for judging effect. For the peak, the target is set in relation to the MIC — the lowest concentration that stops the growth of the particular bacterium in the lab — and is about 10–12 times that value. The trough is taken just before the next administration; if only one sample is taken to check safety, it is the trough. Aminoglycosides are usually given once a day partly for safety: a long interval lets the level fall.
Higher than reference — what it may be a sign of
- Trough above the target. The drug has not cleared by the time of the next administration as expected. This raises the concern about the kidneys, and the vet looks at kidney function and urine.
- Risk factors for kidney injury. Age, already reduced kidney function, dehydration, acidosis, low magnesium, severe sepsis and some other medicines (for example certain diuretics) make kidney damage more likely.
- Timing of the sample. A “trough” taken too early after the injection gives a higher number than a true trough.
A result is not a signal to change anything at home: the vet decides what to do with it.
Lower than reference
A low trough is the expected, wanted result. A peak below the target for the bacterium may mean the level is not high enough to act well on the infection; the vet reads it together with the culture result and how the animal is doing. A peak taken late, after the level has already started to fall, also looks lower than it is.
Look at together with
- Urinalysis — early kidney changes from aminoglycosides show up in the urine first: more urine, less concentrated urine, protein, casts and enzymes in the urine, and a higher fractional excretion of sodium. Sugar in the urine with normal blood glucose (see glucose in urine) and granular casts can point to tubular injury.
- Creatinine and urea — rise later than the urine changes.
- Magnesium and other electrolytes — low magnesium is one of the risk factors.
Units and conversion
Amikacin is reported in µg/mL; some references write the same unit as mcg/mL. In the app each row keeps the unit printed on the form, and the chart shows µg/mL.
Reference range
The target values are on your lab’s form or in the vet’s request. For amikacin it is not a range of healthy animals: the peak target depends on the bacterium, and the trough target is a safety limit, so the target is set by the vet. For aminoglycosides in general, the Merck Veterinary Manual gives a safety guide: a trough generally below 2 µg/mL. Early signs of kidney damage can be found in 3–5 days, with clearer signs in 7–10 days, and no kidney test is sensitive enough to stop damage that is already under way once it is found — which is why the urine is watched from the first days.
Cats and dogs
Cats are particularly sensitive to the effect of aminoglycosides on the balance organ in the inner ear, although this is unlikely at the usual blood levels after injection. Signs of balance damage are flickering eye movements and incoordination. Kidney monitoring in cats follows the same idea as in dogs: urine first, then creatinine.
In dogs, kidney damage is the main concern, read through urine changes, creatinine and urea. Aminoglycosides can also damage hearing, and that damage is permanent; the reference notes that this matters especially for working dogs that depend on hearing, such as guide dogs. Casts in urine are shed unevenly, so one sample without casts does not rule out kidney injury.
Add a lab form — Pet Tracker Space recognises the lines, keeps the form’s units and draws each indicator over time with your lab’s reference band.
Sources
This page explains what a lab value means. It is not a diagnosis and not a substitute for your veterinarian — only they can interpret results for your pet.