Toxicity of aminoglycoside antibiotics

In cats, aminoclycosides cause vestibular damage followed in a few days by renal damage. The reverse is true in the dog, except that streptomycin causes vestibular damage prior to renal damage. To avoid toxicities, therapeutic doses of aminoglycosides should not be given longer than a week and they should be given cautiously in animals with renal impairment. Failure of the kidneys to eliminate aminoglycosides will result in very high blood levels, even with therapeutic doses, that can cause further renal and vestibular damage. The oral administration of aminoglycosides is seldom dangerous when normal therapeutic doses are employed. Although it is remote, the possibility exists that animals with renal impairment and intestinal obstruction may become intoxicated. Kanamycin is less nephrotoxic to dogs than neomycin and it is less destructive to the auditory nerve than vestibular damage than streptomycin. Gentamicin in cats is twice as toxic to the vestibular apparatus as streptomycin and more toxic to the cochlea than streptomycin or dihydrostreptomycin. Neomycin is more toxic than kanamycin, gentamicin, and streptomycin to both cats and dogs. Amikacin causes renal damage in dogs similar to other aminoglycosides. It also causes vestibular damage.