Since the discovery of the first aminoglycoside (streptomycin) in 1944 3 and, subsequently, other compounds of this class (gentamicin in 1963) 4, they have been widely popular due to their broad antibacterial spectrum, non-allergenic characteristics, and inexpensive cost. Gentamicin is one of the aminoglycosides, a class of antibiotics which is effective mainly against gram-negative bacteria.
This article will address the potential ototoxicity of cisplatin, gentamicin, furosemide, and related compounds, drawing from laboratory animal studies and human clinical trials, which have been well documented over decades of research and experience. However, with increasing duration of chemotherapy as might be needed for cancer or with confounding factors such as aging the impediments can become so severe as to affect gait and balance or even be a risk to life if an approaching danger such as a car cannot be heard. As a result, animals with auditory or vestibular deficits may function reasonably well in a familiar environment, an adaptation that is likewise observed in humans. Verbal commands are frequently accompanied by body language that helps their interpretation in the presence of a compromised hearing, and visual cues and some inherent plasticity of the vestibular system will hide small effects on balance. Subtle changes in hearing will go largely unnoticed by pet owners because these animals either will rely more on or compensate with their other senses. The incidence of therapy-linked ototoxicity in domestic dogs and cats is difficult, perhaps impossible, to establish. Finally, in considering potential causes of hearing loss in animals, environmental factors should not be overlooked, such as advanced age and even exposure to noise in large kennels. It is of interest to note that some of these therapeutics also exhibit renal toxicity, as has been documented for aminoglycosides and cisplatin, as well as some non-steroidal anti-inflammatory agents. Some ototoxic potential might also be associated with occasionally or rarely used drugs such as the anthelmintic arsenical melarsomine and the antibiotic erythromycin.
Of potential concern in veterinary practice are primarily the antibacterial aminoglycoside antibiotics gentamicin and amikacin, the anti-cancer agent cisplatin, and loop diuretics like furosemide, all of which will be discussed in this article. arsenicals, mercurials), drugs that only cause a temporary effect on hearing (e.g., salicylates), and drugs in current use associated with a significant incidence of permanent hearing loss (aminoglycosides, cisplatin). In human medicine, the list includes drugs of past interest (e.g. Only subsequently did laboratory experiments establish animal models from which further insight into toxic mechanisms was gained and which can be used to delineate safe or protective treatments.Ī surprisingly wide variety of drugs are potentially ototoxic, varying in chemical structure and therapeutic targets ( Table 1). 1 It is notable that these side effects were all first discovered in humans, including the landmark discoveries of auditory and vestibular toxicity (ototoxicity) of aminoglycoside antibiotics and cisplatin in the 20 th century. In particular, the knowledge that some agents have the potential to adversely affect our senses of hearing and balance has a history going back at least a thousand years. The awareness that therapeutic treatments sometimes impose undesirable side effects ranging from minor inconveniences to death is probably as ancient as the practice itself of treating ailments with herbs and drugs.