Hearing disorders in cats: Classification, pathology and diagnosis

Abstract

Practical relevance: Auditory function is a sense that is central to life for cats - being important in situational awareness of potential predators, pursuit of prey, and for communication with conspecifics, humans and other species. Deafness in cats is most frequently the result of a genetic disorder, strongly associated with white fur and blue eyes, but may also result from acquired causes such as advancing age, ototoxic drugs, infection, environmental noise and physical trauma. Deafness can be sensorineural, where there is loss of cochlear hair cells, or conductive, where sound is muffled on its way to the inner ear. Clinical challenges: Establishing whether a cat is deaf can be difficult as behavioral testing of hearing is subjective and does not reliably detect unilateral deafness. Brainstem auditory evoked response testing is an objective measure but is limited in its availability. Currently, sensorineural deafness is irreversible because no treatments are available to restore lost hair cells. Conductive hearing loss can usually be treated, although full hearing recovery following otitis media may take weeks as the body clears the middle ear of debris. Evidence base: The author draws on the published literature and his extensive research on clinical aspects and molecular genetics of deafness, principally in companion animals, to review types and forms of deafness in cats. He also discusses current diagnostic approaches and provides brief advice for managing cats with hearing loss.

A genome-wide association study of deafness in three canine breeds

“…However, the inheritance of this deafness does not follow simple Mendelian inheritance patterns (reviewed by [1]). Pigment-associated hereditary deafness is observed in numerous other species, most frequently recognized in blue-eyed white cats [1,3,8,9].…”

Comparison of Age-Related Pigmentary Changes in the Auditory and Vestibular Systems Within Mouse and Human Temporal Bones

“…A primary role for OHC loss in presbycusis is supported by a more recent human temporal bone study that used statistical modeling and immunolabeling to more precisely measure neural degeneration (Wu et al, 2020). However, other human temporal bone studies have pointed to SV degeneration as a principal mechanism of age-related hearing loss (Schuknecht et al, 1974), and numerous animal studies have implicated the SV in age-related hearing loss (Strain, 2004(Strain, , 2017Ohlemiller et al, 2006Ohlemiller et al, , 2009. Part of this discrepancy may be explained by the fact that human temporal bone studies are limited to histopathologic correlations and can only measure atrophy of the SV, rather than function.…”

“…In humans Waardenburg syndrome and Tietz syndrome cause congenital deafness and hypopigmentation of the hair, eyes, and skin (Milunsky, 2017). Pigmentary disorders have similarly been associated with congenital deafness in dogs and cats (Strain, 2004(Strain, , 2017. Conversely, differential levels of pigmentation have been hypothesized to alter susceptibility to noise-induced hearing loss and presbycusis (Bunch and Raiford, 1930;Ardiç et al, 1998;Ishii and Talbott, 1998;Murillo-Cuesta et al, 2010;Lin et al, 2011Lin et al, , 2012Sun et al, 2014), and potentially vestibular dysfunction (Erbele et al, 2016).…”

Investigations on the incidence of deafness in Van cats and its distribution by eye color

“…In cats deafness is often caused by a genetic disorder. It has long been known that congenital deafness is common in white cats with blue eyes (24). Owing to genetic factors Van, Ankara and other white cat breeds show the presence.…”