Hereditary Inner-Ear Abnormalities in Animals: Relationships With Human Abnormalities

Inner ear histopathology in “nervous Pointer dogs” with severe hearing loss

“…Indeed, the spiral ganglion cell count was found normal in the 82 day-old puppies but spiral ganglion neuron loss was already observed in 131 day-old puppies and massive neuronal loss was observed in at least two 148 dayold puppies. In the progressive sensorineuronal degeneration previously described in dogs as well as in other species, the retrograde neuronal degeneration is usually slow and a time lag of several months to years separates CortiÕs organ degeneration and spiral ganglion neuron loss (Igarashi et al, 1972;Mair, 1976;Steel and Bock, 1983;Nadol et al, 1989;Wilkes and Palmer, 1992;Niparko and Finger, 1997;Miura et al, 2002). Our observation differed from this description in that the spiral ganglion neurons disappeared early after the CortiÕs organ degeneration in Pointer cross-puppies.…”

Cochlear Synaptic Development and Morphology in a Genetically Induced Type of Progressive Hair Cell Degeneration

“…Three major categories of inner ear abnormalities have been defined in the mouse: morphogenetic, cochleosaccular and neuro epithelial (degenerative). Similar conditions appear to exist in man [2], The primary site of gene action is unknown in most of these mutants. In the morphogenetic mutants it is evident that the genes exert their influence already in embryonic life, and most likely they do so via a primary neural tube defect.…”

Postnatal maturation of the dog stria vascularis— an immunohistochemical study

“…In this defect, the cochlear duct is collapsed, the stria vascularis and organ of Corti are degenerated, the tectorial membrane is abnormal, and the sacculus is usually collapsed. This type of deafness is reported in several mammalian species, including dogs and humans (Steel and Bock, 1983; Steel and Harvey, 1992; Schucknecht, 1993; Strain, 1996; Hardisty et al, 1998). In humans, the best documented cochleosaccular entities are the Waardenburg's syndromes (Cable et al, 1994; Hardisty et al, 1998), which are associated with pigmentation defects, as in dogs.…”