White, fluffy fur, and striking blue eyes—cats and kittens with this color combination are undoubtedly beautiful, and may have you hooked the moment you lay eyes on them. But did you know there is a hidden health issue associated with this distinctive look?
We’ll discuss congenital sensorineural deafness, a hereditary condition that causes hearing loss in white, blue-eyed cats. We’ll also cover prevalence of deafness, as well as diagnosis, treatment, and prevention of the condition. Let’s get to it.
What Is Congenital Sensorineural Deafness?
Congenital sensorineural deafness (CSD) is a well-known condition affecting white, blue-eyed cats that has been studied since the 19th century. This condition is hereditary, meaning that it is determined by genetic factors, and may be passed down from parents to offspring. CSD specifically affects cats that possess the autosomal dominant pigment gene W. Deafness in affected cats may either be unilateral (affecting one ear) or bilateral (affecting both ears).
How Does CSD Occur?
In cats with the dominant W pigment gene, white skin, hair, and blue eyes occur as a result of melanocyte (pigment-producing cell) suppression. If the W gene acts strongly, it also suppresses melanocytes in the stria vascularis (a component of the cochlea), which leads to strial degeneration and cochlear hair loss in the inner ear. This ultimately leads to cochleosaccular neuronal degeneration and subsequent deafness that develops approximately 1–3 weeks after birth.
Are All White Cats With Blue Eyes Affected?
While deafness is commonly seen in white cats with blue eyes, not all cats with this specific coloring will be affected. From studies of mixed-breed white cats, the following prevalence of deafness was noted:
A recent study of purebred kittens in the United Kingdom found the following with regards to the prevalence of CSD:
This study also noted differences in the breed-specific prevalence of CSD. The prevalence of deafness was noted to be higher (greater than 40%) in solid white Norwegian Forest, Maine Coon, and Turkish Vankedisi kittens, and lower (less than 17%) in Russian, Persian, and Devon Rex kittens.
How Is Deafness Diagnosed In Cats?
Deafness may be difficult to diagnose in young kittens, or in cats kept in groups, as these animals’ reactions will often mimic those of the others in their group. To evaluate for deafness, a kitten should be observed individually, after 3–4 weeks of age, when responses to sounds become more predictable. The following signs may indicate that your kitten or cat may be affected by hearing loss:
If you have any concerns that your white, blue-eyed feline may be deaf, a visit to your veterinarian is recommended. They will perform an examination and observe your cat’s response to various sound stimuli in the exam room. While this may provide a general idea of your cat’s ability to hear, the most reliable method of diagnosing deafness is with brainstem auditory evoked response (BAER) testing at a referral center. BAER screening is a non-invasive, electro-diagnostic test that can be used to diagnose CSD in cats greater than 20 days of age.
Treatment for CSD
There is unfortunately no effective treatment for congenital, hereditary deafness in cats. While sensorineural deafness cannot be reversed, there is thankfully no evidence that deaf animals suffer discomfort or pain from the condition. Many cats affected by deafness are still able to live otherwise full, long lives.
Prevention of CSD
At present time, there is no DNA testing available to identify genetic carriers of deafness in cats. To reduce the prevalence of this condition, BAER testing and selective breeding should be strongly considered for cats with commonly-affected phenotypes.
In summary, while not all blue-eyed white cats are deaf, deafness is commonly noted in cats with these striking physical characteristics—and is a phenomenon that has been noted for centuries. While prevention and treatment options are unfortunately limited, affected felines can still be happy, healthy, and engaged members of your family.
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