Resumen de Prevalence of deafness and association with coat variations in client-owned ferrets
Objective—To evaluate the prevalence of congenital sensorineural deafness (CSD) and its association with phenotypic markers in client-owned ferrets.
Design—Epidemiological study.
Animals—152 healthy European pet ferrets.
Procedures—Brainstem auditory evoked response tests were recorded in ferrets during general anesthesia. Phenotypic markers such as sex, coat color and pattern, coat length (Angora or not), and premature graying trait were assessed.
Results—Overall, 44 of the 152 (29%) ferrets were affected by CSD; 10 (7%) were unilaterally deaf, and 34 (22%) were bilaterally deaf. There was no association between CSD and sex or Angora trait, but a strong association between CSD and white patterned coat or premature graying was identified. All panda, American panda, and blaze ferrets were deaf.
Conclusions and Clinical Relevance—The ferrets in this study had a high prevalence of CSD that was strictly associated with coat color patterns, specifically white markings and premature graying. This seemed to be an emerging congenital defect in pet ferrets because white-marked coats are a popular new coat color. Breeders should have a greater awareness and understanding of this defect to reduce its prevalence for the overall benefit of the species. (J Am Vet Med Assoc 2014;244:1047–1052) Congenital sensorineural deafness in pet ferrets is a controversial subject among breeders and owners. It seems to be associated with white or white-marked coats as it is in other species.1,2,a Coat color-related sensorineural deafness has been described in numerous species, including cats, dogs, horses, mink, mice, guinea pigs, llamas, and alpacas.3–5 A common phenotype for these animals, regardless of the species, is that they have substantial white or merle- or dappled-colored coats.5,6 Deafness is linked to failure of migration or maturation, premature death, or dysfunction of neural crest melanocytes in the inner ear, in a region of the cochlea known as the stria vascularis.5 There are many theories and misconceptions about this subject in ferrets, including the notion that other neural crest defects are associated with white markings and deafness. However, it appears that they are not confirmed by scientific studies and to the authors' knowledge, the prevalence and inheritance of CSD in ferrets are unknown.
Traditional clinical tests to assess hearing are difficult to perform in active animals such as ferrets and are not appropriate for detection of unilateral deafness. The BAER test has been used successfully to identify deafness in ferrets that were thought to have normal hearing. This electrodiagnostic test provides information about the functional state of the peripheral and brainstem component of the auditory portion of the nervous system and can be defined as the electrical response of the auditory pathway to a series of auditory stimuli.7 This procedure can be easily performed in a clinical setting in ferrets as a screening test before adoption.b Brainstem auditory evoked response testing is an objective method for the diagnosis of CSD and can potentially be used in a program for screening and selecting breeding stock.
The objectives of the study reported here were to evaluate the prevalence of CSD and its association with phenotypic markers in client-owned ferrets by use of the BAER test. The hypothesis was that CSD is associated with certain coat colors or patterns in ferrets.
