Relationship between hearing, cognitive function, and quality of life in aging companion dogs

Abstract

Background: Elderly people with presbycusis are at higher risk for dementia and depression than the general population. There is no information regarding consequences of presbycusis in dogs.

Objective: Evaluate the relationship between cognitive function, quality of life, and hearing loss in aging companion dogs.

Animals: Thirty-nine elderly companion dogs.

Methods: Prospective study. Hearing was evaluated using brainstem auditory evoked response (BAER) testing. Dogs were grouped by hearing ability. Owners completed the canine dementia scale (CADES) and canine owner-reported quality of life (CORQ) questionnaire. Cognitive testing was performed, and cognitive testing outcomes, CADES and CORQ scores and age were compared between hearing groups.

Results: Nineteen dogs could hear at 50 dB, 12 at 70 dB, and 8 at 90 dB with mean ages (months) of 141 ± 14, 160 ± 16, and 172 ± 15 for each group respectively (P = .0002). Vitality and companionship CORQ scores were significantly lower as hearing deteriorated (6.6-5.4, 50-90 dB group, P = .03 and 6.9-6.2, 50-90 dB group, P = .02, respectively). Cognitive classification by CADES was abnormal in all 90 dB group dogs and normal in 3/12 70 dB group and 11/19 50 dB group dogs (P = .0004). Performance on inhibitory control, detour and sustained gaze tasks decreased significantly with hearing loss (P = .001, P = .008, P = .002, respectively). In multivariate analysis, higher CADES score was associated with worse hearing (P = .01).

Conclusions and clinical importance: Presbycusis negatively alters owner-pet interactions and is associated with poor executive performance and owner-assessed dementia severity.

Keywords: CCDS; canine cognitive dysfunction syndrome; cognitive testing; dementia; presbycusis.

FIGURE 1

Representative brainstem auditory evoked response tracings of a dog. There is an absent wave V at 50 dB (A), however, wave V is identifiable at 70 dB (B) and 90 dB (C).

FIGURE 2

Box plots showing Canine Owner‐Reported Quality of Life of the (A), vitality and (B), companionship domain scores for dogs in the 50, 70, and 90 dB hearing groups. The horizontal line within the boxplot represents the median, the ends of the box represent the interquartile range, the upper and lower whisker extend 1.5 × interquartile range from the top and bottom of the box. Lines labeled with * denote a significance of P < .05 between hearing group and lines labeled with ** denote a significance of P < .01 between hearing groups.

FIGURE 3

Clinical stage of cognitive dysfunction syndrome as assessed by Canine Dementia Scale for dogs in each hearing group. Green stacked bars show the relative count of dogs that were identified as normal, blue stacked bars show the relative count of dogs that were identified as mildly affected, red stacked bars show the relative count of dogs that were identified as moderately affected, and purple stacked bars show the relative count of dogs that were identified as severely affected.

FIGURE 4

Box plots showing results of testing of (A), inhibitory control, and (B), detour in the 50, 70, and 90 dB hearing groups. The horizontal line within the boxplot represents the median, the ends of the box represent the interquartile range, the upper and lower whisker extend 1.5 × interquartile range from the top and bottom of the box. Lines labeled with * denote a significance of P < .05 between hearing groups and lines labeled with ** denote a significance of P < .01 between hearing groups.

FIGURE 5

Box plots showing results of testing of sustained gaze, in the 50, 70, and 90 dB hearing groups. The horizontal line within the boxplot represents the median, the ends of the box represent the interquartile range, the upper and lower whisker extend 1.5 × interquartile range from the top and bottom of the box. Lines labeled with * denote a significance of P < .05 between hearing groups and lines labeled with ** denote a significance of P < .01 between hearing groups.