Evaluation of risk factors for sleep-disordered breathing in dogs

Abstract

Background: Brachycephalic dogs display sleep-disordered breathing (SDB). The risk factors for SDB remain unknown.

Objectives: To identify risk factors for SDB. We hypothesized that brachycephaly, increasing severity of brachycephalic obstructive airway syndrome (BOAS), excess weight, and aging predispose to SDB.

Animals: Sixty-three privately owned pet dogs were prospectively recruited: 28 brachycephalic and 35 normocephalic (mesaticephalic or dolicocephalic) dogs.

Methods: Prospective observational cross-sectional study with convenience sampling. Recording with the neckband was done over 1 night at each dog's home. The primary outcome measure was the obstructive respiratory event index (OREI). Body condition score (BCS) was assessed, and BOAS severity was graded for brachycephalic dogs.

Results: Brachycephaly was a significant risk factor for high OREI value (ratio of the geometric means 5.6, 95% confidence interval [CI] 3.2-9.9; P < .001) but aging was not (1.1, 95% CI 1.0-1.2; P = .2). Excess weight, defined as a BCS of over 5/9, (3.5, 95% CI 1.8-6.7; P < .001) was a significant risk factor. In brachycephalic dogs, BOAS-positive class (moderate or severe BOAS signs) was a significant risk factor (2.5, 95% CI 1.1-5.6; P = .03).

Conclusions and clinical importance: Brachycephaly decreases welfare in a multitude of ways, including disrupting sleep. Brachycephaly, increasing severity of BOAS and excess weight are risk factors for obstructive SDB.

Keywords: brachycephalic obstructive airway syndrome; obstructive respiratory event index; obstructive sleep apnea; sleep-disordered breathing.

FIGURE 1

Flow chart of the selection process for sleep recordings.

FIGURE 2

Occurrence of owner‐perceived signs of sleep‐disordered breathing, including restless sleep (A), snoring during sleep (B), sleeping sitting up (C), sleeping with toy in mouth (D), and apneic episodes during sleep (E), in dogs with a lower obstructive respiratory event index (OREI) of below 5 and higher OREI of over 5.

FIGURE 3

Occurrence of owner‐perceived signs of sleep‐disordered breathing, including restless sleep (A), snoring (B), sleeping sitting up (C), sleeping with toy in mouth (D), and apneic episodes during sleep (E), in normocephalic dogs and brachycephalic dogs, and in brachycephalic dogs with no or mild signs of brachycephalic obstructive airway syndrome (BOAS −) and brachycephalic dogs with moderate or severe signs of BOAS (BOAS +).

FIGURE 4

Scatter plot of snore percentage, as time spent snoring of total recording time, in all dogs with sleep recordings. Black data points are normocephalic dogs and green triangles and blue squares are brachycephalic dogs. Blue squares denote dogs with moderate or severe brachycephalic obstructive airway syndrome signs (BOAS positive class).

FIGURE 5

Scatter plot of obstructive respiratory event index (OREI) values in all dogs with sleep recordings. Black data points are normocephalic dogs and green triangles and blue squares are brachycephalic dogs. Blue squares denote dogs with moderate or severe brachycephalic obstructive airway syndrome signs (BOAS positive class).