Epidemiological associations between brachycephaly and upper respiratory tract disorders in dogs attending veterinary practices in England

Table 1 Demographic comparison between two breed groups of 600 extreme brachycephalic (Bulldog, French Bulldog, Pug) and 600 moderate and non-brachycephalic dogs (moderate: Yorkshire Terrier, non-brachycephalic: Border Terrier and West Highland White Terrier) attending primary-care veterinary practices in England (200 dogs of each breed type)

Variable	Category	Extreme brachycephalic No. (%)	Moderate and non-brachycephalic No. (%)	Overall	P-value
Sex/neuter	Female entire	236 (40.0)	160 (26.7)	396 (33.3)	<0.001
	Female neutered	43 (7.3)	115 (19.2)	158 (13.3)
	Male entire	269 (45.6)	211 (35.2)	480 (40.3)
	Male neutered	42 (7.1)	114 (19.0)	156 (13.1)
Insured	Insured	103 (17.2)	159 (26.5)	262 (21.8)	<0.001
	Not insured	497 (82.8)	441 (73.5)	938 (78.2)
Bodyweight (kg): Median (IQR^a, range)		12.4 (9.5–24.2, 1.6–41.0)	8.7 (5.9–10.5, 1.5–20.7)	9.7 (7.6–12.2, 1.5–41.0)	<0.001
Age (years) at final EPR^b: Median (IQR^a, range)		1.5 (0.4–3.5, 0.0–14.0)	5.5 (2.5–10.2, 0.0–18.2)	3.1 (1.0–7.1, 0.0–18.2)	<0.001
Time in study (years): Median (IQR^a, range)		0.2 (0.0–1.1, 0.0–4.3)	0.9 (0.0–2.4, 0.0–5.0)	0.4 (0.0–1.8, 0.0–5.0)	<0.001