Brachycephalic obstructive airway syndrome (BOAS) is an upper airway obstruction
that was considered the most severe disorder identified according to
the Generic Illness Severity Index for Dogs. The aim of this master thesis was
to investigate the phenotypic variance correlated to BOAS in the Swedish
population of four brachycephalic breeds; English Bulldog, French Bulldog,
Pug and Boston Terrier and discuss their welfare implications. The project
consisted of two parts; one inventory and one survey. The inventory consists
of conformational description of the four brachycephalic breeds and the survey
was to investigate the BOAS related problems in the same breeds and
their owner’s perspective of health and welfare. The conformational risk factors
correlated to BOAS found in this study were snout length and craniofacial
ratio for French Bulldogs, snout length, chest girth, neck length, sternum
length and craniofacial ratio for English Bulldogs and none for either Pugs or
Boston Terriers. According to the survey noisy breathing and heat intolerance
were the most common BOAS-related problems for all the four breeds in this
study. The conclusion of the study was that there was enough phenotypic variance
to improve the BOAS problem for both French Bulldogs and English
Bulldogs. For Boston Terriers the BOAS problem was not severe enough in
this study to get a result and for the Pugs the phenotypic variance is too small.
For the welfare aspect this study showed that BOAS is a welfare problem and
that there was a normalization for some of the problems connected to BOAS
for English Bulldogs, French Bulldogs and Pugs
