Response rates in our study were similar for cases (65
percent) and controls (68 percent), and they were similar to
those reported in many case-control studies in human populations.
As with any case-control study, incomplete participation
by all eligible subjects may result in selection bias if
participation is influenced by both exposure and disease
status. In our population, study participation did not vary in
terms of an animal’s sex, reproductive status, year of birth,
or year of malignant lymphoma or renal failure diagnosis.
While cat owners who smoke may be less likely to participate
than those who do not, participation is unlikely to also
vary by disease diagnosis. To date, few studies have evaluated
lifestyle risk factors for chronic disease in companion
animals, so it is unlikely that owner participation would be
influenced by previous knowledge of an association between
household smoking and health in pets