Associations between sex, body weight, age, and ultrasonographically determined adrenal gland thickness in dogs with non-adrenal gland illness.

OBJECTIVE To determine whether body weight, age, or sex was associated with ultra-sonographically determined adrenal gland thickness (AT) in dogs with nonadrenal gland illness. DESIGN Retrospective cross-sectional study. ANIMALS 266 dogs (22 sexually intact and 119 castrated males and 19 sexually intact and 106 spayed females representing 12 breeds) with non-adrenal gland illness. PROCEDURES Thickness of the caudal pole of the left and right adrenal glands was measured on longitudinal ultrasonographic images. Dogs were stratified into age and body weight categories to investigate associations with AT. RESULTS AT was significantly lower in dogs that weighed <= 12 kg (26.4 lb) than in dogs that weighed > 12 kg and left AT increased with age. Both left and right AT were larger in male than in female dogs that weighed > 12 to <= 20 kg, and left AT was larger in male than in female dogs that weighed > 20 to <= 30 kg. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that body weight, age, and sex were significantly associated with AT, indicating that these variables should be considered when evaluating AT in dogs with non-adrenal gland illness and when developing reference intervals for AT in dogs. Further, findings indicated that dogs with non-adrenal gland illness that weigh <= 12 kg should have an AT no greater than 0.62 cm, whereas dogs that weigh > 12 kg should have an AT no greater than 0.72 cm.