Abdominal ultrasound is a great first imaging modality in many patients, however, it has been shown to be less sensitive than abdominal CT in some patients weighing > 25 kg. In a study, abdominal CT found more clinically and equivocally relevant changes than abdominal ultrasound.
Based on our clinical experience, abdominal ultrasound can still be extremely useful in dogs greater than this weight, depending on the clinical disease/pathology suspected. However, the owner must be made aware that although ultrasound may find significant abnormalities that would explain the patient’s clinical signs, there is a risk of missing other clinically relevant findings and therefore an abdominal CT may still be required as the next step.