Abstracts

Submitted by Rhea Amatya, Colorado State University

Incidental abdominal masses and nodules in older dogs – results of long-term follow-up in 190 dogs

Splenic, hepatic and/or adrenal nodules are commonly reported during ultrasound examination of the

abdomen in older dogs. While cytologic sampling or recheck ultrasound examinations to assess change

are commonly recommended, criteria for determining the level of concern for eventual progression of

these nodules have not been established. We sought to describe the long-term outcome in a group of

dogs in which abdominal visceral masses/nodules were identified during cancer screening. Dogs were

enrolled in a prospective study evaluating a novel cancer vaccine that followed clinically healthy,

middle-age to older dogs at average or higher risk for cancer development for up to five years. To meet eligibility criteria, dogs were deemed free of cancer and other systemic illnesses through physical exam, imaging, and clinicopathological tests. Using an automated keyword search, we identified 190 screening abdominal ultrasound reports that contained the words “mass” or “nodule.” We noted the location of the mass or nodule identified. We further categorized the cases as having no further investigation done (35), follow-up ultrasound done (59) and/or cytology done (73) and tracked whether the mass or nodule resulted in a cancer diagnosis. Of the 61 cases (37%) that were eventually diagnosed with cancer, 10 dogs (16%) were diagnosed with a cancer that had some likelihood of being associated with the mass or nodule found during the first ultrasound. 0 were deemed high likelihood, 3 were deemed medium likelihood, and 7 were deemed low likelihood. Overall, when a mass or nodule is found via ultrasound in the abdomen, either benign cytology or lack of progression on follow-up ultrasound 6 weeks later suggests a low risk of malignancy.