ABSTRACT
OBJECTIVE: To compare the radiographic appearance of small and large intestines of cats with various medical conditions and create a quantitative index for interpretation of intestinal diameters on radiographic views of the abdomen. DESIGN: Retrospective cohort study. ANIMALS: 74 cats that underwent abdominal radiography. PROCEDURES: Cats were assigned to 1 of 4 diagnosis categories: no gastrointestinal tract disease (n = 20), nonobstructive gastrointestinal tract disease (32), linear foreign body (LFB; 11), and small intestinal mechanical obstruction not caused by an LFB (11). Abdominal radiographs were evaluated without knowledge of history or diagnosis. Maximum and minimum external small intestine diameter (SID) and colon diameter (CD) were compared; dorsoventral and mediolateral measurements of the cranial end plate of L2 (VEL2) and L5 vertebrae were compared. Dorsoventral height of VEL2 from lateral radiographic views was used to determine maximum-SID:VEL2 and maximum-CD:VEL2 ratios. Gas patterns were evaluated. RESULTS: Nonobstructive gastrointestinal tract disease was more likely than obstruction until a maximum-SID:VEL2 ratio > 2.0. At a maximum-SID:VEL2 ratio of 2.5, probability of a disease not related to the intestinal tract was < 4%. At a maximum-SID:VEL2 ratio of 3.0, probability of a mechanical intestinal obstruction was > 70%. When the maximum-CD:VEL2 ratio was 2.0, probability of LFB was 50%; as the maximum-CD:VEL2 ratio increased beyond 2.0, likelihood of LFB decreased. Both gas pattern and CD correlated with diagnosis category. CONCLUSIONS AND CLINICAL RELEVANCE: Normalizing ratios of maximum-SID:VEL2 and maximum-CD:VEL2 obtained from measurements on lateral radiographic views of the abdomen in cats were related to diagnosis category.
