2-Year-Old FS Mixed Breed

Signalment & History

  • Patient presents for lethargy intermittent vomiting beginning 36 hours ago. Standard 3-view abdominal radiographs are taken.


  • In the mid ventral abdomen, within the lumen of a small intestinal segment, there is a 3.5 cm metallic paper clip.  In the mid right abdomen, best seen on left lateral and VD radiographs,  a small intestinal segment is moderately enlarged by a large amount of heterogenous soft tissue opaque material with curvilinear, faint gas striations.
  • There are 2 populations of small intestine, with the largest:smallest small intestinal diameter ratio measuring 2.4, and the small intestinal diameter to L5 ratio measuring 3. These ratios are suggestive of mechanical obstruction.
  • Within multiple small distal segments there are small, round and oval, centrally located, contiguous gas bubbles.


  • This patient was diagnosed with a small intestinal mechanical obstruction via a corn cobb based on the presence of two populations of small intestines, measuring greater than 1.6 times the height of the mid-body of L5.


  • Small intestinal foreign material (soft tissue opaque material and paperclip) with evidence of mechanical obstruction.
  • Stomach is empty and attributed to recent vomiting just before taking the radiographs.
  • In dogs, there are two useful measurements you can make to decide if a loop of bowel is abnormally dilated:
    • SImax:L5 – A ratio of the maximal diameter of the dilated small intestinal segment compared to the narrowest height of the body of L5 > 2.4 is strongly suggestive for mechanical obstruction.
    • SImax:SImin – The ratio of the diameter of the largest loop of small intestine with the smallest > 3.4 is strongly suggestive for mechanical obstruction.
    • Alternatively, an SImax/L5 ≤ 1.4 and SImax/SImin ≤ 2 were strongly suggestive of NO obstruction.
  • Sometimes it is difficult to differentiate the questionable enlarged small intestinal segment from a normal part of the colon. In order to try to solve this problem, a pneumocologram (negative contrast study) or barium enema (positive contrast study) can be performed.
  • It’s also important to remember not to get too distracted by gas in the small intestine. Sometimes the less obvious, fluid filled intestinal loops are the dilated loops while gas-filled loops remain normal. “Two populations of bowel” refers strictly to size, NOT to contents.


  • Finck, C., et al (2014). Radiographic diagnosis of mechanical obstruction in dogs based on relative small intestinal external diameters. Veterinary Radiology & Ultrasound, 55(5), 472–479.