Colic Diagnosis - Abdominal Ultrasound

Ultrasonographic evaluation of the abdomen is extremely useful in characterizing certain components of the disease process in the foal or horse with colic. The findings of the abdominal ultrasound can distinguish surgical and medical colic patients. It is a very useful non-invasive diagnostic tool and can be used to guide other techniques such as abdominocentesis. It can be carried out trans-abdominally or trans-rectally. The latter scenario is useful for confirming andormalities palpated on prior rectal examinations.

It is important that the veterinarian is confident with the normal abdominal ultrasound of the horse in order to detect significant abnormalities. The amount and character of free abdominal fluid can be determined, as well as the determination of a specific place for safe, high-yield abdominocentesis. The appearance of intestine including distension of the lumen, increased wall thickness and motility (or lack thereof, often seen as sedimentatioon of digesta)indicate a degree of intestinal comprimise and can be extremely important in the decision for surgical or medical therapy. The large colon and cecum can be evaluated for wall thickness (particularly useful in cases of right dorsal colitis), fluidy contents (colitis/diarrhea), and sometimes displacement. The presence of mesenteric vessels associated with the large colon is generally associated with displacement. The normal anti-mesenteric vessels of the cecum can be used to trace its course. Ventral displacement of the spleen with obscuring of the left kidney is associated with nephro-splenic displacement. Visualization of sacculated large bowel immediately ventral to the liver or spleen, or non-sacculated large bowel in the ventral abdomen suggests displacement. The stomach can be evaluated for fluid distension and abnormalities of the wall. Significant fluid distention of the stomach should indicate that nasogastic decompression is needed. Abdominal ultrasound is useful in detecting diaphragmatic or inguinal herniation. Masses of the spleen, kidneys and liver can be demonstrated and may be incidental findings or causes of false colic.

References

• Meuller E, Moore J. N, (2008) Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures, 3rd Edition, Eds Orsini J. A, Divers T.J, Saunders Elsevier, pp 39 - 44
• Rose R.J, Hodgson D.R (2000) Examination of the Alimentary Tract, Alimentary Tract, Manual of Equine Practice, 2nd Edition, Saunders Elsevier, pp 287 - 288