Contributors: Barbara J Watrous

 Species: Canine   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading


  • Use of positive, negative or a combination of contrast agents to highlight the gastric lumen.


  • Identification of the position of the stomach, eg in ascites or if suspect gastric displacement, eg diaphragmatic hernia Diaphragm: traumatic hernia.
  • Investigation:
  • Assessment of lumen size and gastric axis if stomach not visible on plain films.


  • Relatively simple procedure in most patients.
  • Non-invasive.


  • Often difficult to assess subtle mucosal lesions.
  • Not very accurate for assessment of motility disorders.

Technical Problems

  • Difficult to interpret if not familiar with normal appearance.

Alternative Techniques

  • Gastric ultrasonography (should precede contrast radiography if performed on same day).
  • Gastroscopy Gastroscopy (should precede contrast radiography if performed on same day,although drugs used for restraint will affect gastric motility).
  • Scintigraphy.
  • Barium impregnated polyurethane spheres (BIPs).

Time Required


  • Dependent upon method of restraint.
  • Food withheld for 12-24 hours (may not be required if animal is inappetant).
  • Enemas required ideally night before but not within 2-3 hours of procedure.
  • May need to withhold food for 24 hours if delayed gastric emptying.
  • If considering endoscopy Gastroscopy this should be performed before contrast radiography.

Decision Taking

Criteria for choosing test

  • Is the examination appropriate?
  • Can you make the diagnosis without it?
  • Will your management of the case be affected by the outcome of the examination?

Risk assessment

  • If suspect gastrointestinal tract rupture it is theoretically safer to use water-soluble contrast agents:
    • Gastrointestinal tract rupture requires surgical intervention and abdominal lavage so leakage of contrast agents may not be a particular problem and iodine-based agents may exacerbate hypovolemia in a shocked animal by drawing fluid into the GI tract.


Materials Required

Minimum equipment

  • X-ray machine.
  • Cassette.
  • Processing facilities.
  • Protective clothing (lead apron) for radiographer.
  • Positioning aids (sandbags, cradle and ties).
  • Method of labelling film.
  • Large syringe.
  • Means of keeping mouth open for stomach tubing, eg inner part of bandage roll.
  • Stomach tube.

Ideal equipment

  • Ability to process films during procedure so that repeat radiographs can be taken during course of study if required.
  • High output x-ray machine.
  • High definition screen.
  • Grid for examination of large dog.
  • Mouth gag.

Minimum consumables

  • Radiographic film.
  • Contrast agent.
  • Water-soluble lubricant for stomach tubing.


Dietary Preparation

  • Withhold food 12-24 hours prior to procedure.


  • Sedation.
  • Low dose of acepromazine Acepromazine maleate (0.05-0.1 mg/kg) has minimal effect of gastrointestinal motility and transit times.
    Avoid diazepam Diazepam , xylaxine Xylazine , barbituates, opoids and parasympathic drugs, eg atropine Atropine , as they have been shown to delay gastric emptying.
  • If performing negative or double contrast studies gastric motility can not be assessed so effect of sedation is unimportant.

Other Preparation

  • Administer cleansing enema Enema the night before procedure and 2-3 hours before procedure if necessary.
  • Glucagon has been used to promote gastric relaxation for double-contrast gastrography, but is very expensive.



Step 1 - Control films

  • Plain abdominal radiographs Radiography: abdomen should be obtained prior to contrast study to:
    • Check exposure settings and processing.
    • Confirm animal adequately prepared, ie colon empty.
    • Confirm positioning adequate.
    • Confirm diagnosis not apparent without contrast study.
    • Identify radiopaque foreign bodies which may be masked by barium.
  • Premeasure stomach tube against animal from mouth to stomach, and mark on tube length required to reach stomach.

Step 2 - Selection of contrast agent

  • Positive:
    • Liquid barium (10 ml/kg,15% W/W).
    • Iodine-based contrast (2.2 ml/kg, 10% W/W) (hyperosmolar and may cause hypovolemia and shock. Expensive).
    • Suitable for assessing position of stomach, wall thickness and gastric emptying.
    • May mask foreign bodies.
    • Can be used for follow through investigation of small intestine.
  • Negative:
    • Air (4-8 ml/kg).
    • Carbon dioxide/air.
    • Suitable for assessing position of stomach and identifying foreign bodies and gross wall thickening.
  • Double contrast: provides best information on mucosal detail.

Step 3 - Insert stomach tube

  • Insert premeasured length of stomach tube to level of stomach.
  • Inject small amount of water/saline to ensure tube correctly placed in stomach and not respiratory tract.

Core Procedure


Step 1 - Instil contrast agent

  • Inject (negative or positive) contrast in sufficient quantity to distend stomach.
    Tendency to underfill stomach in most cases.
  • Dose 5-12 ml/kg (with reduced dose rate for larger dogs).
Double contrast gastrography
  • Administer 1-3 ml/kg of barium - lower doses for larger dogs.
  • Roll animal through 360° then restomach tube and inflate stomach with air/carbon dioxide 5-10 ml/kg.
  • Glucagon may be given prior to administration to allow maximum distension of stomach.

Step 2 - Obtain radiographic views

  • Withdraw stomach tube before radiography.
  • See abdominal radiography Radiography: abdomen for details of positioning.
  • Immediately take DV, VD, left and right lateral projections.
  • Repeat after 5-10 min.
  • If abnormality seen make sure it is consistent on several films/views.
  • If barium alone has been used a follow through study of intestines can be performed.
    This is not possible if negative or double contrast study performed.



Step 1 - Assess radiographs

  • Ensure stomach adequately distended for interpretation.
  • Stomach contractions may mimic pathology, including mural thickening and stenosis - if in doubt repeat radiograph.
  • If barium is administered when food is still present in stomach this may mimic pathological filling defects.

Step 2 - Additional radiographic projections

  • Follow up film at 24 hours may be useful for demonstrating retention of barium in stomach, eg foreign body or ulceration.
  • If trying to identify position of stomach take lateral and VD views at 30-40 min when barium is in stomach and small intestine.
  • Double-contrast views give superior mucosal detail, this is the best procedure to identify a gastric ulcer but views are often difficult to interpret.



Potential complications

  • Aspiration of barium either during administration or after procedure if patient vomits.


Reasons for Treatment Failure

  • Inadequate patient preparation, ie stomach not empty.
  • May not identify mucosal lesions or motility disorders.
  • Poor gastric distension.
  • Failure to obtain sufficient radiographs - lesion must be consistent on several films for diagnosis to be made.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Miyabayashi T & Morgan J P (1991) Upper gastrointestinal examinations - a radiographic study of clinically normal beagle puppies. JSAP 32 (2), 83-88 VetMedResource.
  • Evans S M (1983) Double versus single contrast gastrography in the dog and cat. Vet Radiol 24 (1), 6-10 VetMedResource.
  • Evans S M & Laufer I (1981) Double contrast gastrography in the normal dog. Vet Radiol 22 (1), 2-9 Wiley Online Library.

Other sources of information

  • Hall J A & Watrous B J (2000) The effect of pharmaceuticals on radiographic appearance of selected examinations of the abdomen and thorax. Vet Clin North Am S A Pract 30 (2), 349-377, vii PubMed.
  • Brawner W R Jr. & Bartels J E (1983) Contrast radiography of the digestive tract. Indications, techniques, and complications.​ Vet Clin North Am S A Pract 13 (3), 599-626 PubMed.


  • American College of Veterinary Radiology, Executive Director: Dr M Bernstein, PO Box 87, Glencoe, IL 60022, USA.