Contributors: Barbara J Watrous
Species: Canine | Classification: Techniques
- Use of positive contrast to outline the esophagus.
- Investigation of:
- Simple and quick to do.
- May not identify functional disorder.
- Some risk associated with procedure, eg contrast aspiration.
- Esophagoscopy Esophagoscopy.
- Fluoroscopy (gives more information about esophageal function).
- Ultrasonography for mediastinal/cervical masses.
- 5 min.
- 15 min.
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?
- If esophageal perforation suspected barium is contraindicated.
Water soluble contrast is usually hyperosmolar and if it enters thoracic cavity or lungs can result in pleural or pulmonary effusion so may be more hazardous than a small amount of barium leakage.
- Risk of barium aspiration if pharyngeal dysfunction or regurgitation.
If can make diagnosis on plain radiograph do not do esophagram.
- X-ray machine.
- Processing facilities.
- Protective clothing (lead apron) for radiographer.
- Positioning aids (sandbags, cradle and ties).
- Method of labelling film.
- 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.
- Radiographic film.
- Contrast agent.
- No special requirements for fasting patient.
- Ideally performed in unsedated patient as general anesthesia and sedation can produce transient megaesophagus or mimic strictures due to bolus retention.
- If necessary use low dose acepromazine Acepromazine maleate 0.05-0.1 mg/kg.
Step 1 - Control films
- Lateral thoracic Radiography: thorax and cervical radiographs:
- Check exposure settings and processing.
- Confirm positioning adequate.
- Confirm diagnosis not apparent without contrast study.
Step 2 - Selection of contrast agent
- Water-soluble iodine-based contrast agentif esophageal perforation a possibility.
Still some risk as hypertonic iodine based contrast agents may → pulmonary edema if aspirated.
- Barium or barium/foodmixed are best for demonstrating esophageal strictures or diverticulae.
- Barium pastebest for mucosal lesions.
- Barium liquidmay pass around a partial obstruction and produce false normal radiograph; but may be useful in highlighting foreign body.
Step 1 - Administer contrast agent
- If assessing mucosal detail apply 5-20 ml barium paste to back of tongue.
- May take several minutes to coat esophagus.
- If suspect esophageal diverticulum or stricture adminster contrast by syringe into buccal pouch taking care to avoid aspiration, by using minimal sedation and keeping the dogs head and neck flexed.
- Dose 10-30 ml (liquid barium 70-100% w/v).
- Alternatively mix barium with palatable food and persuade animal to eat.
Step 2 - Obtain radiographic views
- Take lateral and DV/VD cervical and thoracic Radiography: thorax projections, encompassing cranial and caudal and esophegeal sphincters.
Step 1 - Assess radiographs
- For technical quality and to ensure lesion (if present) adequately shown.
- The esophagram may be exposed as a bolus of contrast material is passing through esophagus.
If there is any doubt about the presence of a stricture or diverticulum repeat radiograph to see if bolus has moved on.
Step 2 - Additional radiographic projections
- If suspect partial obstruction on films produced using liquid barium it may be necessary to repeat study with barium and meat.
- Aspiration of iodine-based contrast resulting in pulmonary edema.
- Leakage of iodine-based contrast from esophageal perforation may result in pleural effusion.
- Aspiration of barium may → aspiration pneumonia but usually only coats trachea and removed by action of cilia and coughing.
- Even with aspiration of a large amount of barium suphate, cough reflux will clear that in the airways. Alveolarized barium sulphate will be phagocytized by macrophages. The inert character of this contrast medium provides good long-term prognosis.
Reasons for Treatment Failure
- Motility disorder may not be diagnosed.
- Barium liquid bypasses partial obstruction.
- Unable to get animal to eat barium and food mix.
- Recent references from PubMed and VetMedResource.
- Tamm I & Kortsik C (1999) Severe barium sulfate aspiration into the lung - Clinical presentation, prognosis and therapy. Respiration 66 (1), 81-84 PubMed.
- Kleine L J (1974) Radiologic examination of the esophagus in dogs and cats. Vet Clin North Am 4 (4), 663-686 PubMed.
Other sources of information
- Thrall D E (1998)Textbook of Veterinary Diagnostic Radiology.pp 269-284.
- American College of Veterinary Radiology, Executive Director, Dr M Berstein, P O Box 87, Glencoe, IL 60022, USA. www.acvr.ucdavis.edu