Certain tests must be performed to make a definitive diagnosis of esophagitis and to exclude other disease processes that may cause similar symptoms. A thorough work-up begins with a broad, general baseline of diagnostics, to ensure that one does not overlook other illnesses or factors. In many cases, specific, more advanced tests are performed as well. A complete evaluation should be performed in these animals since an accurate diagnosis is important for treatment and prognosis. Tests may include:

A complete history and a thorough physical examination

A complete blood count (CBC) is most often within normal limits; however, with severe inflammation or secondary pneumonia, one might expect to see elevations in the white blood cell count.

A biochemical profile to rule out other systemic disorders (liver, kidney disease) that may predispose to reflux and, in turn, esophagitis.

A urinalysis

Chest X-rays, although most often within normal limits, are needed to evaluate the size and shape of the esophagus, determine if there is a foreign body present, and to evaluate for the possibility of secondary aspiration pneumonia.

An esophagram (barium swallow) may be necessary if the above tests are inconclusive. It is a very useful test in evaluating the esophageal mucosal (lining) surface, assessing for strictures (narrowing) or dilations. This is usually a very safe test and, in some cases, can be performed in the primary care veterinarian's hospital.

Dynamic contrast fluoroscopy, a type of radiographic evaluation, helps assess esophageal function and detects hypomotility (decreased movement), if present. This test is generally performed at a specialty hospital, and is considered a very helpful tool in the diagnosis of certain esophageal diseases. If a diagnosis is made prior to this step, it is not necessary to perform.

Esophagoscopy evaluates the inside of the esophagus and is usually the most reliable means of diagnosing esophagitis. The mucosa (lining) may appear red, ulcerated, or may even be bleeding. If in doubt, biopsies should be obtained, as they can confirm the diagnosis when viewed under the microscope. One must be cautious, as general anesthesia is necessary, and this can worsen reflux of gastric acid in some cases. It is important to make sure that the individual is otherwise healthy, so as not to create additional risk to the patient. Most often, a specialist is needed to perform this diagnostic procedure, as is special delicate instrumentation.