Feline esophagitis

Inflammation of the feline esophagus is an underdiagnosed condition, yet it can have potentially severe consequences; Toshihiro Watari discusses the predisposing factors, the clinical signs, the imaging modalities required for diagnosis, and the options available to both treat the disease and minimize its recurrence.

Introduction

Although feline esophagitis is not an uncommon condition, it is often missed because of its typically non-specific or subclinical presentation. Mild esophagitis is usually self-limiting, but an esophageal stricture may develop secondary to severe esophagitis, resulting in obstruction of the passage of food. Once formed, strictures require treatment by endoscopic balloon dilation or other invasive methods, and it is, therefore, best to treat esophagitis in the early phases wherever possible. Knowledge of the underlying anatomical features and the risk factors that predispose a cat to esophagitis is essential to better managing this underdiagnosed condition.

Anatomy of the esophagus

The esophagus is the hollow tube that transports food from the pharynx to the stomach. It runs alongside the trachea from the pharynx to the thoracic inlet and then traverses the mediastinum before passing through the diaphragm to enter the stomach. The esophagus has four physiologically normal constrictions; at its origin in the pharynx, at the thoracic inlet, at the level of tracheal bifurcation, and at the esophageal hiatus where it passes through the diaphragm.

The esophageal wall consists of the innermost mucosal epithelia, the lamina propria, the muscularis mucosa, the submucosa, and the two outermost layers of muscle fibers. In dogs, the muscular coat is composed of striated muscle throughout the entire length of the esophagus. In cats, the esophagus has both striated and smooth muscle; the proximal two-thirds are composed of striated muscle, while the distal third is composed of smooth muscle. Consequently, the distal portion of the feline esophagus (caudal to the base of the heart) has circular mucosal folds (Figure 1a) (Figure 1b), which can be seen to form a characteristic “herringbone” pattern on contrast radiography. This difference in musculature explains why dogs with megaesophagus typically fail to respond to prokinetic drugs, while these agents may be successful in inducing distal esophageal motility in cats with the same disorder.