34th Annual Scientific Meeting proceedings

Dysphagia, ptyalism, vomiting and regurgitation are common clinical signs in brachycephalic breeds. Prevalence of gastrointestinal disease in brachycephalic dog populations, especially in the French bulldog, has been reported to be as high as 97%.¹ The negative intrathoracic pressures generated by increased inspiratory effort is believed to be a major cause of the gastro-oesophageal reflux disease (GERD). Laxity of the phreno-oesophageal ligament and the presence of a sliding hiatal hernia (HH) are also recognised in the many brachycephalic breeds.² The necessity of making a definitive diagnosis of a sliding HH is controversial; in part because the dynamic nature of the condition means that often it is not an easy diagnosis to make. Most commonly, regardless of the diagnosis of a sliding HH, the gastrointestinal signs are managed medically (for example, with the administration of a proton-pump inhibitor, a gastric protectant, omeprazole, and the use of an appropriate feeding regime) and, surgically, with the improvement of airway function.

The presence of concurrent sliding HH is dog’s suffering from BAOS has been described previously.^1-3 Hardie and others’ (1998) performed a case-control study of bulldogs by searching their veterinary medical database at Purdue University for bulldogs presenting with the condition “hiatal hernia”.⁴ For each of the 23 bulldogs found presenting with HH, four control bulldogs were selected, resulting in a total of 115 dogs. Their findings showed that bulldogs with HH were more likely to have at least one diagnosis associated with brachycephalic syndrome than were bulldogs without HH. They concluded that HH was associated with the more severe manifestations of brachycephalic syndrome.

Assessing the true incidence of HH in brachycephalic dogs is less than straightforward. The incidence of clinical signs consistent with a HH (ptyalism, regurgitation/vomiting - especially of frothy material, unexplained periods of dullness, lethargy and anorexia, etc.) in brachycephalic dogs is high. Personal observations in approximately 100 cases would indicate that at least 70% of bulldogs have a clinical history consistent with a HH. This high prevalence of gastrointestinal clinical signs is supported by the findings of Poncet and others (2005).⁵ Their retrospective study of 73 brachycephalic dogs with upper respiratory disease showed that 74% of the dogs presented for respiratory problems had weekly, daily or more frequent episodes of ptyalism, regurgitation and/or vomiting. Interestingly, they only confirmed a diagnosis of axial HH in 3/73 dogs (4.1%) although oesophageal deviation was found in 12/73 dogs (16.4%) and gastro-oesophageal reflux in 23/73 of dogs (31.5%).

Unless the axial HH is trapped in the thoracic cavity, making a definitive diagnosis of axial/sliding HH requires observation of the movement of the lower oesophageal sphincter and local gastric fundus into the caudal thoracic cavity (usually assessed by performing a contrast feeding study with fluoroscopy). Unfortunately, in many instances (lack of fluoroscopic facilities, uncooperative patient, etc.) such studies fail to diagnose the condition. Type I sliding HHs can also be diagnosed using gastro-oesophageal endoscopy (assessment of the gastro-oesophageal junction using retroflexed gastroscopy).⁶ In addition, attempts have been made to measure manometric pressure changes across the gastro-oesophageal junction (GOJ). Features of manometry include; (1) that intragastric pressure is greater than intra-oesophageal pressure, especially during inspiration, (2) that the high-pressure zone of the GOJ has both tonic (lower oesophageal sphincter) and phasic (crural diaphragm) components, and (3) that respiration causes both intraluminal pressure changes and relative movement between pressure sensors and structural components of the GOJ.⁷ Clinically, manometric pressure measurement is less than straightforward and suffers from issues of reliability and inconsistency.

In many instances, the clinical signs of ptyalism, regurgitation and vomiting are significantly reduced following the surgical management of the BOAS. A further improvement of clinical signs can be achieved by the provision of medical management for reflux oesophagitis and HH (gastric protectants, antacids, prokinetics agents, altered feeding regimes, etc.). Personal observations suggest that significant clinical signs consistent with a HH are observed in up to 20-30% of bulldogs following surgical for BOAS. In these individuals, surgical intervention will almost invariably confirm the presence of a sliding HH requiring surgical repair.

Surgical treatment of HH is a focus of controversy in both the human and veterinary literature. Surgical techniques vary depending on the type of hernia present. Surgical techniques that have been performed include hiatal closure, gastropexy, oesophagopexy, anti-reflux procedures, feeding tubes and combinations of the above.⁸ Regardless, hiatal closure is an important surgical component in all surgical HH cases. A left-sided gastropexy is commonly used (in combination with hiatal plication and oesophagopexy) as part of the surgical management of HH in dogs.⁸ The purpose of the gastropexy is considered to help maintain reduction of the stomach. It has also been proposed that a left-sided gastropexy might lead to increase barrier pressure at the GOJ in the postoperative period, and that this might be clinically relevant in the resolution of GERD following HH surgery in the dog.⁹ In humans, an anterior gastropexy is reported as a part of surgical intervention for type II, III and IV HH to prevent gastric volvulus and as an alternative to fundoplication and crural repair.¹⁰ In the dog, any surgical technique producing a permanent gastropexy may be used, but a tube gastropexy has the advantages of allowing enteral feeding while resting the oesophagus, and postoperative decompression of the stomach, if required.⁸ Oesophagopexy has become a routine component of HH repair in dogs and it is invariably combined with hiatal closure and gastropexy. It remains unclear and potentially controversial as to whether an oesophagopexy is required in addition to a gastropexy.⁸

Anti-reflux procedures have been used in animals, the most common of which is the Nissen fundoplication technique.^8,11-14 Since clinical signs associated with most sliding HH are generally that of a reflux oesophagitis, it would seem reasonable that surgery be directed at decreasing or preventing reflux. Use of anti-reflux procedures in small animals has been widely discontinued due to the unacceptably high risk of complications, including dysphagia, ‘gas bloat’ syndrome and the inability to belch, and re-herniation which may lead to compromise of the stomach wall and death.^{8,11,12,15,16} Another option for the surgical management of GERD in humans (rather than traditional fundoplication procedures) is the use of a small, flexible ring of magnets placed around the lower oesophageal sphincter (LINX^â reflux management system). Currently, there are no reports of the use of this system as an anti-reflux device in small animals.

References
Available on request.