33rd Annual Scientific Meeting proceedings

Gastrointestinal disease has been recognised in brachycephalic breeds for some time (1); it is prevalent and appears to be related mainly to poor oesophageal function (2).  The clinical signs of this may be similar to those of brachycephalic obstructive airway syndrome (BOAS), as laboured breathing, stridor and tachypnoea were clinical signs described in non-brachycephalic dogs with hiatal hernia by Luciani and others (3). Furthermore, oesophageal disease may also compound pure BOAS by leading to aspiration pneumonia, but also with other effects of regurgitation that are hard to characterise, such as rhinitis (5) and surface tension effects of refluxed fluid in the narrow upper airway. Hiatal hernia (HH) is only one part of an array of abnormalities present in these breeds, others being oesophageal redundancy, ineffective secondary peristaltic waves, prolonged oesophageal transit time and gastro-oesophageal reflux (4).

Diagnosis is based on:

1. History – regurgitation is classically a passive process, although anecdotally these dogs often have some features of vomiting. They will regurgitate froth and food, sometimes at exercise, sometimes at rest; in severe cases, this may be multiple times per day. They may show signs of ‘clinically silent’ regurgitation, such as excessive licking of the air, their own feet or floors/furniture. They may exhibit signs of nasopharyngeal disease such as nasal obstruction, nasal discharge and ‘reverse sneezing’ (5).  Cases with HH will typically have more severe signs compared to patients with just slow oesophageal transit times or gastro-oesophageal reflux and may respond less well to medical management.
2. Imaging – contrast radiography and CT may give false negatives as HH may not be continuously present, so contrast swallow studies using video fluoroscopy are more helpful. Restraint is easier, as the animals can stand and no anaesthesia is required. Some patients will refuse to eat, however.
3. Endoscopy – this is very useful in experienced hands but requires general anaesthesia and so may be best reserved if the patient does not cooperate with videofluoroscopy or the if clinician feels the videofluoroscopy has failed to demonstrate a HH when there is a high index of suspicion. Temporary occlusion of the endotracheal tube during endoscopy may increase the likelihood of diagnosing a sliding hiatal hernia (6)

Is diagnosis necessary?
In most cases, diagnosis of HH is not necessary. This is because HH is only one component of multiple causes of reflux in these breeds; it is an oversimplification to think that it is the most important. The clinician should, however, have an awareness that oesophageal disease plays a role in BOAS, both in causing ongoing clinical signs despite treatment for BOAS, but also in morbidity in the peri- and post-operative period.

Treating regurgitation with routine BOAS surgery has a role but is unlikely to be a complete solution: Appelgrein and others (7) did not find the amount of reflux as measured by oesophageal pH probes was related to the severity of respiratory signs or whether previous surgery was performed, and although owners believed regurgitation improved after surgery, Mayhew and others (8) found there was no significant  improvement in oesophageal function score on video fluoroscopy after BOAS surgery.

Non-specific management of oesophageal disease in the  pre- and post-operative periods should be considered initially and can be useful long term: softened commercially-available hypoallergenic diet with no human foods and treats. Postural feeding and slow feeding may also be beneficial. Medical treatment for oesophagitis with proton-pump inhibitors such as omeprazole can be used in the peri-operative period but are likely to be much less effective than careful dietary management. Anti-emetic medication can be useful in the peri-operative period due to the unusual mixture of regurgitation with vomiting seen in the brachycephalic, and especially as stress will often worsen clinical signs.

Investigations for HH with swallow studies +/- endoscopy are worth undertaking if HH surgery is being considered i.e. if an animal is failing to respond to management, and/or has severe signs of reflux. The clinical signs of HH can often be well controlled, however, with these conservative management techniques and so a specific diagnosis is not essential if surgical management is not required.

References

1. Poncet CM, Dupre GP and others (2005): Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. JSAP 46, 273 – 279
2. Reeve EJ, Sutton D and others (2017): Documenting the prevalence of hiatal hernia and oesophageal abnormalities in brachycephalic dogs using fluoroscopy. JSAP 58, 703 - 708
3. Luciani E, Reinero C and Grobman (2022): Evaluation of aerodigestive disease of sliding hiatal hernia in brachycephalic and nonbrachycephalic dogs. J Vet Intern Med 36(4): 1229 – 1236
4. Elvers C, Chicon Rueda R and others (2019): Retrospective analysis of esophageal imaging features in brachycephalic versus non-brachycephalic dogs based on videofluoroscopic findings. J Vet Intern Med 33(4): 1740 – 1746
5. Grobman M (2021): Aerodigestive Disease in Dogs. Vet Clinics of N America: Small Animal Practice 51 (1), 17 - 32
6. Broux O, Clercx C and others (2018): Effects of manipulations to detect sliding hiatal hernia in dogs with brachycephalic airway obstructive syndrome. Vet Surg 47, 243 - 251
7. Appelgrein C, Hosgood G and others (2022): Quantification of gastrooesopheageal regurgitation in brachycephalic dogs. J Vet Intern Med 36(3): 927 – 934
8. Mayhew PD, Marks SL and others (2023): Effect of conventional multilevel brachycephalic obstructive airway syndrome surgery on clinical and videofluoroscopic evidence of hiatal herniation and gastroesophgeal reflux in dogs. Vet Surg 52: 238 - 248